JP2003075107A - Conductive fiber bundle-included plastic composite material, strain-stress detection device and strain-stress detection method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem that development of technology having higher detection sensitivity, capable of detecting even the direction of a strain or a stress is required, as a sensor for detecting the strain or the stress caused in a structure or a member. SOLUTION: This conductive fiber bundle-included plastic composite material 10 is constituted by burying integrally conductive fiber bundles 11 extending along the longitudinal direction of a plastic material 12 on positions shifted to the outside by avoiding the sectional center part of the long cylindrical plastic material 12. In this strain-stress detection device, an electric resistance is measured by connecting a resistance measuring device to a sensing circuit formed by connecting each conductive fiber bundle 11 between the plastic composite materials 10. In this strain-stress detection method, the directivity of the strain or the stress is grasped by comparing electric resistances of the plural conductive fiber bundles 11 installed in the plastic composite material 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention functions as a sensor for detecting the action of strain or stress as a change in the electrical resistance value of a conductive fiber bundle, and also as a heating element by energizing the conductive fiber bundle. The present invention relates to a conductive fiber bundle-containing plastic composite material, a strain / stress detection device, and a strain / stress detection method, and in particular, a conductive fiber bundle-containing plastic composite material which is formed in a rod shape and is excellent in detecting strain / stress in a bending direction, and The present invention relates to a strain / stress detection device and a strain / stress detection method.

[0002]

2. Description of the Related Art Conventionally, for example, a method using a resistance line strain gauge is known as a means for knowing the stress generated inside a member. As is well known, a resistance strain gauge is a generally flat plate-shaped one having a resistance wire made of platinum or the like arranged in a meandering shape, and changes in the shape of the resistance wire (length The strain of the object is grasped by the change of the resistance value due to the change and the change of the sectional area, and the stress is calculated from the strain.
However, in the stress detection by this resistance wire strain gauge,
Since the measured strain and the applied load have a linear relationship, even when a large live load is temporarily added, the strain display becomes 0 (zero) in the state where the live load is unloaded, If the timing of the measurement is missed, there is a serious drawback that the fact cannot be recognized despite the fact that excessive stress is actually generated. Moreover, there is a problem that the strain gauge can be provided only on the outer surface of the object, and the strain gauge itself is expensive.

In view of this, Hiroaki Yanagida, who is one of the inventors of the present invention, can use carbon fiber as a means which can be easily provided inside a member and can detect the strain and stress state of a structure with high accuracy. We have proposed a conductive fiber bundle-containing plastic composite material in which a conductive fiber bundle made of, for example, is embedded in a plastic material and integrated, and as an invention relating to this, Japanese Patent Application Laid-Open No. 6-50830 “Plastic fiber bundle-containing plastic” is disclosed. Strain / stress detection method using composite material and conductive fiber bundle-containing plastic composite material used therefor ", JP-A-7-182
No. 571 “Structure destruction alarm device and structure destruction alarm method” has already been proposed. In any of the above-mentioned inventions, the conductive fiber bundle-containing plastic composite material is formed by arranging carbon fiber bundles as conductive fiber bundles in a grid shape, embedding them in the plastic material, and integrating them into a grid shape as a whole. That is, by measuring the electric resistance value of the conductive fiber bundle and detecting the change in the electric resistance value corresponding to the strain of the conductive fiber bundle, the plastic composite material having the conductive fiber bundle is configured. It is possible to know the strain or stress state of the conductive fiber itself or the place where the conductive fiber is attached. Japanese Unexamined Patent Publication No. 6-50830 utilizes that the conductive fiber exhibits a peculiar electric resistance value in relation to strain,
It is possible to notify the limit of proof strength of plastic composite materials by self-diagnosis and to use it for ground damage monitoring. The invention described in Japanese Patent Application Laid-Open No. 7-182571 is adapted to detect breakage of a conductive fiber so that it can be used for detecting an intruder into a building or the like or an artificial breakage of a structure.

[0004]

However, any of the above-mentioned inventions (Japanese Patent Application Laid-Open Nos. 6-50830 and 7-1).
No. 82571), the stress and the breakage acting on the structure can be detected, but the problem that the direction in which the stress is applied cannot be detected remains. For example, in predicting damage to a large structure such as a building, it is necessary to grasp the direction and distribution of strain in the entire structure, and a technique capable of detecting the stress direction is required. Further, in predicting damage to a large structure such as a building as described above, it is necessary to detect a very small strain over a wide range of the structure, and high detection sensitivity is required. However, as shown in FIG. 23, the conventionally provided conductive fiber bundle-containing plastic composite material has a structure in which the conductive fiber bundle 2 is arranged and embedded in the central portion of the cross section of the plastic material 1 and is continuous in a mesh shape. Due to this structure, even if the conductive fiber bundle-containing plastic composite material undergoes bending deformation due to an external force, the conductive fiber bundle does not bend much, and the stress acting especially in the bending direction of the conductive fiber bundle-containing plastic composite material However, there is a problem that the detection sensitivity is low and the applicable range is limited.

Further, in any of the above-mentioned inventions, since the conductive fibers arranged in a lattice shape are embedded and integrated in a plastic material, there is a problem that mass production is difficult and cost reduction is difficult. . Furthermore, as the conductive fiber bundle-containing plastic composite material, one using carbon fiber as the conductive fiber is generally used, and the conductive fiber bundle-containing plastic composite material is heated by applying an additional voltage to the conductive fiber. It may function as a heating element. in this case,
In the conductive fiber bundle-containing plastic composite material in which the conductive fibers are arranged in a grid as described above, when the conductive fibers have a bent portion, the bent portion is locally heated, and the temperature distribution varies. There were challenges. Therefore, when the use as a heating element is taken into consideration, there are restrictions on the arrangement of the conductive fibers. In addition, when the conductive fiber bundle-containing plastic composite material is used as a snow stop fence or the like, there is a problem in that it is easily deformed by long-term installation, and the bending deformation of the conductive fiber easily causes local heating during energization.

The present invention has been made in view of the above-mentioned problems, and it is formed in a rod shape, which can ensure excellent detection sensitivity particularly to strain and stress in the bending direction, and also the direction of the applied stress An object of the present invention is to provide a conductive fiber bundle-containing plastic composite material, a strain / stress detection device, and a strain / stress detection method that can be detected, can be manufactured easily, and can be manufactured at low cost.

[0007]

According to a first aspect of the present invention, one or a plurality of conductive fiber bundles are embedded and integrated in a rod-shaped plastic material in parallel with the longitudinal direction of the plastic material. In addition, the conductive fiber bundles are arranged at positions displaced outward so as to avoid the central portion of the cross section orthogonal to the longitudinal direction of the plastic material, and the conductive material is provided at both longitudinal end portions of the plastic material. A conductive fiber bundle-containing plastic composite material, which is characterized in that an energizing terminal portion of the fiber bundle is provided, is a means for solving the above problems. According to a second aspect of the present invention, in the conductive fiber bundle-containing plastic composite material according to the first aspect, the plastic material is formed in a circular cross section, and the plastic material is formed from the center of the cross section orthogonal to the longitudinal direction toward the outer periphery. It is characterized in that the conductive fiber bundle is arranged at a position ½ of the radius of the cross section or in an area outside thereof. According to a third aspect of the present invention, in the conductive fiber bundle-containing plastic composite material according to the first or second aspect, a plurality of conductive fiber bundles are provided in a circumferential direction of a cross section orthogonal to the longitudinal direction of the plastic material. It is characterized in that it is almost evenly distributed in the locations. The invention according to claim 4 is the conductive fiber bundle-containing plastic composite material according to any one of claims 1 to 3, wherein the conductive fiber bundle is in a circumferential direction of a cross section orthogonal to the longitudinal direction of the plastic material. It is characterized in that it is arranged at four locations that are almost evenly distributed. According to a fifth aspect of the present invention, in the conductive fiber bundle-containing plastic composite material according to any of the first to fourth aspects, a plurality of conductive fiber bundles embedded in the plastic material have a constant cross-sectional shape. It is characterized by The invention according to claim 6 is
The conductive fiber bundle-containing plastic composite material according to any one of claims 1 to 5, wherein the plastic material includes, in addition to the conductive fiber bundle, a reinforcing fiber bundle having a larger elongation than the conductive fiber bundle. It is characterized in that it is embedded so as to extend substantially along the conductive fiber bundle. A strain / stress detection device according to a seventh aspect of the present invention is configured by using a plurality of the conductive fiber bundle-containing plastic composite materials according to any one of the first to sixth aspects, and the conductive fiber bundle-containing plastic composite material. A sensor unit in which conductive fiber bundles are electrically connected to each other so as to be electrically conductive and conductive fiber bundles of a plurality of conductive fiber bundle-containing plastic composite materials are connected in series, and each of both ends of this sensor unit It has a resistance measuring device connected to the energizing terminal portion. The strain / stress detection method according to the invention of claim 8 measures the electrical resistance of a plurality of conductive fiber bundles of the conductive fiber bundle-containing plastic composite material according to claim 3 or 4, and a part of the conductive fibers is measured. When an increase in the resistance value of the conductive fiber bundle is detected, the direction of the strain generated in the conductive fiber bundle-containing plastic composite material is determined from the distribution of the resistance value measured for each conductive fiber bundle. Is characterized by.

According to the present invention, when the rod-shaped conductive fiber bundle-containing plastic composite material is bent and deformed, the increase in the electrical resistance of the conductive fiber bundle can be detected to detect the occurrence of strain sensitively. The conductive fiber bundle is an integration of a large number of continuous conductive fibers, and the electrical resistance measured for the conductive fiber bundle is obtained by breaking some or all of the conductive fibers due to strain in the bending direction. Is observed. In addition, in the conductive fiber bundle-containing plastic composite material having a configuration (claims 3 and 4) in which a plurality of (for example, four) conductive fiber bundles are dispersed and arranged in the circumferential direction of the cross section, the electrical conductivity of each conductive fiber bundle is increased. The direction of strain and stress can also be detected from the distribution of resistance. This conductive fiber bundle-containing plastic composite material, the conductive fiber bundle functions as a reinforcing material for the plastic material,
Sufficient strength can be secured by embedding a separate reinforcing fiber bundle (claim 6). Therefore, the conductive fiber bundle-containing plastic composite material itself can be assembled as a structure or used as a reinforcing material. Further, as the conductive fiber bundle, it is possible to employ, for example, a carbon fiber bundle or the like that generates heat when energized. In this case, the conductive fiber bundle-containing plastic composite material itself can be used as a heating element.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings. 1 (a) and 1 (b) are diagrams showing a conductive fiber bundle-containing plastic composite material (hereinafter sometimes abbreviated as "plastic composite material") according to the present invention, in which (a) is a front view. , (B) is a sectional view taken along line AA of (a).

The plastic composite material 10 has a construction in which a conductive fiber bundle 11 is embedded in a plastic material 12 formed into a straight rod shape having a circular cross section, and the conductive fiber bundle 11 is made of a plastic material 12. Are arranged linearly in the plastic material 12 in parallel with the longitudinal direction thereof (the same as the longitudinal direction of the plastic composite material 10) and embedded and integrated. Further, in this plastic composite material 10, the conductive fiber bundles 11 are provided at four locations in the cross section of the plastic material 12 which is orthogonal to the longitudinal direction and which are substantially evenly distributed in the circumferential direction.
Are arranged one by one (see FIG. 1B). However, the conductive fiber bundle 11 is arranged at a position outside the half of the radius of the cross section of the plastic material 12 from the center of the cross section orthogonal to the longitudinal direction toward the outer periphery (in the region shown in FIG. 1 (b)). ,
1 is a region radially outside of the imaginary line D).
In the example of (b), the conductive fiber bundle 11 is arranged and buried near the outer surface of the plastic material 12 with a slight covering thickness of about 1 mm or less secured to the outside. The cross-sectional diameter of the plastic composite material 10 is formed to be about 8 mm to several tens of mm.

As the conductive fiber bundle 11, a carbon fiber bundle in which a large number of continuous carbon fibers are collected and integrated with a resin is used as the conductive fiber bundle 11. In the plastic composite material 10, the conductive fiber bundles 11 are embedded so as to extend over the entire length of the plastic material 12 in the longitudinal direction, and also serve as the reinforcing fibers of the plastic composite material 10.

The plastic material 12 here is FRP (fiber reinforced plastic) in which a glass fiber bundle is embedded as a reinforced fiber bundle 13 in a plastic as a base material.
Has been adopted. The reinforcing fiber bundle 13 extends almost along the conductive fiber bundle 11 and is embedded and integrated in a plastic substrate. As the material of the reinforcing fiber bundle 13, for example, boron fiber, aramid fiber, or the like can be adopted other than the above-mentioned glass fiber. However, as the reinforcing fiber bundle, one having a larger elongation than the conductive fiber bundle 11 is adopted.

As shown in FIG. 4, current-carrying terminal portions 14 provided at both longitudinal ends of the plastic composite material 10.
Is for electrically connecting the electric circuit outside the plastic composite material 10 and the conductive fiber bundle 11 so as to be electrically conductive. The energizing terminal portion 14 is, for example, the conductive fiber bundle 1 located at the longitudinal end of the plastic composite material 10.
Although various configurations such as 1 tip portion and a pin terminal connected to the tip portion of the conductive fiber bundle 11 can be adopted, here, as shown in FIG. 4, to the end surface 12a of the longitudinal end portion of the plastic material 12. The conductive layer is formed in a film shape or a pad shape by depositing a conductive metal such as solder or adhering and fixing a conductive metal thin plate piece. This energizing terminal portion 14
Are individually formed for each of the plurality of conductive fiber bundles 11 embedded in the plastic material 12, and the current-carrying terminal portions 14 are electrically insulated from each other through the region 16 in which the conductive layer is not formed. There is.

The screw portion 17 formed by processing the outer peripheral portion of the plastic material 12 located at the both ends in the longitudinal direction of the plastic composite material 10 is, for example, as shown in FIGS. The connectors C1 and C2 can be connected by screwing. Not limited to the connector of the electrical connection component 20, if a connector which is similarly connected by screwing to the screw portion 17 is adopted, various electric devices, electric circuits, etc. can be connected to the plastic composite material 10 through this connector. Can be easily connected to the conductive fiber bundle 11. 3A, 3B, and 4 exemplify one end portion of the plastic composite material 10 in the longitudinal direction,
The other end of the plastic composite material 10 has the same structure.

Since the plastic composite material according to the present invention is rod-shaped, it can be easily mass-produced by pultrusion and cost reduction. That is, as shown in FIG. 5, a resin injection machine 31 is connected to a mold 30 for molding a plastic material of a plastic composite material, and the resin injection machine 31 is used to form the mold 3
A required amount of resin (plastic material) is continuously pressed into 0, and the conductive fiber bundle 11 and the reinforcing fiber bundle 13 are sent out (pulled out) from the inlet 32 of the mold 30 toward the outlet 33. As a result, a rod-shaped plastic composite material (bar material 34) containing the conductive fiber bundles 11 and the reinforcing fiber bundles 13 and molded into an intended cross-sectional shape from the outlet 33 of the mold 30.
Is sent out as a pultruded product. In the production of a plastic composite material using this pultrusion molding, rods corresponding to one length of the plastic composite material may be formed by pultrusion molding one by one. By cutting out the plastic composite material having the length of, it is possible to further improve the manufacturing efficiency of the plastic composite material and reduce the cost. Then, a pultruded product (bar material) having a length of one is threaded at both ends (screw portion 1
7) and the formation of the energizing terminal portion, and the like, so that the intended plastic composite material can be formed. In addition, if it is a rod-shaped plastic composite material, continuous manufacturing can be easily realized even by extrusion molding, and manufacturing efficiency can be improved and cost can be reduced.

6 (a) and 6 (b) to FIG. 8 show a plurality of plastic composite materials 10 along a long structure 40 (here, a fence, which may be referred to as a "fence 40" hereinafter). The conductive fiber bundles 1 of a plurality of plastic composite materials 10 are arranged and mounted, and the conductive fiber bundles 11 are electrically connected to each other between the adjacent plastic composite materials 10.
1 constitutes a sensor unit 41 connected in series, and a resistance measuring device 60 is connected to the conductive fiber bundle 11 at both ends of the sensor unit 41 to detect strain or stress generated in the fence 40. -The example which assembled the stress detection apparatus 42 is shown. 9 and 10 show that a large number of plastic composite materials 10 are connected to each other to assemble a sensor unit 50 in a grid shape and the plastic composite materials 10 adjacent to each other are assembled.
The conductive fiber bundles 11 are electrically connected to each other between the conductive fiber bundles 11 to form a sensor unit 50 in which the conductive fiber bundles 11 of the plurality of plastic composite materials 10 are connected in series. An example in which a resistance measuring instrument 60 is connected to both ends of a circuit in which the conductive fiber bundles 11 of the book are connected in series, and a strain / stress detection device 51 for detecting strain or stress generated in the sensor unit 50 is assembled. Show. Also,
11 shows a wall 52 as an example of a structure constructed by placing concrete using the sensor unit 50 of the strain / stress detection device 51 as a framework, and FIG. 12 shows the sensor unit 50 itself of the strain / stress detection device 51. It is a figure which shows the state erected on the slope of the ground T as a fence-shaped sensor body which doubled as an earth retaining fence or a snow retaining fence.

The strain / stress detecting devices 42 and 51 are arranged so that the strain and stress generated in the structure in which the sensor units 41 and 50 are installed by observing an increase in the resistance value measured by the resistance measuring device 60, Sensor unit 41, 5
The strain and stress generated at 0 can be detected. That is, distortion
The stress detecting devices 42 and 51 are configured to measure the resistance value of the conductive fiber bundle 11 (here, carbon fiber bundle) of the plastic composite material 10 constantly or periodically by the resistance measuring device 60. The bending direction is given to the conductive fiber bundle 11 in the plastic composite material 10 due to the bending direction distortion (bending strain) generated in the plastic composite material 10 constituting the sensor unit, and the conductive fiber bundle 11 is formed. When a part or all of the conductive fibers (here, carbon fibers) that operate are broken, an increase in resistance value is observed, and generation of strain or stress is detected.

For example, in the strain / stress detection device 42 illustrated in FIGS. 6 to 8, each plastic composite material 10 constituting the sensor unit 41 is extended at the upper end of the fence 40 in the extending direction of the fence 40 (left-right direction. 7 left and right) is arranged on the lower surface side of the upper frame member 43 that is continuously arranged,
It is fixed integrally with the upper frame member 43. In addition, all the plastic composite materials 10 constituting the sensor unit 41
Are installed on the fence 40 in such a manner that the four built-in conductive fiber bundles 11 are arranged at four positions in the vertical and horizontal directions (see FIG. 6).
(See (a) and (b)), adjacent plastic composite materials 1
The conductive fiber bundles 11 are connected to each other between 0, which are arranged at the same position in the plastic composite material 10, that is,
Lower conductive fiber bundle 11 (reference numeral 111 in FIG. 6A)
And the upper conductive fiber bundle 11 (reference numeral 1 in FIG. 6A)
12) each other, the conductive fiber bundle 11 on the left side (in FIG. 6 (a),
Reference numeral 113), the conductive fiber bundle 11 on the right side (see FIG. 6).
In (a), reference numeral 114) are connected to each other. As a result, as shown in the schematic diagram of FIG.
In 1, the number of sensing circuits 71 to 74 (electrical circuits) formed by connecting the conductive fiber bundles 11 at the same position of the plurality of plastic composite materials 10 (either up, down, left or right of the cross section of the plastic composite material 10) is four. The books are formed in parallel. The sensing circuit 71 is one in which the lower conductive fiber bundles 111 are connected, the sensing circuit 72 is one in which the upper conductive fiber bundles 112 are connected, and the sensing circuit 73.
Is a connection between the conductive fiber bundles 113 on the left side, and the sensing circuit 74 is a connection between the conductive fiber bundles 114 on the right side.

Both ends of each of the sensing circuits 71 to 74 are connected to the resistance measuring device 60 via a connection circuit 61 (see FIG. 7) composed of an electric wire or the like.
Measures the electrical resistance. However, although the connection circuit 61 is shown by a single line in FIG. 7, each connection circuit 6
Reference numeral 1 denotes, for example, one or a plurality of electric wires to secure the same number of cores as the number of sensing circuits, and each sensing circuit 71 to 74 is individually connected to the resistance measuring device 60 (FIG. 13). reference). For connecting the conductive fiber bundles 11 between the adjacent plastic composite materials 10, for example, the electrical connection component 20 illustrated in FIGS. 2 to 4 is used, and the conductive fibers of the adjacent plastic composite materials 10 are connected. The bundles 11 are properly connected so that they are on the lower side, on the upper side, on the left side, and on the right side. The specific configuration of the electrical connection component 20 will be described later in detail.

For example, as shown in FIG. 8, when the fallen tree 44 locally deforms the upper frame member 43 to bend downward, the plastic composite material 10 installed at this deformed position also changes to the upper frame member 43. Receives deformation (bending strain) as a unit.
When some or all of the conductive fibers (here, carbon fibers) forming the conductive fiber bundle 11 are broken due to the deformation of the plastic composite material 10, the measured value of the electric resistance measured by the resistance measuring device 60 Since the increase is observed, it is detected that the structure 40 is deformed (strained).
When the resistance measuring device 60 detects an increase in the resistance value, it outputs an abnormality detection signal by a radio signal, an electric signal, or the like to the management office 62.
To output and transmit. In the management office 62, this abnormality detection signal can be utilized for repairing the deformed portion. However,
The resistance measuring device 60 monitors the increase of the resistance value in units of the sensing circuits 71 to 74, and measures the measured value in any one of the plurality of sensing circuits 71 to 74 connected to the resistance measuring device 60. An abnormality detection signal is output when an increase in (resistance value) is detected. The abnormality detection signal is information for identifying the sensing circuits 71 to 74,
In addition, whether the measured value (resistance value) of each of the sensing circuits 71 to 74 is included, or the signal corresponding to the information or the measured value is transmitted to the management office 62 itself is the abnormality detection signal.

By the way, when a bending strain (deformation of bending or bending) is applied to the plastic composite material 10, the outer peripheral side of the bending or bending of the plastic composite material 10 is the pulling side, and the inner peripheral side of the bending or bending is the compression side, The conductive fiber bundle 11 arranged on the outer peripheral side of the deformation has a tensile force,
A compressive force acts on the conductive fiber bundle 11 arranged on the inner peripheral side of the deformation. Therefore, like the plastic composite material 10, in the case of a rod-shaped plastic composite material having a configuration in which a plurality of conductive fiber bundles are dispersed and embedded in a plurality of locations along the circumferential direction of the cross section when bending strain is applied. The strain applied to each conductive fiber bundle is not uniform. Also in the above-described strain / stress detection device 42, when the downward load locally acts on a part of the plastic composite material 10 in the longitudinal direction by the above-described fallen tree 44 or the like to cause bending strain, four conductive materials are used. The strain applied to the natural fiber bundle 11 is not uniform, and
In, the conductive fiber bundle 11 arranged on the lower side is likely to be stretched and distorted by the tensile force, and the conductive fiber bundle 11 arranged on the upper side is likely to buckle due to the compressive force.

The present inventors conducted a bending test on the test piece of the plastic composite material 10 and the test piece of the comparative example, and compared the detection sensitivity of strain and stress. In this bending test, as shown in FIG. 14A, a rod-shaped test piece 80 was
The test piece 80 is placed on a pair of lower indenters 81 and 82 arranged so as to secure the span L, and an intermediate position between the supporting positions of the lower indenters 81 and 82 of the test piece 80 is moved downward by the upper indenter 83 moved at a constant speed. Pressing to give bending strain to the test piece 80 3
It is point bending, the bending strain of the test piece 80, and the test piece 8
The electrical resistance of the conductive fiber bundle embedded in 0 was measured. The results are shown in FIGS. The resistance value of the conductive fiber bundle is measured by the resistance measuring device 60 connected to the conductive fiber bundle embedded in the test piece 80, and the test piece 8
The bending strain of 0 is the strain gauge 8 attached to the test piece 80.
It is a calculated value calculated based on the measurement data of 4. The strain gauge 84 is attached to the lower surface side of the test piece 80 so as to face the pressing position of the test piece 80 by the upper indenter 83, and the elongation strain of the test piece 80 at this position is accurately measured.

First, a test piece 80 having a sectional structure shown in FIG. 14B (comparative example. In FIG. 14B for distinguishing the test piece,
14C, and a test piece 80 having a cross-sectional structure shown in FIG. 14C (example: plastic composite material 10 according to the present invention. Reference numeral 80b in FIG. 14C for distinguishing the test piece)
The comparison of the test results of the bending test performed for The test conditions are shown below.

(Example) Test piece 80b: the plastic composite material 1 according to the present invention
0 is molded into a rod shape with a circular cross section having a diameter of 10 mm. The four conductive fiber bundles 11 embedded and integrated in the plastic material 12 are each formed by integrating a large number of continuous carbon filaments with a resin to form a circular rod shape with a diameter of 1 mm. . In addition, the four conductive fiber bundles 11 are evenly arranged at four positions in the circumferential direction of the cross section of the plastic composite material 10 having a circular cross section, and each conductive material embedded and arranged near the outer surface of the plastic composite material 10. The covering thickness and the like of the plastic material 12 that covers the outside of the fiber bundle 11 is as shown in FIG.
This is as described above with reference to (b) and the like.

(Comparative Example) Test piece 80a: A cross section structure in which only one conductive fiber bundle 11 is embedded in the center of the cross section of a plastic material 12 having a circular cross section with a diameter of 10 mm. The material of the plastic material 12 and the configuration of the conductive fiber bundle 11 are the same as those of the test piece 80b of the example.

Test: As shown in FIG. 14 (a), a test piece 80 is provided between the three indenters 81 to 83 forming the test jig.
Was placed and a three-point bending test was performed. The moving speed of the upper indenter 83 is 1.0 mm / min. The test jig is JIS
It has a configuration based on the bending test of K-7055,
The indenters 81 to 83 have a circular rod shape with a diameter of 5 mm, and the span L between the lower indenters 81 and 82 is 100 mm. The test result of the test piece 80a of the comparative example is shown in FIG. 15, and the test result of the test piece 80b of the example is shown in FIG.

However, FIG. 16 (also common to FIGS. 17 to 19)
Then, as shown in FIG. 14C, the test piece 80b is set on the test jig in a direction in which the four conductive fiber bundles 11 are arranged vertically and horizontally. ΔR-bo in FIGS.
tm, ΔR-top, ΔR-front, ΔR-b
ack shows the measurement results of the resistance increase rate (described later) of the four conductive fiber bundles 11 of the test piece 80b, and ΔR-bottom is the conductivity arranged on the lower side in FIG. 14 (c). Fiber bundle 11 (reference numeral 11b in FIG. 14 (c)),
ΔR-top is the conductive fiber bundle 11 (reference numeral 11t in FIG. 14C) arranged on the upper side of FIG. 14C, ΔR-fo.
14 (c) is a conductive fiber bundle 11 having a reference numeral “11cf”, and ΔR-back is a reference numeral “11” in FIG. 14 (c).
It corresponds to the conductive fiber bundle 11 of "cb".

In FIGS. 15 to 19, the bending stress (MPa) on the vertical axis is the bending stress (calculated value) acting on the test piece 80. The resistance increase rate ΔR (%) is the increase rate of the resistance value of the conductive fiber bundle 11 measured by the resistance measuring device 60, and is the measured value (resistance value R
₀ ) and the measured value (R) in which the bending load was increased by the action.
From the increase (R−R ₀ ), the resistance increase rate ΔR (%) = (R−R ₀ ) / R ₀ is calculated.

As shown in FIG. 15, a test piece 80 of a comparative example.
In the case of a, the bending strain started to break at 2.4%. The electric resistance of the conductive fiber bundle 11 starts to increase from around 3.2% in bending strain, and greatly increases to around 5% at which breakage of the test piece 80a has progressed considerably.

As shown in FIG. 16, the test piece 80b which is the plastic composite material 10 according to the present invention exhibits the maximum strength when the bending strain is around 2.8%. In addition, when the bending strain is around 1.7%, especially ΔR-bottom and ΔR-
There is a sharp rise in top. Although not shown in the drawing, as a result of performing the test on the plurality of test pieces 80b under the same condition, ΔR-front and ΔR-back are the test pieces 8
The bending strain of 0b may or may not increase in the vicinity of 1.8%, and there is variation. The increase in ΔR-bottom is due to the progress of breakage of the conductive fibers (here, carbon fibers) of the conductive fiber bundle 11b due to the elongation strain on the tensile side of the test piece 80b, and the increase in ΔR-top is the test. Conductive fiber bundle 11t due to buckling of the piece 80b on the compression side
This is due to the progress of breakage of the conductive fibers (here, carbon fibers), and ΔR-bottom and ΔR-top
Simultaneous rise of No. indicates that the deformation of the test piece 80b on the tensile side and the compression side proceed at the same time. When the bending strain of the test piece 80b exceeds 1.7% and is 5.0 to 5.4%, the test piece 8b
Until the entire 0b bends (bends), ΔR-botto
Only m continues to rise as the bending strain increases, but for other ΔR-top, ΔR-front, and ΔR-back, until just before the entire test piece 80b bends,
No clear upward trend is observed.

Next, the test piece 80b of the example was subjected to a bending test by changing the sectional radius r of the indenters 81 to 83 and the span L between the lower indenters 81 and 82. The result is shown in FIG.
It shows in FIG. In FIGS. 17 to 19, the lower indenters 81 and 82 are shown.
A span L = 120 mm is secured between them. 17 to 19, the cross-sectional radius r of the indenters 81 to 83 used is different, 5 mm in FIG. 16, 10 mm in FIG. 18, and 20 in FIG.
mm. Span L between lower indenters 81 and 82, indenter 81
Test conditions other than adjusting the cross-sectional radius r of ~ 83 are:
It is similar to FIG.

From the results of FIGS. 16 to 19, as a tendency,
The increase in resistance value (resistance increase rate) due to the increase in bending strain is Δ
R-bottom is the largest, followed by ΔR-top, and ΔR-front and ΔR-bac
At k, the fracture of the test piece 80b progresses and the buckling of the entire test piece 80b starts (where the rate of increase in resistance of all the conductive fiber bundles 11 becomes very large due to a rapid increase to infinity. 4.0% strain or more), the relationship of increase in resistance increase rate with increase in bending strain does not appear clearly. In addition, in FIGS. 16 to 18, bending strains 1.6 to 1.
At 8%, a sharp rise in ΔR-bottom and ΔR-top (the corresponding simultaneous rising portions are denoted by reference numeral 85. Hereinafter referred to as “initial rise”) is seen, but in FIG. 19, the ΔR-bottom is in this bending strain region. A sharp rise (in Fig. 19,
The portion showing this rapid increase is denoted by reference numeral 85a), and a clear increase tendency of ΔR-top is not recognized until the bending strain reaches around 3.0%.

When the initial rise 85 was confirmed in FIGS. 16 to 18, the test was stopped and the test piece 80b was confirmed. As a result, a local breakage was observed in the contact portion with the upper indenter 83 on the test piece 80b. On the other hand, Δ in the test of FIG.
In the test piece 80b in which the rapid rise 85a of only the R-bottom was confirmed, the local destruction of the contact portion with the upper indenter 83 was extremely small. From this, it is considered that the above-mentioned initial rise 85 is caused by local fracture due to stress concentration in the vicinity of the point contact with the upper indenter 83 on the upper portion of the test piece 80b. As a result of performing a test on a plurality of test pieces 80b under the test conditions of FIGS. 16 to 18,
In some cases, the above-described initial rise 85 may not be seen, and the value of ΔR-top at the time of the initial rise 85 also varies widely. When the indenters 81 to 83 having a small cross-section radius r are used, the frequency of the initial rise 85 is high, and when the indenters 81 to 83 having a large cross-section radius r are used, the frequency of the initial rise 85 is low. When the initial elevation 85 is not expressed, FIG.
As shown in FIG. 9, a sharp rise is confirmed only in ΔR-bottom.

From the results shown in FIGS. 16 to 19, it can be clearly understood that the fracture on the tensile side of the test piece 80b with respect to the bending strain progresses ahead of other places. Therefore, when an increase in the resistance value is detected in only one of the four conductive fiber bundles 11 of the plastic composite material 10, the side in which the conductive fiber bundle 11 is embedded in the plastic composite material 10 is detected. It can be seen that bending strain acts on the plastic composite material 10 with the side facing the conductive fiber bundle 11 being the compression side through the tensile side and the center of the cross section of the plastic composite material 10. That is, by grasping the distribution of the resistance values of the four conductive fiber bundles 11, it is possible to detect the direction of the strain generated in the plastic composite material 10 and the direction of the acting stress. From the directions of these strains and stresses, the direction of the load causing these strains and stresses can also be grasped.

Further, based on the measured values of the electric resistance of the conductive fiber bundles 11 on the tension side and the compression side, from the comparison,
It is also possible to determine the state of deformation or destruction of the plastic composite material 10. That is, as a result of the above-described bending test (FIGS. 16 to 19), in the process in which the plastic composite material 10 breaks as the bending strain increases, the electrical resistance of the conductive fiber bundle 11 on the pulling side and the compressing side increases. Paying attention to the fact that the relationship between measured values changes in the following four stages,
From the comparison of the measured values of the electrical resistance of the conductive fiber bundle 11 on the compression side, the state of deformation or destruction of the plastic composite material 10 can be determined. The above-mentioned four stages are as follows. (1) Both of the pulling-side and compression-side conductive fiber bundles 11 have not yet been broken, and the pulling-side conductive fiber bundle 1
Only the resistance value of 1 increases with increasing bending strain.
Stages. (2) Both of the pulling-side and compression-side conductive fiber bundles 11 have not yet been broken, and the resistance values of the pulling-side and compression-side conductive fiber bundles 11 increase as the bending strain increases. Stages. (3) The third stage in which only the conductive fiber bundle 11 on the pulling side has broken, and the resistance value of the conductive fiber bundle 11 on the compression side rises as the bending strain increases. (4) The fourth stage in which the conductive fiber bundles 11 on the pulling side and the compressing side have been broken, and the plastic composite material 10 is also buckling like bending.

The change in the relationship between the measured values of the electric resistances of the conductive fiber bundles 11 on the pulling side and the compressing side during the process in which the plastic composite material 10 breaks as the bending strain increases will be described in a little more detail below. To do. As can be seen from FIGS. 16 to 19, when a bending strain is applied to the plastic composite material 10, first, the resistance value of the conductive fiber bundle 11 on the pull side increases the stress of the plastic composite material as the bending strain increases ( (MPa) continues to rise until it reaches the maximum. Here, although the resistance value of the conductive fiber bundle 11 on the compression side may have the above-described initial increase 85, a continuous increase tendency due to an increase in bending strain is not observed. In the vicinity of the maximum stress, specifically, where the bending strain is at or slightly higher than the maximum stress, the resistance of the conductive fiber bundle 11 on the tensile side due to the increase of the bending strain due to the start of the fracture of the plastic composite material 10. The continuous increase of the value temporarily stops (the resistance value may become unstable), but thereafter, the stress starts to decrease due to the further increase of the bending strain of the plastic composite material 10, and the plastic composite material 10 When the breakage becomes apparent, the resistance value of the conductive fiber bundle 11 starts to rapidly increase and reaches infinity (breakage) (in FIGS. 16 to 19, the bending strain is 3.8 to
4.2%). On the other hand, the resistance value of the conductive fiber bundle 11 on the compression side is such that after the stress (MPa) of the plastic composite material becomes maximum and before the conductive fiber bundle 11 on the tension side breaks, the bending strain shows the maximum stress. The ascending tendency, which starts to rise around where it occurs or slightly larger than it, and rises with an increase in bending strain, continues for a while even after the conductive fiber bundle 11 on the tension side is broken. And
The resistance value of the conductive fiber bundle 11 on the compression side is such that, after the conductive fiber bundle 11 on the pull side is broken, the plastic composite material 10 is broken (reduction in stress) due to a further increase in bending strain.
As a result of progressing, the rise becomes sharp and reaches infinity (rupture).

The above-mentioned first to fourth stages can be classified according to the area of the bending strain value. From the start of the increase in the resistance value of the conductive fiber bundle 11 on the pull side to the start of the increase in the resistance value of the conductive fiber bundle 11 on the compression side is the region of the first stage bending strain (first region ε1). The region from the start of the increase in the resistance value of the conductive fiber bundle 11 on the compression side to the time before the breakage of the conductive fiber bundle 11 on the tension side is the region of the second-order bending strain (second region ε2), and the conductivity on the tension side is Sex fiber bundle 1
The region from the rupture of No. 1 to the rupture of the conductive fiber bundle 11 on the compression side is the third stage bending strain region (third region ε3), and the rupture of the electrically conductive fiber bundle 11 on the compression side is the fourth stage. It is a region of bending strain (fourth region ε4). A specific example of the first to fourth regions ε1 to ε4 is shown in FIG.

The states of deformation and breakage of the plastic composite material 10 corresponding to the bending strain regions (first to fourth regions ε1 to ε4) at the first to fourth stages are as follows. In the bending strain (first region ε1) in the region of the first stage, the fracture of the plastic composite material 10 is minute or there is no fracture. At the bending strain in the second stage region (second region ε2), buckling failure of the plastic composite material 10 begins to progress. In the bending strain of the third stage region (third region ε3), the plastic composite material 1
The fracture on the pulling side of 0 is progressing, and the bending strain in the region of the fourth stage (fourth region ε4) causes buckling fracture as if the entire plastic composite material 10 was bent.

From the relationship of the measured values of the electric resistance of the conductive fiber bundle 11 on the pulling side and the compressing side, the plastic composite material 10
If it is possible to identify which of the first to fourth regions ε1 to ε4 the bending strain occurring in
Deformation of the fourth region ε1 to ε4 and the plastic composite material 10,
Depending on the relationship with the state of destruction, the plastic composite material 10
The deformation and destruction status of can be determined. If both the pulling-side and compression-side conductive fiber bundles 11 have not yet been broken, and if an increase in the resistance value is detected only in the pulling-side conductive fiber bundles 11, the bending of the plastic composite material 11 has occurred. The strain is in the first region ε1 and the fracture of the plastic composite material 10 is minute or non-destructive. If both the pulling-side and compression-side conductive fiber bundles 11 have not been broken, and an increase in the resistance value is detected in both the pulling-side and compression-side conductive fiber bundles 11, the plastic composite material 11 is detected.
The bending strain generated in the second region is the second region ε2, and it is assumed that the buckling failure of the plastic composite material 10 has started to progress. If the pulling-side conductive fiber bundle 11 is broken and the increase in the resistance value of the conductive side fiber bundle 11 on the compression side (the resistance value here is smaller than the value at break) is detected, The bending strain generated in the plastic composite material 11 is the third region ε3, and it is assumed that the tensile side of the plastic composite material 10 is being broken. When the breakage of the conductive fiber bundles 11 on the pulling side and the compression side is detected, the bending strain occurring in the plastic composite material 11 is the fourth region ε4, and buckling failure occurs as if the entire plastic composite material 10 was bent. Is assumed to occur. This makes it possible to grasp the degree of destruction of the plastic composite material 10, the degree of deformation or destruction of the structure in which the plastic composite material 10 is installed, etc. without directly observing the plastic composite material 10. .

When an increase in the resistance value is detected in the pair of conductive fiber bundles 11 facing each other through the cross-sectional center of the plastic composite material 10 as in the above-described initial rise 85, two conductive fiber bundles are detected. Although it is unclear which one of 11 is located on the pulling side, bending strain and bending stress with one of the conductive fiber bundles 11 being the pulling side and the other conductive fiber bundle 11 being the compression side are Is working,
The direction of the load that causes these strains and stresses can be roughly understood.

Moreover, the ΔR-bott shown in FIGS.
As for the om, the increase becomes apparent at an extremely early stage (stage where bending strain is small) as compared with the measurement result of FIG.
Compared to the test piece 80a of (b), the test piece 8 of FIG. 14 (c)
0b (however, as shown in FIG. 14C, when the conductive fiber bundle 11 is arranged on the pulling side due to bending deformation of the test piece), the strain and stress detection sensitivity is superior. I understand.

FIG. 8 shows an example in which the strain / stress detection device 42 is used in a management system for a railway line 91.
A fence 40 that performs a function of preventing intrusion of sediment into the railroad track 91 is appropriately installed in a dangerous place near the railroad track 91, such as a slope of natural ground T, and sensing of a sensor unit 41 provided in each fence 40 is performed. The circuits 71 to 74 are connected to the resistance measuring device 60, and the strain / stress detecting device 42 is configured for each fence 40. Although not explicitly shown in FIG. 8, the fence 40 is also continuously provided in the direction along the extending direction of the railroad track 91, and the strain / stress detecting device 42 is formed between the fence 40 and the resistance measuring device 60. Is provided.

In this management system, the resistance measuring device 60 has a plurality of sensing circuits 71 to 74 of the sensor units 41.
Are connected to one of the sensing circuits 71 to 7
When an increase in electrical resistance is detected at 4, the management office 6
2, the position information of the corresponding sensor unit 41 in which the sensing circuit in which the increase of the electric resistance is detected (abnormality detection) exists, and the resistance measurement values of the four sensing circuits 71 to 74 related to the corresponding sensor unit 41 Information is output by a panel display or voice. Since the location of the abnormality can be specified by the position information of the sensor unit 41, there is an advantage that a worker dispatched to resolve the abnormality can reduce the time required to find the location of the abnormality. In addition, the resistance measurement value information of the four sensing circuits 71 to 74 related to the sensor unit 41 that has detected the abnormality can be used for grasping the occurrence state of the abnormality and so on. There are advantages such as quick preparation. For example, when it is known from the position information at the time of abnormality detection that the location where the abnormality occurs is the fence 40 provided on the slope T of the natural ground T, the four sensing circuits 71 to 74 of the sensor unit 41 are detected. Among them, the increase in the electric resistance is detected on the lower side of the plastic composite material 10 (Fig. 6 (a),
If only the sensing circuit 71 to which (b) the lower side) conductive fiber bundle 111 is connected, the plastic composite material is applied by some external force such as the fall of the fallen tree 44 into the fence 40 as shown in FIG. It is assumed that 10 is subjected to downward bending deformation (bending deformation due to downward pressing of a part of the plastic composite material 10 in the longitudinal direction).
In addition, the fact that the increase in the electric resistance is detected is shown in FIG.
(A), (b) If there is only the sensing circuit 72 to which the conductive fiber bundle 113 on the left side is connected, for example, as shown in FIG. 8, the fence 40 is formed by the earth and sand T1 and the rock T2 that have fallen on the slope of the natural ground T. It is assumed that is deformed by being pressed. Moreover, if an increase in the resistance value is detected in all of the four sensing circuits 71 to 74 of the sensor unit 41 that has detected the occurrence of an abnormality, it is assumed that the fence 40 has largely collapsed. Therefore, by procuring equipment such as a cutting machine for the fallen tree 44 and a heavy machine for moving earth and sand in response to such an assumed abnormality, it is possible to shorten the work time until the abnormality is resolved.

By the way, a strain / stress detecting device having a sensor unit assembled by using a plurality of plastic composite materials 10 has four sensing circuits 7 of the sensor unit.
The distribution of the resistance values of 1 to 74 is adapted to detect the direction of strain and stress, so that the plastic composite material 1
The combination of the conductive fiber bundles 11 connected between 0 becomes a problem (as an example, the sensor unit 41 of FIG.
See). The electrical connection component 20 illustrated in FIGS.
4 to 4 conductive fiber bundles 11 between the plastic composite materials 10
You can easily connect all at once. In this electrical connecting component 20, connectors C1 and C2, which are connected to an end portion of the plastic composite material 10 and are electrically connected to an energizing terminal portion, are provided with an electric wire 21.
It is attached to both ends of. Since the connectors C1 and C2 have the same configuration, both connectors C1 and C2
When describing the configuration common to C2, it may be referred to as "connector C".

This connector C has a movable terminal portion 23 and a biasing member 24 inside a ring portion 22 which constitutes a female screw.
(Here, a spring, which may be referred to as a “spring 24” hereinafter). The movable terminal portion 23 is rotatable in the ring portion 22 about the central axis of the ring portion 22 and is movable along the central axis of the ring portion 22 in the front surface 27 of the terminal body 27.
A positioning pin 25 is provided on the a side (the left side in FIGS. 3A and 3B).
And four pin terminals 26a to 26d are projected. However, in the terminal body 27, the pin terminal 26a
The electrical insulation between ~ 26d is secured. To connect the connector C to the end of the plastic composite material 10, first, the positioning pin 25 is inserted into the positioning hole 12b formed in the end surface 12a of the plastic material 12, and then the threaded portion 17 is joined to the ring portion. 22 should be screwed in. Here, each of the pin terminals 26a to 26d corresponds to the terminal portion main body 2
The protrusion length from 7 is uniform, but the positioning pin 2
The protrusion length of 5 from the terminal portion main body 27 is from each pin terminal 26a to
It is several mm to ten and several mm longer than 26d. Moreover, in the state before connection, the movable terminal portion 23 is connected to the front end of the ring portion 22 in the connection direction by the spring 24 (see FIG. 3A).
(B) The positioning pin 25 is pushed out to the left side and the positioning pin 25 projects from the ring portion 22 to the front side in the connecting direction. 12b and the positioning pin 25 can be efficiently checked while visually confirming.

When the positioning pin 25 is inserted into the positioning hole 12b of the end surface 12a of the plastic material 12, the four pin terminals 26a to 26d of the connector 20 are individually attached to the four energizing terminal portions 14 of the end surface 12a of the plastic composite material 12. Be positioned at. Then, the screw portion 17
As the screws are screwed in, the pin terminals 26a to 26d are brought into contact with the energizing terminal portions 14 provided individually for the conductive fiber bundles 11 in a one-to-one correspondence. Also, the ring portion 2 to the screw portion 17
By screwing in 2, the movable terminal portion 23 becomes the spring 2
4 is pressed toward the rear side of the ring portion 22 while being compressed, and the urging force of the spring 24 causes the pin terminals 26a to
26d acts on the energizing terminal portion 14 against the energizing terminal portion 14, and therefore the energizing terminal portion 14 of each of the pin terminals 26a to 26d.
A connection state in which electrical conduction can be established between and is reliably ensured.

As shown in FIG. 2, each connector C1, C2
A display 28a indicating the direction of the movable terminal portion 23 is formed on the side surface of the boot portion 28 protruding from the movable terminal portion 23 to the rear end of the ring portion 22. As shown in the schematic view of FIG. 3C, in the electrical connection component 20, the connectors C1 and C2 are provided.
Positioning pin 25 and pin terminals 26a to 26d in
And the display 28a have the same positional relationship with each other, and the display 2
8a is a wire 2
It is connected via one core wire 21a-21d. Therefore, the two connectors C1 and C2 of the electrical connection component 20 are
The conductive fiber bundle 11 of the plastic composite material 10
When connected to each other, among the conductive fiber bundles 11 of each plastic composite material 10, the conductive fiber bundles 11 having the same positional relationship to the display 28a are connected via the core wires 21a to 21d of the electric wire 21.

FIG. 3C shows the electric connecting part 20 as shown in FIG.
(A), (b), the case where it utilized for the connection between the adjacent plastic composite materials 10 which comprise the sensor unit 41 illustrated in FIG. 7 is illustrated. The two connectors C1 and C2 of the electrical connection component 20 are connected to the plastic composite material 10 respectively.
After connecting with the conductive fiber bundle 11 of FIG. 6, if the indications 28a of the connectors C1 and C2 are oriented to the same side, for example, the right side of FIG. The orientation of each plastic composite material 10 connected via the electrical connection component 20 is determined. In this state, as described above, the conductive fiber bundles 11 having the same positional relationship with respect to the display 28a are connected to the core wires 21a to 2 of the electric wire 21.
Since they are connected via 1d, for example, the conductive fiber bundles 111 on the lower side of each plastic composite material 10 are connected via the core wire 21a of the electric wire 21, and the conductive fibers on the upper side of each plastic composite material 10 are connected. The bundles 112 are connected to each other via the core wire 21b of the electric wire 21.

The lattice-shaped sensor unit 50 of the strain / stress detection device 51 illustrated in FIG.
The intersections of 0s are fixed by the fixed joint 53 (see FIG. 10), and the sensor unit 50 itself has excellent strength. In this sensor unit 50 as well, the sensing circuit formed by connecting the conductive fiber bundles 11 to each other between the plastic composite materials 10 constituting the sensor unit 50 is formed. Same as device 42. Specifically, this sensor unit 50
Is a joint 5 of a plurality of plastic composite materials 10 (hereinafter referred to as "vertical members 54") arranged in the vertical direction (up and down in FIG. 9).
5. One continuous vertical unit 50A assembled on one assembly plane by connecting through the L-shaped joint 56 and the connecting horizontal member 57, and a plurality of plastics arranged in the horizontal direction (left and right in FIG. 9) A continuous single piece in which the composite material 10 (hereinafter referred to as "horizontal member 58") is connected through a joint 55, an L-shaped joint 56, and a connecting vertical member 59 and assembled on an assembly plane parallel to the assembly plane of the vertical unit 50A. The vertical unit 50B of FIG. However, the horizontal unit 50B is constructed so as to be displaced from the vertical unit 50A toward the back side of the paper in FIG.
They are connected (see below) (see FIG. 10). The connecting horizontal members 57 and the connecting vertical members 59 are the plastic composite material 10 having a shorter length than the plastic composite material 10 forming the vertical members 54 and the horizontal members 58.

Connection end 5 of the vertical / horizontal units 50A, 50B
0a and 50b correspond to both ends of the sensing circuit of the sensor unit 50, and the plastic composite 1
It is a connector for connecting the wiring between the conductive fiber bundle 11 of 0 and the resistance measuring device 60. Vertical unit 50A
Of the horizontal unit 50B and the terminal end of the lateral unit 50B facing the connecting end 50b of the horizontal unit 50B.
Thus, the conductive fiber bundles 11 are connected to each other. As a result, both units 50 are connected via this unit connecting portion 50c.
The conductive fiber bundles 11 of the respective plastic composite materials 10 constituting A and 50B are electrically connected to each other to form a sensing circuit for connecting the connection ends 50a and 50b of the vertical and horizontal units 50A and 50B. .

The joint 55, the L-shaped joint 56 and the unit connecting portion 50c electrically connect the conductive fiber bundles 11 of the plastic composite material 10 which are the vertical members 54, the horizontal members 58, the connecting horizontal members 57 and the connecting vertical members 59. Connect to. These joints 55, L-shaped joints 56, unit connecting portions 50c
For example, when sufficient strength is secured in the sensor unit by the fixed joint 53 or the like, for example, the above-mentioned electrical connection component 20 or the like can be adopted, but in the case where the sensor unit itself is used as a structure, the strength is secured. Therefore, it is preferable to also serve as a joint for fixing the plastic composite materials 10. However, even when the joint type joint 55, the L-shaped joint 56, and the unit connecting portion 50c are adopted, a configuration in which the four conductive fiber bundles 11 of the plastic composite material 10 can be connected in a desired combination is adopted.

As the joint type joint 55, the L-shaped joint 56, and the unit connecting portion 50c (hereinafter, these may be collectively referred to as "electrical connecting part 20A"),
For example, as schematically shown in FIG. 20, a pair of connectors C of the electrical connection component 20 are provided at both ends of one joint pipe 29.
The configuration is such that the ring portions 22 of 1 and C2 are rotatably provided, and the movable terminal portion 23 and the urging member 24, which are movable along the central axis of the ring portion 22, are housed inside each ring portion 22. It is possible. However, between the joint pipe 29 and the movable terminal portion 23, the ring portion 22 of the movable terminal portion 23 is moved by the movement of the movable terminal portion 23 along the guide member 29b protruding from the joint pipe 29 into the ring portion 22. The movement in the central axis direction is permitted, and the rotation with respect to the joint pipe 29 is restricted. In this case, the combination or position between the conductive fiber bundles 11 of each plastic composite material 10 connected via the electrical connection component 20A is indicated by the display 29a provided on the joint pipe 29 or the display provided on each plastic composite material 10. Make sure you understand the relationship.

The four conductive fiber bundles 11 are connected to each other between the plastic composite materials 10 constituting the sensor unit 50 by the four sensing circuits constituted by the connection of the conductive fiber bundles 11 to each other. Strain / stress detector 51
Are adjusted so that the arrangement is suitable for detecting the strain / stress to be detected. For example, in the wall 52 illustrated in FIG. 11, the vertical unit 50A and the horizontal unit 50B are the wall 52.
Of the sensor units 50 so that they are connected in the thickness direction of the sensor unit 50.
The vertical unit 50A is installed to efficiently detect the strain and breakage of the wall 52 and the direction of the strain and stress.
The four conductive fiber bundles 11 constituting all the vertical members 54 are arranged in the same arrangement (for example, arranged in the thickness direction side of the wall 52 and on both sides (left and right) in the horizontal direction orthogonal to the thickness direction side), The arrangement of the four conductive fiber bundles 11 is made to be the same in all the horizontal members 58 constituting the horizontal unit 50B (for example, they are arranged on both sides in the thickness direction of the wall 52 and in the vertical direction), and further, over the entire length of the vertical unit 50A. The arrangement of the sensing circuits is unified (for example, one of a pair of sensing circuits facing each other in each vertical member 54 is unified on one side in the thickness direction of the wall 52, and the other is arranged on the other side in the thickness direction of the wall 52), and the horizontal unit 50B. However, it is conceivable to unify the arrangement of the sensing circuits over the entire length (for example, one of the pair of sensing circuits facing each other in each lateral member 58 is on the upper side and the other is on the lower side).

The specific structure of the sensor unit is not limited to that illustrated in FIGS. 9 and 10, and the structure, scale, etc. can be freely changed by connecting the plastic composite material 10. Further, by combining the conductive fiber bundles 11 connected between the plastic composite materials 10, it is possible to freely change the arrangement of the sensing circuits in the sensor unit so as to advantageously detect the target strain or stress. For example, detecting local strain and stress in large structures such as high-rise buildings,
When this strain / stress detection device is applied to the detection of strain or stress acting on a dome roof concrete wall, the layout of the sensing circuit is set to be advantageous for the detection of strain or stress.

By the way, this plastic composite material 10
Since the conductive fiber bundle 11 can generate heat by energization, it can also be used as a heating element. For example,
As shown in FIG. 12, when the sensor unit 50 of the strain / stress detection device 51 itself is used as a fence-shaped sensor body that also serves as a snow stop fence, the sensor unit 50 protects the fallen snow block from falling. In addition to having a function as a fence and a sensor body for detecting the collapse of snowflakes, it can also function as a snowmelt body for melting snowflakes.
If, for example, a sensor unit consisting of a large number of plastic composite materials connected to each other is installed on a bridge other than a snow stop fence, in addition to the function as a sensor body for detecting strain / stress of the bridge, It can also function as a snow melting body that melts snow adhering to the bridge, and can prevent the bridge from being distorted due to snow adhering. Furthermore, for example, if a sensor unit is constructed in a grid or blind shape so as to block the entrance of a restricted area installed at a construction site and it functions as an intruder detection sensor, the entrance will be buried in snow due to snow melting. There is also an advantage that it can be prevented. As the energizing means for energizing the conductive fiber bundle 11, for example, a device that also serves as the resistance measuring device 60 may be adopted, that is, energizing terminal portions at both ends of the resistance measuring device 60 and the sensor unit (that is, each of the sensor units). Sensing circuit terminal)
It is preferable in that it can share a connection circuit for connecting between and. Further, a configuration in which the resistance measuring device 60 and the energizing means are selectively connected to the connection circuit via a changeover switch is also preferable in that the connection circuit can be shared.

21 (a) to 21 (e) and FIG. 22 (a) to
(E) shows an example of a cross-sectional structure of the plastic composite material according to the present invention. The plastic composite materials exemplified here all have a circular cross section. 21 (a) to 21 (e) show an example in which the conductive fiber bundles 11 are arranged on the outer peripheral portion (near the side surface) of the cross section of this plastic composite material and embedded in the plastic material 12, and FIG. An example in which the conductive fiber bundles 11 are distributed substantially uniformly in a plurality of locations in the circumferential direction of the cross section, (b) is a cross section of the plastic composite material 10 illustrated in FIG. (C) is an example in which three conductive fiber bundles 11 are distributed substantially uniformly at a plurality of locations in the circumferential direction of the cross section, and (d) is 2
An example in which the conductive fiber bundles 11 of the book are arranged to face each other in the radial direction of the cross section,
(E) is an example in which one conductive fiber bundle 11 is arranged on the outer peripheral portion (near the side surface) of the cross section of the plastic composite material. FIG. 22
(A) to (e) show positions of a half of the radius from the center of the cross section of this plastic composite material to the outer circumference (Fig. 22).
It is an example in which the conductive fiber bundle 11 is arranged in the virtual line 18 in (a) to (e) and embedded in the plastic material 12,
(A) is an example in which eight conductive fiber bundles 11 are distributed substantially uniformly in a plurality of locations in the circumferential direction of the cross section, and (b) is four conductive fiber bundles 11 are substantially evenly distributed in a plurality of locations in the circumferential direction of the cross section. In the example, (c) is an example in which the three conductive fiber bundles 11 are evenly distributed in a plurality of locations in the circumferential direction of the cross section, and (d) is 2
An example in which the conductive fiber bundles 11 of the book are arranged to face each other in the radial direction of the cross section,
(E) is an example in which only one conductive fiber bundle 11 is arranged.

Here, FIGS. 21 (a), (b), and FIG.
In the cross-sectional structures shown in (a) and (b), since there is almost no directivity for the strain or stress to be detected, it is possible to detect bending strain and bending stress in various directions. In addition, in the plastic composite material having this cross-sectional structure, when the occurrence of bending strain due to an increase in the resistance value of the conductive fiber bundle 11 is detected, the resistance values of the conductive fiber bundles 11 are compared and By grasping the distribution and the position of the conductive fiber bundle 11 that greatly increases, there is also an advantage that the directions of strain and stress can be grasped and judged in more detail and accurately.

21C to 21E and 22C to 22C.
The plastic composite material having the cross-sectional structure of (e) is suitable for detecting strain and stress in a specific direction because the directionality of strain and stress detection sensitivity is strong. There is an advantage that it is difficult to erroneously detect stress. In this plastic composite material, the conductive fiber bundle 11 is arranged at a position on the pulling side when bending distortion is applied to the plastic composite material in correspondence with the direction of strain or stress to be detected during construction. Install in the orientation. That is, FIG. 21 (c), (d), FIG. 22 (c),
The plastic composite material having the sectional structure of (d) is installed so that one of the plurality of conductive fiber bundles 11 is on the pulling side. The plastic composite material having the cross-sectional structure shown in FIGS. 21 (e) and 22 (e) is embedded in the plastic material 1
The book is installed so that the conductive fiber bundle 11 of the book is on the pulling side.

Compared with the cross-sectional structure illustrated in FIGS. 22A to 22E, the cross-sectional structure illustrated in FIG. 21A to FIG. It is possible to secure a large distance from the center of the cross section of the material. However, when bending strain is applied to the plastic composite material, the cross-sectional structures illustrated in FIGS.
As compared with the cross-sectional structures illustrated in FIGS. 22A to 22E, the conductive fiber bundle 11 on the pulling side is efficiently strained, and the bending strain can be detected more sensitively.
In addition, a plurality of conductive fiber bundles 11 are embedded in FIG.
In comparison between (a) to (d) and FIGS. 22 (a) to (d),
The cross-sectional structures of FIGS. 21 (a) to 21 (d) ensure a larger distance between the conductive fiber bundle on the tensile side and the conductive fiber bundle on the compression side of the plastic composite material subjected to bending strain. Therefore, when bending strain occurs in the plastic composite material, the difference in the resistance value of the conductive fiber bundle on the tensile side and the compression side becomes more apparent, and the direction of strain and stress of the plastic composite material can be detected. Can be performed more reliably.

It is needless to say that the present invention is not limited to the above-mentioned embodiment and various modifications can be made. For example, the cross-sectional structure of the plastic composite material is shown in FIG.
The configurations are not limited to those illustrated in (a) to (e) and FIGS. 22 (a) to (e), and other configurations can be adopted. Also,
The cross-sectional shape (cross-sectional outer shape) of the plastic composite material is not limited to a circular shape, and for example, a regular polygon such as a square or a regular hexagon, an ellipse, a rectangle, or the like can be used.

Further, in FIG. 7 etc. of the above-mentioned embodiment (application example to a fence), a plurality of plastic composite materials are connected one-dimensionally, and in FIG. 9 etc. a plurality of plastic composite materials are two-dimensionally connected. Although a configuration in which a plurality of plastic composite materials are connected three-dimensionally can be adopted as the sensor unit constituting the strain / stress detection device according to the present invention. Also in this case, by connecting the conductive fiber bundles between the plastic composite materials forming the sensor unit, a sensing circuit is formed in which the conductive fiber bundles of the plurality of plastic composite materials are electrically connected in series. Is more preferable.

The energizing terminal portion is not limited to the conductive layer formed on the end face in the longitudinal direction of the plastic material, and for example, the conductive fiber bundle itself projected on the end face in the longitudinal direction of the plastic material or the end of the conductive fiber bundle. A pin terminal connected to
Various configurations such as the tip of the conductive fiber bundle exposed in the recess depressed from the longitudinal end surface of the plastic material can be adopted. It goes without saying that a connector or the like connected to the energizing terminal portion also has a structure capable of being electrically connected in correspondence with the specific configuration of the energizing terminal portion.

The strain / stress detection device of the present invention is not limited to the above-mentioned fences and strain detection of large structures such as buildings, but can also be used for strain detection of natural slopes. For example, by embedding a plastic composite material in multiple locations on a rock slope (cliff, etc.) where there is a risk of collapse, and monitoring the increase in the electrical resistance of the conductive fiber bundle of this plastic composite material, It can be used to detect the occurrence of strain as a precursory phenomenon before the collapse of, and to detect the collapse.

[0064]

According to the conductive fiber bundle-containing plastic composite material of the present invention, a conductive fiber bundle is embedded and integrated in a rod-shaped plastic material along the longitudinal direction of the plastic material. Therefore, it is possible to continuously form by pultrusion molding and extrusion molding, and the cost can be reduced. Also, by detecting an increase in the electrical resistance of the conductive fiber bundle, it is possible to detect the occurrence of bending strain in this conductive fiber bundle-containing plastic composite material, but avoid the conductive fiber bundle from avoiding the central portion of the cross section of the plastic material. Since it is offset to the outside, when a bending strain occurs in which the embedded position of the conductive fiber bundle is the tensile side of the bending deformation of the conductive fiber bundle-containing plastic composite material, the conductive fiber bundle is broken. The electric resistance is likely to increase due to the progress of, and the detection sensitivity of the bending strain is improved. Furthermore, in the conductive fiber bundle-containing plastic composite material having a configuration (claims 3 and 4) in which a plurality of (for example, four) conductive fiber bundles are dispersed and arranged in the circumferential direction of the cross section, the electrical conductivity of each conductive fiber bundle is increased. From the distribution of resistance,
The direction of strain or stress can also be determined and detected (claim 8).

According to the strain / stress detection device of the present invention, a plurality of conductive fiber bundle-containing plastic composite materials constituting the sensor unit are externally attached to a structure whose strain or stress is to be detected by burying or the like. Distortion and stress generated in the structure can be achieved by installing the individual sensor units individually into the structure, or by simply providing the structure of the sensor unit assembled so that the structure itself can function as the structure. It becomes possible to detect. If the sensor unit is composed of multiple plastic composite materials containing conductive fiber bundles, it can be used in a wide range of sizes and structures by selecting the size and number of plastic composite materials containing conductive fiber bundles. It is possible to install it with high versatility. Also,
It is also possible to construct a sensor unit which is assembled one-dimensionally, two-dimensionally or three-dimensionally by connecting and fixing a plurality of plastic composite materials containing conductive fiber bundles. In this case, the sensor unit itself is a structure. It is also possible to externally attach to the structure as a reinforcing material of the structure, or to integrally provide it by embedding or the like. The sensor unit assembled so that it can function as a structure itself can be freely designed in terms of scale, shape, structure, etc. by selecting the size, number, etc. of a plurality of conductive fiber bundle-containing plastic composite materials. There are advantages such as.

[Brief description of drawings]

FIG. 1 is a plastic composite material containing a conductive fiber bundle of the present invention (hereinafter sometimes referred to as “plastic composite material”)
FIG. 4A is a front view, and FIG. 6B is a sectional view taken along the line AA of FIG.

FIG. 2 is a perspective view showing an electrical connection component having a connector configured to be screwed into a threaded portion at a longitudinal end portion of the plastic composite material of FIG.

3 (a) to 3 (c) are cross-sectional views showing a configuration of the electrical connecting component of FIG. 2, in which FIG. 3 (a) is before connecting the current-carrying terminal portion of the plastic composite material to the connector, and FIG. Shows a connected state, and (c) shows a state in which a pair of plastic composite materials are connected.

FIG. 4 is a perspective view showing a movable terminal portion of the electrical connecting component of FIG.

FIG. 5 is a diagram showing an example of the manufacturing equipment for the plastic composite material of the present invention, showing the manufacturing equipment for pultrusion molding.

6A and 6B are diagrams showing a state in which the plastic composite material of FIG. 1 is integrally attached to a fence, wherein FIG. 6A is a sectional view and FIG. 6B is a perspective view.

7 is a diagram schematically showing a strain / stress detection device in which a resistance measuring device is connected to the conductive fiber bundle of the plastic composite material of FIG.

[Fig. 8] Structures (fences) installed on multiple slopes
FIG. 3 is a diagram schematically showing a strain / stress detection device configured by connecting a sensor unit integrally provided in each and a resistance measuring device.

FIG. 9 is a plan view showing a sensor unit having a configuration in which a large number of plastic composite materials are connected to each other and assembled into a lattice shape.

10 is a perspective view showing a structure for connecting and fixing a vertical member and a horizontal member that constitute the sensor unit of FIG.

FIG. 11 is a perspective view showing a wall (concrete wall) in which the sensor unit of FIG. 9 is built in as a framework.

FIG. 12 is a diagram showing a state in which the sensor unit itself of FIG. 9 is erected on the slope of the ground T as a fence-shaped sensor body that also serves as an earth retaining fence, a snow retaining fence, and the like.

FIG. 13 is a diagram schematically showing the strain / stress detection device of FIG. 7, in which conductive fiber bundles are electrically connected so as to be electrically conductive between a plurality of plastic composite materials of a sensor unit. 3 shows a plurality of sensing circuits that have been processed.

14A and 14B are views showing a bending test of a plastic composite material, wherein FIG. 14A is an installation state of the plastic composite material on a test jig, and FIGS. 14B to 14C are cross-sectional structures of the plastic composite material of the test piece. FIG.

15 is a graph showing the test results of the test piece of the comparative example in the bending test of FIG.

16 is a graph showing the test results of the test piece of the example in the bending test of FIG.

FIG. 17 is a graph showing the test results of the test piece of the example in the bending test of FIG. 14, showing a case where the span L between the lower indenters is changed.

FIG. 18 is a graph showing the test results of the test piece of the example in the bending test of FIG. 14, showing a case where the span L between the lower indenters and the indenter cross-sectional radius are changed.

FIG. 19 is a graph showing the test results of the test piece of the example in the bending test of FIG. 14, showing the case where the span L between the lower indenters and the indenter cross-sectional radius are changed.

20 is a diagram schematically showing an example of an electrical connection component used in the sensor unit of FIG.

21A to 21E are cross-sectional views showing another embodiment of the cross-sectional structure of the plastic composite material according to the present invention.

22 (a) to (e) are cross-sectional views showing another embodiment of the cross-sectional structure of the plastic composite material according to the present invention, and in particular, the position of half the radius of the plastic composite material from the center of the cross-section. An example in which a conductive fiber bundle is arranged is shown below.

FIG. 23 is a sectional perspective view showing an example of a conventional plastic composite material.

[Explanation of symbols]

10 ... Plastic composite material containing conductive fiber bundle, 11, 1
11-114, 11b, 11t, 11cf, 11cb ...
Conductive fiber bundle (carbon fiber bundle), 12 ... Plastic material,
13 ... Reinforcing fiber bundle (glass fiber) 14 ... Current-carrying terminal portion,
34 ... bar material (plastic composite material containing conductive fiber bundles),
41 ... Sensor unit, 42 ... Strain / stress detection device, 5
0 ... Sensor unit, 51 ... Strain / stress detection device, 54
... Plastic composite material containing conductive fiber bundle (vertical member), 57
... Plastic composite material containing conductive fiber bundle (connecting cross member),
58 ... Plastic composite material containing conductive fiber bundle (horizontal material),
59 ... Plastic composite material containing conductive fiber bundle (connecting vertical member), 60 ... Resistance measuring instrument.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Tetsuo Yamaguchi             1-5-9 Nakagawa-chuo, Tsuzuki-ku, Yokohama-shi, Kanagawa             −1002 F term (reference) 2F063 AA25 BA17 DA02 DA05 DD07                       EC02 EC05 KA01                 2F076 BA01 BB09 BD02 BD10 BD17                       BE01

Claims (8)

[Claims] 1. One or a plurality of conductive fiber bundles are embedded and integrated in a rod-shaped plastic material in parallel with the longitudinal direction of the plastic material, and the conductive fiber bundles are arranged in the longitudinal direction of the plastic material. It is arranged at a position shifted to the outside while avoiding the central portion of the cross section orthogonal to, and at the both ends in the longitudinal direction of the plastic material, the energizing terminal portions of the conductive fiber bundle are provided. A plastic composite material containing a conductive fiber bundle. 2. The plastic material is formed to have a circular cross section, and the plastic material is formed at a position ½ of the radius of the cross section from the center of the cross section orthogonal to the longitudinal direction of the plastic material to the outer periphery or an area outside the radius. The conductive fiber bundle-containing plastic composite material according to claim 1, wherein the conductive fiber bundle is arranged. 3. A plurality of conductive fiber bundles are substantially evenly distributed and arranged at a plurality of locations in a circumferential direction of a cross section orthogonal to the longitudinal direction of the plastic material. The conductive fiber bundle-containing plastic composite material described. 4. The conductive fiber bundles are arranged at four locations which are substantially evenly distributed in a circumferential direction of a cross section orthogonal to the longitudinal direction of the plastic material. The electrically conductive fiber bundle-containing plastic composite material according to any one of claims 1. 5. The conductive fiber bundle-containing plastic composite material according to claim 1, wherein a plurality of conductive fiber bundles embedded in the plastic material have a constant cross-sectional shape. . 6. In addition to the conductive fiber bundle, a reinforcing fiber bundle having a larger elongation than the conductive fiber bundle is embedded in the plastic material so as to extend substantially along the conductive fiber bundle. The conductive fiber bundle-containing plastic composite material according to any one of claims 1 to 5, wherein 7. A plurality of conductive fiber bundle-containing plastic composite materials according to claim 1 are used, and conductive fiber bundles are formed between the conductive fiber bundle-containing plastic composite materials. A sensor unit that is electrically connected so that a plurality of conductive fiber bundles of a plastic composite material containing conductive fiber bundles are connected in series, and a resistor connected to each energizing terminal section at both ends of this sensor unit. A strain / stress detection device comprising: a measuring instrument. 8. The electric resistance of a plurality of conductive fiber bundles of the conductive fiber bundle-containing plastic composite material according to claim 3 or 4, and the resistance value of a part of the conductive fiber bundles is measured. When the rise of the conductive fiber bundle is detected, the direction of the strain generated in the conductive fiber bundle-containing plastic composite material is determined from the distribution of resistance values measured for the conductive fiber bundles. .