JP2013096821A - Fatigue degree detecting strain gauge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fatigue degree detecting strain gauge for measuring strain of a structural material and predicting fatigue breakdown locally generated in the structural material.SOLUTION: The fatigue degree detecting strain gauge includes: a strain detection part 130 in which a strand 131 and an adjacent strand are connected through a folding tab 132; a folding line part 140 connected in series to the strain detection part 130 in a state that a strand 141 and an adjacent strand are connected through a folding tab 142; a bypass part 160 forming a route different from the folding line part 140 and the strain detection part 130 and configured such that one end is connected to one terminal part through the folding tab 141 of the folding line part 140 and the strain detection part 130 and other end is connected to the other terminal part; and a fatigue degree detection part 150 connected to the folding tab 142 of the folding line part 140. Respective folding tabs are connected to the bypass part 160 through the fatigue degree detection part 150, and the fatigue degree of the structural material to which the fatigue degree detecting strain gauge is stuck is detected from a degree of rupture of the fatigue degree detection part 150.

Description

  The present invention relates to a fatigue level detecting strain gauge capable of measuring strain of a structural material and predicting in advance signs of fatigue fracture locally occurring in the structural material.

  For example, a strain gauge for measuring the strain of a structural material is generally known (see Patent Document 1). This strain gauge attaches a plate-like base with a strain sensing element and an alignment mark to the exact position of a strain generating body with a positioning mark. The degree of strain accumulation is calculated to predict signs of fatigue failure of structural materials.

JP 2010-169616 A

  The above-described strain gauge generally has sufficient mechanical properties equivalent to a mechanical structural material. Therefore, in general structural materials such as beams, columns, bridge piers, steel towers, bridges, etc., whose mechanical strength and fatigue strength are lower than those of mechanical structural materials, a single strain gauge is used at the base, welded portion, and notched portion of a beam that is particularly susceptible to fatigue failure. Is used as a strain sensor for fatigue detection, strain output trends must be collected over a long period of time via a data logger, etc., and the amount of data for accumulating the detected data becomes enormous. And processing is difficult.

  In addition, even when trying to use a single strain gauge for a part where a stress concentration is likely to occur due to a sudden change in the cross-sectional shape of a welded part or a structural material having a relatively low fatigue strength of a mechanical structural material used in an industrial machine, for example. Problems similar to those of the general structural material described above arise.

  Therefore, in order to avoid such a problem, a fatigue degree detection strain gauge 900 related to the present invention as shown in FIG. 9 has been proposed, which is not yet known at the time of filing the present invention. The strain gauge 900 includes a strain detection unit 930, a conduction unit 940 connected in series with the strain detection unit 930, and a fatigue level detection unit 950 connected in parallel with the conduction unit 940. When the folded tab 952 and the strand 951 are broken by fatigue, the resistance of the strain gauge is increased, and the progress of fatigue is detected stepwise.

  However, in the case of the fatigue detection strain gauge 900 having such a configuration, if an attempt is made to detect the fatigue when the fatigue of the structural material has not progressed so much, the fatigue detection unit breaks in response to the slight fatigue. Thus, it is necessary to increase the length of the folded tab, and the breakage position of the fatigue level detection unit 950 moves away from the stress concentration portion, which makes it unsuitable for rapid and accurate detection of the fatigue level.

  Further, in the case of the fatigue level detection strain gauge 900, since the fatigue level detection unit 950 is formed on the terminal side, when the fatigue level detection unit 950 is arranged at a place where stress concentration locally occurs, the terminal unit 921 is provided. , 922 (920) are also arranged in the vicinity. As a result, stress is generated also at, for example, the solder joint portion of the terminal portion 920 with the stress concentration of the structural material, which is not preferable from the viewpoint of maintaining the reliability of the fatigue degree detection strain gauge 900 for a long period of time.

  On the other hand, if the fatigue degree detection strain gauge 900 is arranged in a state where the terminal part 920 is separated from the local stress concentration part so that the terminal part 920 is not affected by the stress concentration, the fatigue degree detection part 950 is also a stress concentration part. Therefore, it is not preferable from the viewpoint of detecting the degree of fatigue quickly and accurately.

  An object of the present invention is to provide a fatigue degree detection strain gauge capable of measuring strain of a structural material and predicting a fatigue fracture sign locally generated in the structural material in advance and accurately.

In order to solve the above-described problem, a fatigue degree detection strain gauge according to claim 1 of the present invention is provided.
A fatigue degree detection strain gauge capable of appropriately performing the fatigue degree of a structure by detecting an electrical change in the resistance value of a resistor,
A strain detecting unit in which the strand and the adjacent strand are arranged in parallel and connected via a folded tab;
A strand and an adjacent strand are arranged in parallel and connected via a folded tab, and a folded line portion connected in series with the strain detector,
The return line part and the strain detection part form a separate path, and one end is connected to one terminal part of the terminal part via a return tab and a strain detection part of the return line part, and the other end is the other end of the terminal part. A bypass section connected to the terminal section of
A fatigue degree detection unit connected to each folded tab arranged in parallel to the folded line portion;
Each folded tab arranged in parallel is connected to the bypass part via the fatigue detection part,
The fatigue level of the structural material to which the fatigue level detection strain gauge is attached is detected from the degree of breakage of the fatigue level detection unit.

  With the fatigue level detection strain gauge according to claim 1 having such a configuration, the fatigue level detection unit can be disposed at a place where stress concentration locally occurs in the structural material, and the fatigue level can be quickly and accurately determined. Detection is possible. In particular, since the parallel folded tabs are connected to the bypass part via the fatigue detection part, the bypass parts can be extended in parallel to the end parts of the parallel folded parts via the fatigue detection part, respectively. . As a result, the fatigue level detection unit can be disposed as close as possible to the front end side of the film-like member, so that the progress of fatigue of the structural material can be detected more accurately.

  In addition, since it is not necessary to lengthen the length of the folded tab for fatigue level detection as in the related application of the present application, the length in the longitudinal direction of the film-like member of the fatigue level detection unit can be reduced to the tip side, As a result, the fatigue level detection unit can be brought closer to the stress concentration unit.

  In addition, since the fatigue level detection part is not formed on the terminal part side, even if the fatigue level detection part is arranged in a place where stress concentration occurs locally, for example, stress is applied to the solder joint of the terminal part due to the stress concentration. This does not adversely affect the fatigue detection strain gauge itself.

  Further, in order to predict the signs of fatigue failure of the structural material, it is not necessary to collect strain output trends over a long period of time, and the management and processing of an enormous amount of data are not bothered. Further, when the fatigue level detecting portion breaks due to fatigue, the resistance value of the fatigue level detecting strain gauge suddenly increases, and when it changes stepwise, fatigue fracture of the structural material can be easily predicted.

Moreover, the fatigue degree detection strain gauge according to claim 2 of the present invention is the fatigue degree detection strain gauge according to claim 1,
Instead of connecting one end of the bypass part to one terminal part of the terminal part via the return tab of the return line part and the strain detection part, one end of the bypass part is connected via the return tab of the return line part. While being connected to one terminal part, the said distortion | strain detection part is arrange | positioned along with the return | turnback line part and the said terminal part along with the longitudinal direction, It is characterized by the above-mentioned.

  In addition to the action of claim 1, one end of the bypass portion is connected to one terminal portion via the return tab of the return line portion, and both ends of the strain detection portion are directly connected to the terminal portion. The location of the strain detection unit at can be freely selected. For example, by disposing the strain detection unit between the fatigue detection unit or the folded line unit and the terminal unit, the strain detection unit can be separated from the place where the stress concentration part of the structural material is the largest, Long-term reliability of the strain detector can be maintained.

Moreover, the fatigue degree detection strain gauge according to claim 3 of the present invention is the fatigue degree detection strain gauge according to claim 1,
The fatigue level detection unit is characterized in that a width at which the fatigue level detection unit is broken by a predetermined stress is increased stepwise.

  When the fatigue level detection strain gauge according to claim 3 has such a configuration, the fatigue level detection unit breaks in stages according to the level of fatigue of the structural material. Therefore, the progress of fatigue of the structural material can be detected in stages.

Moreover, the fatigue degree detection strain gauge according to claim 4 of the present invention is the fatigue degree detection strain gauge according to claim 1,
The corner formed by the edge of the folded tab of the folded line section and the edge of the fatigue detection section or the corner formed by the edge of the bypass section and the edge of the fatigue detection section Among them, at least one of the corners has an R shape with each edge as a tangent, and the R shape is formed to increase stepwise for each fatigue level detection unit.

  Since the fatigue level detection strain gauge according to claim 4 has such a configuration, the starting point of the fracture of the fatigue level detection unit due to fatigue of the structural material exists at the connection between the fatigue level detection strain gauge and the folded line unit. Unlike the fatigue detection strain gauge according to claim 1, the fatigue detection strain gauge is present in the connecting portion between the fatigue detection portion and the bypass portion, and therefore more easily broken than the fatigue detection strain gauge according to claim 1. It has a configuration. Therefore, the fatigue failure of the structural material can be predicted more quickly. Further, the fatigue level detection unit breaks in stages according to the fatigue level of the structural material. Therefore, the progress of fatigue of the structural material can be detected in stages.

  In particular, the curvature of the R shape of the corner of the space surrounded by the folded tab, the fatigue detection unit, the adjacent fatigue detection unit, and the bypass unit can be changed stepwise without changing the width of the fatigue detection unit. As the fatigue level of the structural material increases, fracture starts at the corner where the curvature is large, and the fatigue level is detected from each corner sequentially according to the progress of fatigue of the structural material. The part can be broken.

  The corner formed by the edge of the folded tab of the folded line section and the edge of the fatigue detection section or the corner formed by the edge of the bypass section and the edge of the fatigue detection section 2. At least one of the corners has an R shape with each edge as a tangent, and the R shape is formed to increase stepwise for each fatigue level detection unit. Fatigue level detection strain gauge described in 1.

Moreover, the fatigue degree detection strain gauge according to claim 5 of the present invention is the fatigue degree detection strain gauge according to claim 1,
The bypass part is formed so that the width of the bypass part located corresponding to each fatigue degree detection part is increased stepwise, and the bypass part is broken by a predetermined stress instead of the fatigue degree detection part. The fatigue degree detection strain gauge is attached from the rupture degree of the bypass part instead of detecting the fatigue degree of the structural material to which the fatigue degree detection strain gauge is attached from the rupture degree of the fatigue degree detection part. It is characterized by detecting the degree of fatigue of structural materials.

  The fatigue detection strain gauge according to claim 5 has such a configuration, so that the stress applied in the torsional direction of the structural material and the direction in which the fatigue detection strain gauge according to claim 1 measures the fatigue are different. It is possible to predict fatigue failure of a structural material due to stress concentration such as tensile stress applied in the direction. Further, the fatigue level detection unit breaks in stages according to the fatigue level of the structural material. Therefore, the progress of fatigue of the structural material can be detected in stages.

  ADVANTAGE OF THE INVENTION According to this invention, while being able to measure the distortion | strain of a structural material, the fatigue degree detection strain gauge which can predict the sign of the fatigue fracture which arises locally in a structural material in advance and exactly can be provided.

It is a top view which shows the fatigue degree detection strain gauge which concerns on the 1st Embodiment of this invention. It is a top view which expands and shows the folding tab and bypass for fatigue degree detection of the fatigue degree detection strain gauge shown in FIG. 1, and the fatigue degree detection part connected between both. It is a perspective view which shows roughly the state which attached the fatigue degree detection strain gauge which concerns on 1st Embodiment to the structural material. FIG. 4 is a first modified example of the fatigue level detection strain gauge according to the first embodiment, and is an enlarged plan view showing the fatigue level detection unit (FIG. 4A) and fatigue level detection shown in FIG. It is a circuit diagram (Drawing 4 (b)) corresponding to a strain gauge. The top view which expands and shows the fatigue degree detection part of the 2nd modification of the fatigue degree detection strain gauge concerning a 1st embodiment (Drawing 5 (a), and the fatigue degree detection part of the 3rd modification) FIG. 6 is a plan view (FIG. 5B). It is a top view which expands and shows the fatigue degree detection part of the 4th modification of the fatigue degree detection strain gauge which concerns on 1st Embodiment. It is a top view which expands and shows the fatigue detection part of the 5th modification of the fatigue detection strain gauge which concerns on 1st Embodiment. It is a top view which shows the fatigue degree detection strain gauge which concerns on the 2nd Embodiment of this invention in a partial block. It is a top view which shows the fatigue degree detection strain gauge relevant to this invention.

  The fatigue degree detection strain gauge according to the present embodiment is a fatigue degree detection strain gauge capable of appropriately performing the fatigue degree of a structure by detecting an electrical change in the resistance value of the resistor. This strain detection strain gauge has a strain detection unit in which a strand and an adjacent strand are arranged in parallel and connected via a folded tab, and a strand and an adjacent strand are arranged in parallel and connected through a folded tab. The folded line section connected in series with the strain detecting section, the folded line section, and the strain detecting section form a separate path, and one end thereof is connected to one terminal section of the terminal section via the folded tab of the folded line section and the strain detecting section. And the other end of the terminal portion is connected to the other terminal portion, and the fatigue detection portion is connected to the folded tab of the folded line portion. And each folded tab arranged in parallel is connected to the bypass part through the fatigue degree detection part, and the fatigue degree of the structural material to which the fatigue degree detection strain gauge is attached from the degree of fracture of the fatigue degree detection part Is supposed to be detected.

  Hereinafter, a fatigue level detection strain gauge according to a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a plan view showing a fatigue level detecting strain gauge according to the first embodiment of the present invention. FIG. 2 is an enlarged plan view showing a fatigue tab of the fatigue detection strain gauge shown in FIG. 1 and a bypass tab for detecting the fatigue and a fatigue detection unit connected between them. In the following description, the vertical direction of the film-like member in FIG. 1 is the longitudinal direction, and the horizontal direction is the width direction. Moreover, let the upper side of the film-like member in FIG. 1 be a front end side, and let the lower side be a base end side.

  The fatigue detection strain gauge 100 according to the present embodiment is used to detect strain and fatigue of general structural materials such as beams and columns of buildings, piers, steel towers, bridges, etc., and has flexible insulation. It comprises a film-like member 110 made of a body resin material, an electric resistor made of a metal foil patterned on the film-like member 110, a terminal part 120 connected to the end of the electric resistor, and the like. The electrical resistor includes terminal portions 121 and 122 (120), a strain detection portion 130, a folded line portion 140, a fatigue level detection portion 150, and a bypass portion 160.

  The film-like member 110 is made of a resin member, has flexibility, and has a rectangular shape.

  The terminal part 120 (121, 122) is one terminal part 121 formed on the base end side of the film-like member 110 and near the end part on one side in the width direction (left side in FIG. 1) and the other side ( It consists of the other terminal portion 122 formed in the vicinity of the end portion on the right side in FIG. An electric wire (not shown) is soldered to the terminal portion 120, and a change in the resistance value of the electric resistor composed of the strain detecting portion 130, the folded line portion 140, the fatigue degree detecting portion 150, and the bypass portion 160 is output to the outside. The strain and fatigue level of the structural material to which the fatigue level detection strain gauge 100 is affixed are detected by a calculation control means (not shown).

  The strain detection unit 130 is a width from the vicinity of the end of one side in the width direction of the film-like member 110 (left side in FIG. 1) to the vicinity of the center of the film-like member 110 in the width direction, and the tip of the film-like member 110 It is formed in a region extending from the vicinity to the vicinity of one terminal portion 121.

  In the present embodiment, the strain detection unit 130 has a thin metal foil with a constant length and is folded back in the same direction many times on the end side, and each extension portion with the constant length is slightly spaced. They are so-called zigzag folded shapes (hereinafter simply referred to as “zigzag folded” shapes) arranged in parallel with each other. In addition, each extending part of the strain detection unit 130 extends in the longitudinal direction of the film-like member 110.

  In addition, one end of the strain detection unit 130 is connected to one terminal unit 121, and the other end is connected to the folded line unit 140.

  More specifically, the strain detection unit 130 includes a plurality of strands (gauge sensing units) 131 (the above-described extension portion) and a folding tab 132 (the above-described folding unit), and the strain detection unit 130 has a tensile strain. As a result, the resistance value of the strain detector 130 increases and the resistance value of the entire electrical resistor increases. In addition, the shape of the inner part of the folding tab 132 in the portion where the folding tab 132 and the strand 131 of the strain detection unit 130 are connected has a curved shape in which the curvature gradually and continuously breaks due to fatigue. It has a difficult shape.

  The folded line portion 140 is a width from the vicinity of the other end (right side in FIG. 1) in the width direction of the film-like member 110 to the vicinity of the center in the width direction of the film-like member 110, and in the vicinity of the front end portion of the film-like member 110. To the other terminal portion 122.

  The folded line portion 140 has the same configuration as that of the strain detecting portion 130, and a metal foil having a narrow line width forms a zigzag shape. Then, one end tip side (the left end tip side in FIG. 1) of the folded line portion 140 is connected to the bypass part 160 via the fatigue degree detection unit 150, and the other end tip side (in FIG. 1). The front end side in the width direction right end portion) is connected to the terminal portion 122 and the bypass portion 160. Further, one end base end side (the left end base end side in FIG. 1) of the folded line portion 140 is connected to one end of the strain detection unit 130.

  More specifically, the folded line portion 140 includes a plurality of strands 141 and folded tabs 142, and the strands 141 extend in the longitudinal direction of the film-like member 110. Further, the shape of the inner portion of the folded tab 142 in the portion where the folded tab 142 and the strand 141 of the folded line portion 140 are connected has a curved shape in which the curvature gradually changes continuously, and fracture due to fatigue occurs. It has a difficult shape. As a result, when the fatigue detection unit 150 is all broken, no current flows through the bypass unit 160, and only a current flows through the folded line unit 140, so that the resistance value of the entire electrical resistor increases. It has become.

  As shown in FIG. 2, the fatigue level detection unit 150 is formed to extend from the tip of each folded tab 142 on the tip side of the folded line portion 140. In addition, one side edge part 150m of each fatigue degree detection part 150 (right side in FIG. 2) is continuously linear with one side edge part 140m (right side in FIG. 2) of the corresponding folded line part 140. I am doing. In the present embodiment, the fatigue level detection unit 150 is made of a metal foil having a thin line width, and is composed of an extended portion having a short length formed along the longitudinal direction. In the case of this embodiment, the fatigue level detection units 150 all have the same width, each extends along the longitudinal direction of the film-like member 110, and its proximal end is folded as described above. In addition to being connected to the folded tab 142 on the distal end side of the line portion 140, each distal end end portion is connected to a bypass portion 160 described later.

  The bypass portion 160 extends further in the width direction of the film member 110 so as to pass through a position that is further on the distal end side than the folded line portion 140 and spaced apart from each folded tab 142 on the distal end side of the folded line portion 140 by an equal distance. Yes.

  The bypass portion 160 is made of a metal foil having a thin line width, and one end in the width direction (left side in the drawing) is one end in the width direction of the folded line portion 140 via the fatigue detection portion 150 (the leftmost fatigue level in FIG. 2). The other end side (the right side in the figure) is connected to the rightmost folded line part 140 and the terminal part 122 in FIG. Each folded line section 140 is connected to the bypass section 160 via each fatigue level detecting section 150 at each folded tab 142. The electrical resistance of the bypass section itself is extremely low, and even if the bypass section 160 is distorted, the resistance value of the bypass section 160 does not change, and the resistance value of the electrical resistor as a whole does not change. Yes.

  In the present embodiment, the fatigue level detection strain gauge 100 is attached to the structural material via an adhesive or the like so that the fatigue level detection unit 150 is located at or near the stress concentration portion that occurs locally in the structural material. ing. When all the fatigue level detection units 150 and the folded tabs 142 of the folded line unit 140 are broken, no current flows through the bypass unit 160 and only a current flows through the folded line unit 140. As a result, the resistance value of the entire electrical resistor is increased at a stretch, and it is possible to quickly and accurately predict local fatigue failure of the structural material.

  At this time, even if a part of the fatigue level detection unit 150 is broken, the resistance value of the entire electrical resistor changes as it is. Therefore, the degree of fatigue of the structural material is determined based on the change of the resistor. It may be possible to detect a slight progress.

  The fatigue level detection strain gauge 100 according to the present embodiment is an electrical resistance type fatigue level detection strain gauge that can detect the fatigue level by using the fatigue level detection unit 150, but has the structure described above. It is not only specialized in detecting the fatigue level of the material, but when the strain is detected in the strain detector 130, the resistance value of the strain detector 130 changes, and the strain of the structural material can be detected from the changed value. It is possible.

  Then, the specific usage method of the fatigue degree detection strain gauge 100 mentioned above is demonstrated. FIG. 3 is a perspective view schematically showing a state in which the fatigue detection strain gauge according to the first embodiment is attached to a structural material. In FIG. 3, two fatigue degree detection strain gauges 100 </ b> A and 100 </ b> B are affixed to a connecting portion between a column 11 and a beam 12 as a general structural material.

  Since the two strain level detecting strain gauges 100A and 100B are attached to the column 11 and the beam 12 in this way, a bending load or a tensile load acts on the column 11 or the beam 12 of the structural material, and the degree of fatigue is previously determined. When the assumed fatigue level is reached, at least any one or all of the fatigue level detection units 150 including the fatigue level detection unit 150 located closest to the strain detection unit 130 (that is, the leftmost side in FIG. 1) The connection portion with the folded line portion 140 is broken. Then, by measuring the resistance value of the electrical resistor, it can be understood that the fatigue of the structural material has reached a prescribed fatigue level, which can be used for prediction of fatigue failure of the structural material.

  Since the fatigue level detection strain gauge 100 according to the present embodiment described above has both the fatigue level detection unit 150 and the strain detection unit 130, the following usage methods specific to the present invention are possible. Specifically, for example, when the fatigue level detection strain gauge 100 according to the present embodiment is provided in a general structural material of a pier that passes a lot of vehicles, for a while from the completion of the pier, the strain detection unit 130 detects the structural material. The trend of the degree of strain can be collected, and the tendency of the degree of strain accompanying the vehicle traffic of the structural material constituting the pier can be detected.

  Since the fatigue level detection strain gauge according to the present embodiment has such a configuration, the fatigue level detection unit 150 can be disposed at a place where stress concentration locally occurs in the structural material, and the fatigue level can be quickly and accurately determined. Can be detected. In particular, since the folded tabs 142 arranged in parallel are connected to the bypass unit 160 via the fatigue level detecting unit 150, the fatigue level detecting units 150 are respectively connected to the end portions of the folded tabs 142 arranged in parallel. The bypass part 160 can be extended in parallel to the film-like member leading edge. As a result, the fatigue level detection unit 150 can be disposed as close as possible to the distal end side of the film-like member 110, so that the progress of fatigue of the structural material can be detected more accurately.

  Further, as a related application of the present application shown in FIG. 9, the structure of the fatigue degree detection unit is generally a structure in which adjacent strands are connected by folded tabs 952, and in this case, the length of the folded tabs 952. L will have a certain length. On the other hand, in the case of the present embodiment, as is apparent from the above-described configuration, the folding tab is not provided in the fatigue level detection unit. Therefore, it is possible to bring the fatigue level detection unit 150 closer to the stress concentration unit in the case of the present embodiment than when the fatigue level detection unit 952 of the related application is arranged on the stress concentration unit side.

  In addition, since the fatigue level detection unit 150 is not formed on the terminal side, even if the fatigue level detection unit 150 is disposed at a place where stress concentration occurs locally, for example, solder bonding of the terminal unit 120 is performed along with the stress concentration. It is possible to prevent the stress from being generated in the portion, and it does not adversely affect the fatigue detection strain gauge itself.

  In addition, the usage method of the fatigue | exhaustion degree detection strain gauge like the above-mentioned embodiment is not limited to the case where a general structural material is used for a bridge pier, For example, it applies to the general structural material which makes the framework of a multi-story building. Also good. Thereby, for a while immediately after the building is completed, the strain detection unit 130 detects the trend of the degree of distortion of the structural material, whereby the change in the degree of distortion of the structural material after the building is completed can be analyzed.

  In addition, when a fatigue failure of a structural material is predicted due to the breakage of the fatigue level detection unit 150, by collecting a trend of the degree of strain of the structural material from the strain detection unit 130 for a while immediately after that, by what phenomenon It is possible to grasp whether the fatigue failure of the structural material is approaching. On the other hand, even if the fatigue detection unit 150 does not break, for example, when a heavy object such as an industrial machine is installed on the upper floor of a building, the distortion of the structural material for a while immediately after the installation of the heavy object. By collecting the trend of the degree from the strain detection unit 130, it is possible to analyze the influence of the installation of heavy objects on the structural material.

  In addition, the arrangement | positioning position of a distortion | strain detection part is not limited to the above-mentioned embodiment, You may arrange | position to a film member base end side rather than a fatigue degree detection part, as shown in FIG. Thereby, the influence which a distortion | strain detection part receives by the fatigue of a structural material can be made small. This configuration will be described in detail later as a second embodiment.

  Next, various modifications of the fatigue level detection strain gauge will be described. These various modifications are obtained by partially deforming the shape of the fatigue level detection unit 150 in the first embodiment.

  Initially, the 1st modification of the fatigue detection part which concerns on embodiment mentioned above is demonstrated. In addition, about the structure equivalent to embodiment mentioned above, a corresponding code | symbol is attached | subjected and detailed description is abbreviate | omitted. FIG. 4A is a first modification of the fatigue level detection strain gauge according to the first embodiment, and is an enlarged plan view showing the fatigue level detection unit 250.

  For convenience of explanation, the folded line section 240 in FIG. 4A is referred to as a first folded line section 240A, a second folded line section 240B, and a third folded line section 240C from the left in the figure. The fatigue level detection unit 250 connected to each of them is referred to as a first fatigue level detection unit 250A, a second fatigue level detection unit 250B, and a third fatigue level detection unit 250C. 4A shows a part of the fatigue detection unit 250 arranged on the strain detection unit side, and the fatigue detection unit 250 corresponding to FIG. 1 is on the right side of FIG. 4A. Further formed.

  In the fatigue level detection unit 250 (250A, 250B, 250C,...) According to the first modification, the width of each fatigue level detection unit 250 is the other end side (right side in the figure) as shown in FIG. It is getting wider step by step. Specifically, the width W1 of the first fatigue level detector 250A located on the left side in the drawing is the narrowest, the width W2 of the second fatigue level detector 250B, and the width W3 of the third fatigue level detector 250C. It gets wider in order. As a result, as the fatigue level of the structural material increases, the fatigue level detection unit 250 and the folded line portion 240 are disconnected from each other in order of decreasing width of the fatigue level detection unit 250, and the resistance value of the electrical resistor increases stepwise. And by detecting the step change of this resistance value, it becomes possible to detect the progress of the fatigue of the structural member step by step.

  The above description will be described based on a circuit diagram. FIG. 4B is a circuit diagram corresponding to the fatigue level detection strain gauge shown in FIG. Here, the circuit diagram of FIG. 4B will be described in correspondence with the configuration shown in FIG.

  FIG. 4 shows the resistance of the right strand 241 in the first folded line portion 240A and the left strand 241 in the second folded line portion 240B connected to the first folded line portion 240A from the fatigue level detecting portions 250A to 250B in FIG. R1 in FIG. 4B, the right strand 241 in the second folded line portion 240B from the fatigue level detecting portion 250B to 250C in FIG. 4A and the left side in the third folded line portion 240C connected thereto. The resistance of the strand 241 is R2 in FIG. 4B, the third folded line portion from the fatigue level detection unit 250C in FIG. 4A to the fatigue level detection unit adjacent to the right side in the drawing not shown here. The right side strand 241 in 240C and the left side strand in the folded line portion adjacent to the right side in the drawing (not shown here) connected thereto. The de of the resistor and R3 in FIG. 4 (b). Further, the resistance in a state where the structural material is not fatigued and none of the fatigue level detection parts 250 is broken is Rh in FIG. 4B.

  Here, when the structural material is not fatigued, the current passes through the resistance Rh, the first fatigue level detection unit 250A, and the bypass unit 260. In addition, when the structural material reaches the first stage fatigue level and the connection portion between the first fatigue level detection unit 250A and the corresponding folded line portion 240A breaks, the current is the resistance Rh, R1, the second fatigue level. The resistance value of the electrical resistor increases by one step through the degree detector 250B and the bypass unit 260. Further, the fatigue of the structural material further progresses and the structural material reaches the second fatigue stage, and the first fatigue level detection unit 250A and the second fatigue level detection unit 250B and the corresponding folded line portions 240A and 240B In the case where each of the connecting portions is broken, the current passes through the resistances Rh, R1, R2, the third fatigue level detection unit 250C, and the bypass unit 260, and the resistance value of the electric resistor further increases by one level and reaches the second level. Reach. Further, the fatigue of the structural material further progresses and the structural material reaches the third fatigue stage, and the first fatigue level detection unit 250A, the second fatigue level detection unit 250B, and the third fatigue level detection unit 250C and these When all the connection parts of the folded line parts 240A, 240B, and 240C corresponding to rupture, the current passes through the resistances Rh, R1, R2, R3, and the bypass part 260, and the resistance value of the electric resistor further increases by one step. And reach the third stage. Thereafter, as the degree of fatigue increases, such a stepwise fracture phenomenon and a corresponding stepwise increase in the resistance value of the electric resistor occur. And by detecting such a step change in resistance value, the fatigue level of the structural material can be detected step by step.

  Next, a second modification of the fatigue level detection unit according to the above-described embodiment will be described. In addition, about the structure equivalent to the 1st modification mentioned above, a corresponding code | symbol is attached | subjected and detailed description is abbreviate | omitted. FIG. 5A is an enlarged plan view showing a fatigue level detection unit 350 of a second modification of the fatigue level detection strain gauge according to the first embodiment.

  The fatigue level detection unit 350 according to the second modification is surrounded by the front end side edge portion 342e of the folded tab 342, the fatigue level detection unit 350A (350B), the fatigue level detection unit 350B (350C), and the bypass unit 360, respectively. The corner portion of the space, which is the folded tab side corner portion, is characterized in that the R shape is formed in a stepwise manner. In the figures corresponding to the following description, the magnitude and the degree of change of R are exaggerated to facilitate understanding of the description.

  Specifically, the fatigue level detection unit 350 according to the second modification includes an edge portion 350m of each fatigue level detection unit 350 and a return tab 342 of the return line portion 340 corresponding thereto as shown in FIG. The radii of curvature of the connecting portions c1, c2, c3 with the leading end side edge portion 342e are gradually increased from zero. That is, the concave R shape of the connection portions c1, c2, and c3 increases stepwise toward one end side (the right side in FIG. 5A).

  As a result, as the fatigue level of the structural material increases, the concave R shapes in the connection portions c1, c2, and c3 of the fatigue level detection unit 350 and the folded line portion 340 are disconnected in ascending order, and the resistance value of the electric resistor is stepwise. To rise. And the fatigue degree of a structural material is detectable in steps by detecting this change in resistance in steps.

  Next, a third modification of the fatigue level detection unit according to the above-described embodiment will be described. In addition, about the structure equivalent to each modification mentioned above, a corresponding code | symbol is attached | subjected and detailed description is abbreviate | omitted. FIG. 5B is an enlarged plan view showing the fatigue level detection unit 450 of the third modification of the fatigue level detection strain gauge according to the first embodiment.

  As shown in FIG. 5B, the fatigue level detection unit 450 according to the third modification is connected to the center portion in the width direction of the folded line portion 440. And the corner | angular part of the space enclosed by the folding | turning tab 442 and the fatigue detection part 450A (450B) and the adjacent fatigue degree detection part 450B (450C) and the bypass part 460, and the folding tab side corner | angular part are R shape. Is characterized by being formed in a stepwise manner.

  Specifically, the radii of curvature of the connection portions d1, d2, d3 between the edge portion 450m of each fatigue level detection portion 450 and the tip side edge portion 442e of the return line portion 442 of the return line portion 440 corresponding to this are substantially 0. It is getting bigger gradually. That is, the concave R shape of the connecting portions d1, d2, and d3 increases stepwise toward one end side (the right side in FIG. 5B). As a result, as the fatigue level of the structural material increases, the concave R shapes in the connection portions d1, d2, and d3 of the fatigue level detection portion 450 and the folded line portion 440 are disconnected in ascending order, and the resistance value of the electric resistor is stepwise. To rise. And by detecting the step change of the resistance value, the fatigue level of the structural material can be detected step by step.

  In addition, since each fatigue degree detection part 450 is connected to the center part of the width direction of the return line part 440, the starting point of the fracture | rupture by fatigue is the edge part 450m of each fatigue degree detection part 450, and the return line corresponding to this Two portions are formed on both sides of the connecting portion of the portion 440 with the distal end side edge portion 442e of the folded tab 442, and the fatigue degree detecting portion 450 is easily broken. As a result, the fatigue of the structural material can be detected from the initial stage.

  Further, in this modified example, the fracture start point in the fatigue level detection unit 450 is larger (doubled) than in the second modified example, so that the fracture according to the fatigue level of the structural material is surely performed, This is reliably detected step by step according to the progress of fatigue of the structural material.

  Next, the 4th modification of the fatigue detection part which concerns on embodiment mentioned above is demonstrated. In addition, about the structure equivalent to each modification mentioned above, a corresponding code | symbol is attached | subjected and detailed description is abbreviate | omitted. FIG. 6 is an enlarged plan view showing a fatigue level detection unit 550 of a fourth modification of the fatigue level detection strain gauge according to the first embodiment.

  The fatigue level detection unit 550 according to the fourth modification is connected to the central portion in the width direction of the folded line portion 540 as shown in FIG. Similarly to the second and third modifications, the corner of the space surrounded by the folding tab 542, the fatigue detection unit 550A (550B), the adjacent fatigue detection unit 550B (550C), and the bypass unit 560. The portions e1, e2, e3, f1, f2, and f3 are characterized in that the R shape is increased stepwise.

  Specifically, the curvature radii of the corners e1, e2, and e3 between the edge portion 550m of each fatigue detection portion 550 and the corresponding end portion 542e of the return tab of the return line portion 540 and each fatigue detection are detected. The curvature radii of corners f1, f2, and f3 between the edge portion 550m of the portion 550 and the corresponding edge portion 560m of the bypass portion 560 are gradually increased from zero. That is, the concave R shape of the corners e1, e2, e3, f1, f2, and f3 is gradually increased toward one end side (right side in the figure). Therefore, each fatigue level detection unit 550 can form a total of four locations on the both sides of the connection portion between the fatigue level detection unit 550, the folded line portion 540, and the bypass portion 560, as the starting point of fracture due to fatigue. The detection unit 550 is easily broken. As a result, the fatigue of the structural material can be detected from the initial stage.

  Further, as the fatigue level of the structural material increases, the connection between the fatigue level detection unit 550 and the folded line portion 540 and the concave R shape at the connection level between the fatigue level detection unit 550 and the bypass unit 560 are disconnected in ascending order, The resistance value increases gradually. And by detecting the step change of the resistance value, the fatigue level of the structural material can be detected step by step.

  In addition, according to the present modification, the fracture start point is quadrupled compared to the second modification, and the fracture start point is doubled compared to the third modification, so that the fracture according to the fatigue level of the structural material is ensured. This is reliably detected step by step according to the progress of fatigue of the structural material.

  Next, a fifth modification of the fatigue detection unit according to the above-described embodiment will be described. In addition, about the structure equivalent to the various modifications mentioned above, a corresponding code | symbol is attached | subjected and detailed description is abbreviate | omitted. FIG. 7 is an enlarged plan view showing a fatigue level detection unit of a fifth modification of the fatigue level detection strain gauge according to the first embodiment.

  As shown in FIG. 7, the fatigue level detectors 650 (650A, 650B, 650C,...) According to the fifth modified example include the bypass units 660 positioned corresponding to the fatigue level detectors 650A, 650B, 650C. The width is gradually increased toward the other end side (right side in the figure). Specifically, the width H1 of the first bypass portion 660A located on the left side in the drawing is the narrowest, and the width H2 of the second bypass portion 660B and the width H3 of the third bypass portion 660C increase in this order. As a result, as the fatigue level of the structural material increases, the bypass portion 660 is disconnected in order of increasing width, and the resistance value of the electrical resistor increases stepwise. And by detecting the step change of this resistance value, it becomes possible to detect the progress of the fatigue of the structural member step by step.

  Subsequently, a fatigue level detection strain gauge according to a second embodiment of the present invention will be described with reference to the drawings. FIG. 8 is a plan view showing a fatigue degree detecting strain gauge 100 ′ according to the second embodiment of the present invention. In the following description, the longitudinal direction, the width direction, the distal end side, and the proximal end side are the same as those in the first embodiment.

  A fatigue detection strain gauge 100 ′ according to the present embodiment includes a film-like member 110 ′ made of an insulating resin material having flexibility, and an electric resistor made of a metal foil patterned on the film-like member 110 ′. The terminal portion 120 ′ is connected to the end of the electric resistor. The electrical resistor includes a strain detection unit 130 ′, a folded line unit 140 ′, a fatigue level detection unit 150 ′, and a bypass unit 160 ′.

  The film-like member 110 'is made of a resin member, has flexibility, and has a rectangular shape.

  The terminal portion 120 ′ is formed on the base end side of the film-like member 110 ′ and in the vicinity of both ends in the width direction. An electric wire (not shown) is soldered to the terminal portion 120 ′ to output a change in resistance value of the strain detecting portion 130 ′ to the outside, and the folded line portion 140 ′, the fatigue degree detecting portion 150 ′, and the bypass portion 160. The change in the resistance value of the electrical resistor composed of “is output to the outside, and the strain and fatigue level of the structural material to which the fatigue level detection strain gauge 100 ′ is attached are detected by a calculation control means (not shown).

  The strain detector 130 ′ is shown here in a block diagram, but its configuration is the same as that of the first embodiment. In the present embodiment, the strain detection unit 130 ′ and the folded line unit 140 ′ are arranged side by side in the longitudinal direction via the common terminal unit 120 ′.

  The folded line portion 140 ′ is on the other side in the width direction (right side in FIG. 8) of the film-like member 110 ′ from the vicinity of the end portion on the one side in the width direction (left side in FIG. 8) of the film-like member 110 ′. It is formed in a region extending from the vicinity of the tip portion of 110 ′ to the vicinity of the other terminal portion 122 ′.

  The folded line portion 140 'is formed in a folded shape with a thin metal foil. Then, one end front end side (the left end front end side in FIG. 8) of the folded line section 140 ′ is connected to the bypass section 160 ′ via the fatigue detection section 150 ′, and the other end front end side ( 8 is connected to the terminal portion 122 ′ and the bypass portion 160 ′. Further, one end portion base end side (the left end base end side in FIG. 8) of the folded line portion 140 'is connected to the terminal portion 121'. The strand 141 ′ of the folded line portion 140 ′ extends in the longitudinal direction of the film-like member 110 ′.

  More specifically, the folded line portion 140 'includes a plurality of strands 141' and a folded tab 142 '. In addition, the shape of the inner portion of the folded tab 142 ′ where the folded tab 142 ′ and the strand 141 ′ of the folded line portion are connected has a curved shape in which the curvature gradually and continuously breaks due to fatigue. The shape is difficult to occur. As a result, when all of the fatigue detection units 150 ′ are broken, current does not flow through the bypass unit 160 ′, but current flows only through the folded line unit 140 ′, and the resistance value of the entire electrical resistor is reduced. It is going to go up.

  As shown in FIG. 2 in the first embodiment, the fatigue level detection unit 150 ′ is formed at the tip of each folding tab 142 ′ on the tip side of the folding line portion. In the present embodiment, the fatigue level detection unit 150 ′ is made of a metal foil having a thin line width, and is formed of an extended portion having a short length formed along the longitudinal direction. In the case of the present embodiment, the fatigue level detection parts 150 ′ all have the same width, each extends along the longitudinal direction of the film-like member 110 ′, and the proximal end part thereof has been described above. While connecting with the return | turnback tab 142 'at the front end side of street return track | line part 140', each front end side edge part is connected to bypass part 160 'mentioned later, respectively. Note that one side edge (right side in FIG. 8) of each fatigue level detection unit 150 ′ is stepped (width) at the joint with one side edge (right side in FIG. 8) of each folded line portion 140 ′. It is connected in a straight line without any deviation in direction. Further, when the fatigue level detection unit 150 ′ breaks, all the fatigue level detection units 150 ′ are broken at a time, and it is reliably detected that the degree of fatigue of the structural material is increased. Note that it may be detected that the fatigue of the structural material has started to progress by detecting that a part of the fatigue degree detection unit 150 'is broken from a change in the resistance value of the electric resistor.

  The bypass portion 160 ′ extends further in the width direction of the film member 110 ′ so as to pass through a position further away from each of the folded tabs 142 ′ of the folded line portion 140 ′ by an equal distance further from the folded line portion 140 ′. Exist. The bypass portion 160 ′ is made of a thin metal foil, one end in the width direction (left side in the figure) is connected to one end in the width direction of the folded line portion 140 ′, and the other end side (right side in the figure) is a terminal. Connected to the section 122 '. Further, each folded tab 142 ′ of the folded line section 140 ′ is connected to the bypass section 160 ′ via the corresponding fatigue level detecting section 150 ′. The electrical resistance of the bypass part itself is extremely low, and even if the bypass part 160 ′ is distorted, the resistance value of the bypass part 160 ′ does not change and the resistance value of the electrical resistor as a whole does not change. It has become.

  And also in this embodiment, while detecting the distortion | strain of a structural material by the change of the resistance value of the distortion | strain detection part 130 'with the common terminal part 120', the return | turnback track | line part 140 ', the fatigue degree detection part 150', and a bypass part The degree of fatigue of the structural material is detected from the change in the resistance value of the electric resistor 160 ′.

  Even with such a configuration, an action equivalent to that of the first embodiment can be exhibited. That is, the fatigue level detection unit can be arranged at a location where stress concentration locally occurs in the structural material, and the fatigue level can be detected quickly and accurately. Furthermore, the strain of the structural material can be detected, and the fatigue level of the structural material can be detected to predict the fatigue level.

  Further, in the fatigue detection strain gauge 100 ′ according to the second embodiment, one end of the bypass portion 160 ′ is connected to one terminal portion 121 ′ via the folded tab 142 ′ of the folded line portion 140 ′. The location of the strain detector 130 'on the film member can be freely selected. Since both ends of the strain detector 130 ′ can be directly connected to the terminal portion 120 ′, the degree of freedom of the layout of the strain detector on the film-like member can be improved, and the strain detector 130 ′ can be used as a fatigue detector. 150 'or the folded line portion 140' and the terminal portion 120 '. As a result, the strain detector 130 ′ can be separated from the place where the stress concentration portion of the structural material is the largest, and the long-term reliability of the strain detector 130 ′ can be maintained.

  The arrangement pattern of the metal foil according to the embodiment and each modification described above is merely an example, and it goes without saying that various modifications can be applied without departing from the present invention.

  In addition, when the fatigue detection unit 150 (150 ′) is broken in the first and second embodiments, the fatigue detection unit 150 (150 ′) located on the leftmost side in FIGS. 1 and 8 is surely broken. For this purpose, it is preferable that the fatigue degree detection unit 150 (150 ′) is appropriately cut so that the width of the fatigue degree detection unit is narrowed.

  Further, the film-like member of the fatigue level detection strain gauge may not necessarily be made of resin and has flexibility as long as the strain detection unit and the fatigue level detection unit formed thereon play a role. It does not have to be.

  In addition, as an application example of the fatigue detection strain gauge according to the above-described embodiment and its modifications, a general structural material composed of columns and beams has been introduced, but the application target is limited to such a thing. Instead, for example, the present invention can be applied to a portion where stress concentration is likely to occur locally, such as a welded portion of a general structural material or a portion where the shape changes abruptly (the shape factor changes abruptly). Similarly, the above-described embodiment and its modifications are included in parts where stress concentration is likely to occur locally, such as a welded part or a part whose shape changes suddenly even if it is a mechanical structural material having the same mechanical properties as a strain gauge. The fatigue degree detection strain gauge according to the present invention can be applied.

100 (100A, 100B), 100 ′ Fatigue degree detection strain gauge 110, 110 ′ Film-like member 121, 122 (120), 121 ′, 122 ′ (120 ′) Terminal portion 130, 130 ′ Strain detection portion 140, 140 ′ Folded line part 141, 141 ′ Strand 142, 142 ′ Folded tab 150, 150 ′ Fatigue degree detecting part 160, 160 ′ Bypass part 240 Folded line part 250 Fatigue degree detecting part 260 Bypass part 340 Folded line part 350 Fatigue degree detecting part 360 Bypass section 440 Folded line section 450 Fatigue level detection section 460 Bypass section 540 Folded line section 550 Fatigue level detection section 560 Bypass section 640 Folded line section 650 Fatigue level detection section 660 Bypass section

Claims (5)

A fatigue degree detection strain gauge capable of appropriately performing the fatigue degree of a structure by detecting an electrical change in the resistance value of a resistor,
A strain detecting unit in which the strand and the adjacent strand are arranged in parallel and connected via a folded tab;
A strand and an adjacent strand are arranged in parallel and connected via a folded tab, and a folded line portion connected in series with the strain detector,
The return line part and the strain detection part form a separate path, and one end is connected to one terminal part of the terminal part via a return tab and a strain detection part of the return line part, and the other end is the other end of the terminal part. A bypass section connected to the terminal section of
A fatigue degree detection unit connected to each folded tab arranged in parallel to the folded line portion;
Each folded tab arranged in parallel is connected to the bypass part via the fatigue detection part,
A fatigue level detection strain gauge, wherein the fatigue level of a structural material to which the fatigue level detection strain gauge is attached is detected from the degree of breakage of the fatigue level detection unit.   Instead of connecting one end of the bypass part to one terminal part of the terminal part via the return tab of the return line part and the strain detection part, one end of the bypass part is connected via the return tab of the return line part. 2. The fatigue degree detecting strain gauge according to claim 1, wherein the strain detecting part is connected to one terminal part, and the strain detecting part is arranged side by side in the longitudinal direction via the folded line part and the terminal part.   2. The fatigue degree detection strain gauge according to claim 1, wherein the fatigue degree detection unit is formed so that a width at which the fatigue detection part is broken by a predetermined stress is increased stepwise. 3.   The corner formed by the edge of the folded tab of the folded line section and the edge of the fatigue detection section or the corner formed by the edge of the bypass section and the edge of the fatigue detection section 2. At least one of the corners has an R shape with each edge as a tangent, and the R shape is formed to increase stepwise for each fatigue level detection unit. Fatigue level detection strain gauge described in 1. The bypass part is formed so that the width of the bypass part corresponding to each fatigue level detection part is increased stepwise, and the bypass part is broken by a predetermined stress instead of the fatigue level detection part. Instead of detecting the fatigue level of the structural material to which the fatigue level detection strain gauge is pasted from the degree of fracture of the fatigue level detection unit, the structure in which the fatigue level detection strain gauge is pasted from the level of fracture of the bypass unit The fatigue degree detection strain gauge according to claim 1, wherein the fatigue degree of the material is detected.

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