JP2000065705A - Resin impregnated strand testing apparatus and method using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make efficiently and highly accurately performable a tensile test and a fatigue test by windening a part of the width of a groove for fixing a test piece. SOLUTION: The width of the groove 6 for fixing a strand test piece provided to a gripper has a part widened in a tension applying direction. That is, the width 51 of the groove is made wider than the width 52 thereof. Further, the shape of the end part of the test piece is molded so as to become wider than the diameter of the original test piece. Furthermore, a thermostatic tank heating only the measuring part of the test piece substantially is provided. By this constitution, the viscoelasticity of a resin impregnated strand can be measured highly accurately and efficiently not only under a room temperature condition but also under a raised temp. condition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus and a method for testing a resin-impregnated strand. More specifically, the present invention relates to a tensile test device or a fatigue test device for a resin-impregnated strand.

[0002]

2. Description of the Related Art In recent years, lightweight and high-strength fiber-reinforced plastics (hereinafter, referred to as FRP) have been widely used as structural materials for various structures and machines.
However, considering the environment in which machines and structures using the FRP are placed, when designing such machines and structures, the mechanical properties of the FRP, such as the viscoelastic behavior, It is important to understand the time dependence or temperature dependence of the data.

In order to grasp these characteristics, the F
Generally, a strand of RP is manufactured and its mechanical properties are evaluated by a tensile tester or the like.

As a specific method for determining the tensile strength of a strand impregnated with such a resin, for example, JI
As stipulated in SR7601 (Carbon Fiber Test Method), a test piece of a fixed length is cut out from a resin-impregnated strand, and both ends are gripped with a gripper to reinforce the test piece. Is measured.

[0005] This gripper is, for example, as shown in FIG. 1 and comprises a plate 1 having a groove corresponding to the diameter of a strand 4 and two plates 2 and 3 sandwiching the plate. In the test, as shown in FIG. 2, the test is performed by bonding both ends of the strand 4 so as to be sandwiched by three members, and applying a load to the strand through the hole 5.

However, according to this method, the contact area between the gripper and the test piece cannot be made sufficiently large as compared with the cross-sectional area of the test piece. Even if the test was not performed or the sample did not fall off, the test piece slipped at the grip, and a very low reliability measurement result was sometimes obtained.

Further, when a method as described in JIS R7601 is applied to a creep test or a fatigue test under a high temperature, and the entire tensile test apparatus is subjected to a temperature rise condition,
Since the temperature of the gripper rises and the adhesive effect of the adhesive decreases, and the strands easily come off from the gripper due to vibration, the reliability of the test becomes extremely low, making the test virtually impossible. Was.

Further, conventionally, a ring-shaped test piece was used,
A method of determining the tensile strength in the week direction by expanding the inner diameter of the test piece with a half-disc has also been adopted, but this method does not cause the above problem due to the absence of the gripper. There was an essential problem that a bending stress was applied at the corner portion and an accurate tensile test could not be performed.

[0009]

In view of the above problems, there has been a demand for an apparatus capable of efficiently and accurately performing a tensile test or a fatigue test of a resin-impregnated strand. Further, there has been a demand for a device capable of performing a creep test or a fatigue test under a temperature rising condition efficiently and with high accuracy.

[0010]

[Summary of the Invention] <Summary> A first tensile tester of the present invention is for measuring viscoelasticity by applying tension to a strand test piece impregnated with a resin. And a grip for reinforcing both ends of the strand test piece, and the width of the groove for fixing the strand test piece provided in the grip is widened in the direction of applying tension. Having a portion that is formed.

The second tensile test apparatus of the present invention is for measuring the viscoelasticity by applying a tension to the strand test piece under the condition of elevated temperature, and substantially measures the measured portion of the strand test piece. Characterized in that it is provided with a constant temperature bath capable of heating only the water.

The first method for measuring the viscoelasticity of a resin-impregnated strand of the present invention is to measure the viscoelasticity by applying tension to a resin-impregnated strand test piece, and it comprises the following steps. It is a feature. (1) a step of forming the end of the strand test piece wider than the diameter of the original strand test piece; and (2) a direction in which tension is applied to a gripper for fixing the end of the strand test piece. (3) a step of providing a groove having a portion whose width increases toward (3), and (3) a step of fixing the strand test piece obtained in the step (1) so as to be fitted to the gripper obtained in the step (2). (4) a step of measuring the viscoelasticity by applying tension to the strand test piece whose end is fixed in the step (3).

The second method for measuring the viscoelasticity of a resin-impregnated strand according to the present invention is to measure the viscoelasticity of a resin-impregnated strand by heating substantially only the portion to be measured using a tensile tester. It is a feature.

<Effect> According to the present invention, the viscoelasticity of a resin-impregnated strand can be measured with high accuracy and high efficiency. Further, according to the present invention, the viscoelasticity of the resin-impregnated strand can be measured with high accuracy and high efficiency not only at room temperature but also at elevated temperature.

[Specific Description of the Invention] <First Tensile Test Apparatus and Measuring Method of Viscoelasticity> The first apparatus and measuring method of the present invention are characterized by a gripper and a strand test piece. Except for the gripper and the strand test piece, the same one as a conventionally used tensile tester can be used, and the same method as the conventional measurement method can be used.

The tensile tester which can be used is not particularly limited, but includes a constant speed moving type, a constant weight type, a constant speed elongation type,
And others. Generally, JIS L7
02, a test apparatus that satisfies the conditions specified by ASTM (D-76) or the like is used.

The first tensile tester and the method for measuring viscoelasticity of the present invention are characterized by a grip which reinforces the end of the resin-impregnated strand to be tested.

An example of the structure of a general grip is as shown in FIG. The gripper is made of plate materials 1, 2 and 3, and the plate material 1 has grooves 6 for fixing the strands 4.
Is provided. The end of the strand test piece 4 is incorporated into the groove 6 and is sandwiched between the plates 2 and 3. Generally, these members are bonded by an adhesive or the like.

The strand whose end is reinforced by the gripper is incorporated in the tensile test apparatus as described above, and is shown in FIG.
The tension is applied through the hole 5 as shown in FIG.

Here, in the conventional tensile test apparatus,
The plate 1 constituting the gripper was as shown in FIG. The provided groove 6 has a uniform width, and the width 41 and the width 42 are substantially the same.

On the other hand, in the tensile test apparatus and the viscoelasticity measuring method of the present invention, the width of the groove 6 for fixing the strand test piece provided on the gripper increases in the direction in which the tension is applied. It has a part that is. This example is shown in FIGS. 5 (a) and 5 (b). When incorporated in a tensile tester, tension is applied in the direction of the arrow. In the present invention, the width of the groove 6 is not uniform, and (width 51)> (width 52). The width of the groove and the length 53 of the groove are appropriately determined according to the shape of the strand test piece to be measured, for example, the length of the groove is 55 mm, the width of the groove is 3 mm in a wide portion, 2 mm in the narrow part.

In the first viscoelasticity measuring method of the present invention, the shape of the end of the strand test piece is formed wider than the diameter of the original strand test piece.

First, the strand test piece is, for example, JIS
It is created by a method specified in R7601. Subsequently, it is shaped into a shape adapted to the method of the invention. The molding of the strand specimen should be done so as not to damage the fibers contained in the strand specimen,
For example, it is preferable that the end portion of the strand test piece is heated to a temperature higher than the softening point of the resin and then rolled. It should be noted that molding by cutting or the like may cut fibers contained in the strand, and when such a strand test piece is used, an accurate measurement value may not be obtained.

The shape after molding is the groove 6 of the gripper described above.
It can be fitted to. A specific example of the shape of the end of the strand test piece is as shown in FIG.
FIGS. 3A to 3C show, for example, the shapes when the end portions of the strand test pieces are molded. 3A is a top view of the strand test piece, FIG. 3B is a side view, and FIG. 3C is a front view. The original diameter 32 of the strand test piece is smaller than the narrow portion 52 of the groove of the gripper, and the width of the wide portion 31 of the strand test piece is wider than the narrow portion 52 of the groove of the gripper. 51 or less. When the strand test piece has such a shape with respect to the groove of the gripper, the effect of the present invention is exerted.

The shapes of the strand test pieces in the method of the present invention are shown in FIGS. 3 (d) to 3 (f) in addition to FIGS. 3 (a) to 3 (c).
It may be. The dimensions at this time are as shown in FIG.
This is the same as the case (c).

<Second Tensile Test Apparatus and Measuring Method of Viscoelasticity> The second apparatus and measuring method of the present invention are used for measuring the viscoelasticity of a strand test piece under a condition of elevated temperature.
Except for the means for heating the strand test piece, this apparatus and the measuring method use the same as the conventionally used tensile test apparatus, and the same method as the conventional measuring method can be used. . Specific devices are those described in the section of the first tensile tester and the method of measuring viscoelasticity.

In the second measuring method of the present invention, substantially only the measured portion of the strand test piece is heated.
Here, the part to be measured is, for example, a part that is not held by a gripper or the like and that is composed of only strands.
Specifically, it refers to a portion 21 in FIG. 2 or a part thereof.

Means for heating only the portion to be measured of the strand test piece is optional, and examples thereof include a method of putting only the portion to be measured into a constant temperature bath, a method of blowing hot air only to the strand test piece, and others. Of these, the method of putting the part to be measured in a constant temperature bath is preferable in terms of the accuracy of temperature control and the like. In addition, heating substantially only the measured portion of the strand test piece means that the target to be directly heated is the strand test piece. Is excluded from being heated.

The second measuring device of the present invention comprises a constant temperature bath for heating substantially only the measuring portion of the strand test piece. A schematic diagram of such an apparatus is as shown in FIG. In the apparatus of FIG. 6, the strand test piece 4 penetrates the thermostatic bath 6 and is held by the grip 7 outside the thermostatic bath 61. The opening for penetrating the strand test piece provided in the constant temperature bath 61 is preferably large enough not to contact the strand test piece,
It is preferred that it not be unnecessarily large. If the opening is too large, it becomes difficult to control the temperature of the thermostatic oven, or parts other than the strand test piece, such as the gripper 7, may be heated. Care must be taken because the openings may come into contact and an accurate measurement may not be obtained.

A fluid, generally a gas such as air, flows inside the constant temperature bath 61, and the temperature inside the constant temperature bath is kept constant. The temperature is determined according to the measurement conditions,
Generally, the temperature is from room temperature to 300 ° C. In the constant temperature bath, a stirring blade or the like may be provided as necessary in order to make the temperature distribution uniform.

It is preferable that the second apparatus and the measuring method of the present invention be combined with the first apparatus and the measuring method of the present invention. With this combination, it is possible to perform the measurement under the elevated temperature condition with higher accuracy and higher efficiency.

[0032]

EXAMPLE 1 Aramid fiber Kevlar 49 (Toray Co., Ltd.) was used as a test piece.
An AFRP strand in which an epoxy resin Forca (manufactured by Tonen) was combined with a fiber bundle manufactured by DuPont and Technora (manufactured by Teijin) was used. Specifically, the fiber bundle is impregnated with an epoxy resin using a resin impregnating device, wound on a winding frame, and subjected to primary curing at 120 ° C. for 1 hour, and then to secondary curing at 120 ° C. for 1 hour. To produce an AFRP strand. 31 this strand
The required number of pieces were cut at a length of 0 mm.

A part of the cut strand was used as a sample for comparison, and both ends were fixed using a grip having a groove as shown in FIG. 4 and a tensile test was performed.

The remaining strands are heated until both ends are heated to a temperature higher than the softening point of the resin, and are rolled by applying pressure in a direction perpendicular to the length direction of the strands.
It was formed into a fan shape as shown in (a) to (c). Both ends of the strand were fixed using a grip having a groove as shown in FIG. 5A, and a tensile test was performed.

When the tensile test is carried out at a temperature higher than room temperature, when the measurement is carried out by the method of the present invention, the test is carried out using only a strand as shown in FIG. In the comparative example, the test was performed on the entire tensile tester under the condition of elevated temperature. Table 1 shows the obtained results.
Was as shown in FIG.

Table 1 Results of Static Tensile Test Strand Gripping Device Load Speed Test Results End Shape Groove Shape Temperature (mm / min) (Number of Successful Evaluations / Number of Trials) (Invention) Sector Forming FIG. 5 (a) Room temperature 100 10 / 10 ◎ Fan-forming type Fig. 5 (a) Room temperature 1 10/10 ◎ Fan-forming type Fig. 5 (a) Room temperature 0.01 10/10 ◎ Fan-forming type Fig. 5 (a) 130 ℃ 100 10/10 ◎ Fan-forming type Fig. 5 (a) 130 ° C 1 10/10 ◎ Fan forming type Fig. 5 (a) 130 ° C 0.01 10/10 ◎ (Comparative example) No molding Fig. 4 Room temperature 100 5/10 △ No molding Fig. 4 Room temperature 1 6/10 △ No molding Fig. 4 Room temperature 0.01 7/10 △ No molding Fig. 4 50 ° C 1 3/10 ^{* 1} × No molding Fig. 4 130 ° C 10/10 ^{* 2} × ^{* 1 The} gripper was deformed seven times. ^{* 2} All grippers were deformed and could not be measured.

From the results shown in Table 1, it can be seen that when the measurement was performed by the method of the present invention, the test hardly failed, and the evaluation could be performed efficiently. On the other hand, when the conventional method is used, the success rate is only 50 to 60% even under the room temperature condition, and the success rate is remarkably reduced under the temperature rising condition, which is not practical.

Example 2 A fatigue test was performed using a sample piece prepared in the same manner as in Example 1. The results obtained are as shown in Table 2.

Table 2 Results of Fatigue Test Strand Grab Vibration Frequency Test Results End Shape Groove Shape Temperature (Hz) (Number of Successful Evaluations / Number of Trials) (Invention) Sector Forming Figure 5 (a) Room Temperature 2 15/15 ◎ Sector Molding Fig. 5 (a) Room temperature 0.2 15/15 ◎ Sector formation Fig. 5 (a) 150 ° C 2 14/15 ○ According to the method of the present invention, a sufficiently high success rate is obtained even in a fatigue test at room temperature and elevated temperature. Can be achieved.

Example 3 As a test piece, a CFRP strand that had been subjected to a curing treatment at 120 ° C. for 2 hours using carbon fiber T400-3K (manufactured by Toray) and epoxy resin Epikote 828 (manufactured by Yuka Shell) was prepared. This strand was evaluated in the same manner as in Example 1. The results obtained are as shown in Table 3.

Table 3 Results of Static Tensile Test Strand Gripping Device Load Speed Test Results End Shape Groove Shape Temperature (mm / min) (Success Number of Evaluations / Number of Trials) (Invention) Sector Forming FIG. 5 (a) Room temperature 100 10 / 10 ◎ Fan-forming type Fig. 5 (a) Room temperature 1 10/10 ◎ Fan-forming type Fig. 5 (a) Room temperature 0.01 10/10 ◎ Fan-forming type Fig. 5 (a) 130 ℃ 100 10/10 ◎ Fan-forming type Fig. 5 (a) 130 ° C 1 10/10 ◎ Fan forming type Fig. 5 (a) 130 ° C 0.01 10/10 ◎ (Comparative example) No molding Fig. 4 Room temperature 100 6/10 △ No molding Fig. 4 Room temperature 1 6/10 △ No molding Fig. 4 Room temperature 0.01 7/10 △ No molding Fig. 4 50 ° C 1 1/10 ^{* 1} × No molding Fig. 4 110 ° C 10/10 ^{* 2} × ^{* 1 The} gripping tool was deformed nine times in failure. ^{* 2} All grippers were deformed and could not be measured.

From the results shown in Table 3, it can be seen that when the measurement was performed by the method of the present invention, the test hardly failed and the evaluation could be performed efficiently. On the other hand, when the conventional method is used, the success rate is only about 60% even under the room temperature condition, and the success rate is significantly reduced under the elevated temperature condition, which is not practical.

Example 4 A fatigue test was performed using a sample piece prepared in the same manner as in Example 3. The results obtained are as shown in Table 4.

Table 4 Results of Fatigue Test Strand Grab Vibration Frequency Test Result End Shape Groove Shape Temperature (Hz) (Number of Successful Evaluations / Number of Trials) (Invention) Sector Forming Figure 5 (a) Room Temperature 2 15/15 ◎ Sector Molding Fig. 5 (a) Room temperature 0.2 15/15 ◎ Fan forming Fig. 5 (a) 150 ℃ 0.2 13/15 ○

According to the method of the present invention, it can be seen that a sufficiently high success rate can be achieved even in a fatigue test under room temperature and elevated temperature conditions.

[0046]

According to the present invention, it is possible to measure the viscoelasticity of a resin-impregnated strand with high accuracy and high efficiency, and to perform the measurement with high accuracy and high efficiency even under a temperature rising condition. It is as described in the section of [Summary of the Invention].

[Brief description of the drawings]

FIG. 1 is a diagram showing a structure of a gripper used for reinforcing a terminal end of a strand test piece.

FIG. 2 is a schematic view showing a tensile test of a strand test piece.

FIG. 3 is a diagram showing the shape of a terminal end of a resin-impregnated strand that can be used in the method of the present invention.

FIG. 4 is a diagram showing a structure of a gripping tool used in a conventional tensile test device.

FIG. 5 is a diagram showing the structure of a gripping tool used in the tensile test device of the present invention.

FIG. 6 is a schematic view showing a tensile test apparatus of the present invention.

[Explanation of symbols]

 4 Strand 6 Strand fixing groove 7 Gripping tool 61 Constant temperature bath

Claims (4)

[Claims] 1. A tensile tester for measuring viscoelasticity by applying tension to a resin-impregnated strand test piece, comprising: a gripper for reinforcing both ends of the strand test piece; A tensile test device, characterized in that a width of a groove for fixing a strand test piece provided in a tool has a portion that becomes wider in a direction in which tension is applied. 2. A tensile tester for measuring viscoelasticity by applying tension to a strand test piece under elevated temperature conditions,
A tensile test apparatus comprising a constant temperature bath capable of substantially heating only a measured portion of a strand test piece. 3. A method for measuring viscoelasticity by applying tension to a resin-impregnated strand test specimen, comprising the following steps: (1) a step of forming the end of the strand test piece wider than the diameter of the original strand test piece; and (2) a direction in which tension is applied to a gripper for fixing the end of the strand test piece. (3) a step of providing a groove having a portion whose width increases toward (3), and (3) a step of fixing the strand test piece obtained in the step (1) so as to be fitted to the gripper obtained in the step (2). (4) a step of measuring the viscoelasticity by applying tension to the strand test piece whose end is fixed in the step (3). 4. A method for measuring the viscoelasticity of a resin-impregnated strand, which comprises heating substantially only the portion to be measured of the resin-impregnated strand using a tensile tester and measuring the viscoelasticity thereof.