JPS6122268Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a compressive strength test jig, and in particular to a jig that can be suitably used for compressive strength tests of plate materials such as composite materials, that is, both static compressive strength tests and compressive fatigue strength tests. It is something.

Conventionally, materials such as glass fiber reinforced plastics (GFRP-glass fiber, reinforced plastics), which is a material made of glass fiber as a reinforcing material and impregnated with unsaturated polyester resin, or FRM (fiber, reinforced matal) have been used in the past. For composite materials such as JIS K 7208, ASTM
D 695 stipulates a method for static compressive strength testing, but even when actually tested in accordance with this method, it tends to be difficult to obtain normal compressive fracture near the center of the test piece. Furthermore, no test method has yet been determined for compressive fatigue strength testing.

The present invention has been developed in view of the above circumstances, and it is important to note that when compressive force is applied to a plate-shaped test piece to determine its static strength, fatigue strength, etc., the test piece may buckle. This was done with the purpose of providing a jig that prevents this. In order to achieve this purpose, the jig according to the present invention includes a patch plate that is applied to both sides of one gripping part of the test specimen and has a length such that one end protrudes from the chuck of the testing machine, and a , a jig main body having opposing parts facing each other with a predetermined gap on both sides of the test piece, and attached to a portion protruding from the chuck of the caul plate; A buckling prevention plate that can be contacted directly or indirectly through a friction reducing member is screwed onto both sides of the part between the gauge points, and the opposing part of the jig main body,
It is configured to include an appropriate number of push screws that abut the buckling prevention plate at the tip and press the buckling prevention plate against the test piece.

If such a jig is used, the buckling stop plate, which is prevented from moving in the direction perpendicular to the plate surface of the test piece by the jig body, effectively prevents the test piece from buckling, making it easy to buckle. Not only can you accurately determine the static compressive strength of a board, but you can also accurately determine the tensile-compressive fatigue strength or compressive-compressive fatigue strength, especially for composite materials whose compressive strength is lower than their tensile strength. The above-mentioned strength characteristics of the material can be accurately known without being affected by buckling or bending deformation.

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the compressive strength test jig according to the present invention will be described in detail below with reference to the drawings.

In Fig. 1, 2 is a load device, a load indicator,
It is a chuck of a known material testing machine consisting of a deformation indicator, etc., and is designed to clamp both ends of a plate-shaped test piece 4 finished into a predetermined shape via a backing plate 5 and apply a tensile or compressive load. It's getting old. The upper end of the backing plate 5 is made to protrude from the chuck 2 by a certain length, and the jig body 8 of the jig 6 is attached to this protrusion. The jig main body 8 consists of two symmetrical opposing members 10 each having a protrusion 9 with a rectangular cross section formed along one side of a rectangular plate, and the protrusion 9 protrudes from the chuck 2 of the backing plate 5. The bolt 12 and nut 14 are tightened.

In the gap formed in the jig main body 8, a buckling prevention plate 16 and a friction reducing plate 18 are accommodated on both sides of the test piece 4 with some margin, respectively.
It is lightly pressed against the test piece 4 by four push screws 20 screwed into each opposing member 10.

Note that the vertical distance P between the push screws 20 is slightly larger than the gauge distance L of the test piece 4, and the lateral distance between the push screws 20 is equal to the distance between the parallel parts of the test piece 4. It is set to be slightly larger than the width W. The anti-buckling plate 16, which the tip of the push screw 20 comes into contact with, is provided with a suitable counterbore 24, so that there is a risk that the anti-buckling plate 16 will fall even if the push screw 20 is only lightly tightened. It is made sure that there is no such thing.

In addition, the jig main body 8, the buckling prevention plate 16, and the friction reducing plate 1 are located in the area surrounded by the four push screws 20.
8, a rectangular notch hole 22 in the longitudinal direction of the test piece 4.
is formed so that changes in the vicinity of the center of the test piece 4 during the compression test can be observed.
Further, as the friction reducing plate 18, a material having a low coefficient of friction, for example, a thin ceramic plate is preferably used.

Using the jig 6 configured in this manner, for example, a material having a thickness of about 3 mm, such as glass fiber reinforced plastic, etc.
When testing the in-plane (edgewise) compressive properties of a laminate of approximately 100 to 100 mm, a test piece 4 having a predetermined shape is first manufactured by machining. Next, the gripping portions at both ends of the test piece 4 are held between the chucks 2 at the upper and lower parts of the testing machine via the backing plates 5. At this time, one (for example, upper) gripping part of the test piece 4 and a part of the backing plate 5 that clamps it are made to protrude from the chuck 2 by a certain length. In this state, the test piece 4 and the parts of the backing plate 5 protruding from the chuck 2 are held between the jig body 8 and tightened with two sets of bolts 12 and nuts 14 to fix the jig body 8.

Thereafter, the anti-buckling plate 16 and the friction reducing plate 18 are inserted into the two gaps formed between the test piece 4 and the jig main body 8, respectively, and The anti-buckling plates 16 are pushed by the two push screws 20 so that the two anti-buckling plates 16 lightly sandwich the test piece 4 from both sides with the friction reducing plate 18 in between. The tip of the push screw 20 should fit into the counterbore 24 provided in the buckling prevention plate 16, and the force for tightening the push screw 20 should be such that it can be lightly tightened with fingers, but should not be tightened too hard.

After doing this, operate the compression tester and
If a compressive load is applied to the test piece 4, the buckling prevention plate 16
The buckling prevention plate 16 is prevented from moving in the direction perpendicular to the plate surface of the test piece 4 by the jig main body 8 and the push screw 20 that are firmly fixed to the backing plate 5. Normal compression is performed along the lines. In addition, at this time, the test piece 4 and the buckling prevention plate 1
If a frictional force is generated between the specimen 4 and the test piece 6, there is a problem of load loss and heat generation, so thin ceramic plates or the like having a low coefficient of friction are inserted on both sides of the test specimen 4 as friction reducing plates 18.

In this way, the compression properties of thin sheets of laminates such as glass fiber reinforced plastics can be accurately obtained without the risk of buckling or bending deformation, and changes in the specimen during compression tests can be easily made without being hindered by jigs. Moreover, the increase in frictional force caused by mounting the jig can also be effectively avoided.

Additionally, in place of the directional buckling prevention plate 16 and the friction reducing plate 18, a buckling prevention plate 30 shown in FIGS. 3 and 4 may be used. This buckling prevention plate 30 does not require a friction reducing member.
It is brought into direct contact with the test piece 4. Therefore, the surface of the anti-buckling plate 30 that comes into contact with the test piece 4 is provided with the test piece 4.
A large number of V-shaped grooves 32 are cut in the longitudinal direction of the shaft to reduce frictional force. Also, buckling prevention plate 30
Stepped holes 34 are provided at the four corners of the frame for attaching hexagon socket head bolts, and a V-shaped hole is provided in the center.
A cutout hole 36 for observing the compression state is provided in the direction of the shaped groove 32.

It should be noted that the present invention is by no means limited to the specific examples exemplified above, and various modifications and improvements can be made based on the knowledge of those skilled in the art without departing from the spirit of the present invention.

For example, the jig main body may have a structure in which the opposing member 10 and the backing plate 5 in the above embodiment are fixed together.
It is also possible to construct it from a member. In this case, the jig main body is fixed at the same time when the test piece 4 is clamped into the chuck 2, so there is no need to tighten the bolt 12, and the opposing member The mounting rigidity of 10 is also improved. Further, as shown in FIG. 5, the jig main body 40 has an integral structure, and a clamp 44 that is rotatably coupled to a bolt 42 and tightened by turning the bolt 42 and one of the jig main bodies 40 are opposed to each other. The protruding part of the backing plate may be sandwiched and fixed between the part 46 and the part 46. The method of pressing the buckling prevention plate (not shown) against the test piece using the push bolt 48 is the same as in the previous embodiment.

[Brief explanation of the drawing]

Fig. 1 is a front view of one embodiment of the compressive strength test jig according to the present invention, Fig. 2 is a cross-sectional view taken from Fig. 1, Fig. 3 is a front view of another embodiment of the present invention, and Fig. 4 The figure is a - sectional view in FIG. 3. Fifth
The figure is a perspective view showing a jig main body in another embodiment of the present invention. 4: Test piece, 6: Jig, 5: Back plate, 8, 4
0: jig main body, 10: opposing member, 16, 30: buckling prevention plate, 18: friction reducing plate, 20, 48: push screw, 46: opposing part.

Claims (1)

[Claims for Utility Model Registration] Compressive force is applied to a plate-shaped test piece to determine its static strength,
A jig for preventing buckling of a test piece when determining fatigue strength, which is applied to both sides of one grip of the test piece, with one end protruding from the chuck of the testing machine. a jig main body that is attached to a portion of the caul plate that protrudes from the chuck, the jig body having opposing parts facing each other with a certain gap on both sides of the test piece in use, and that is attached to a portion of the caul plate that protrudes from the chuck; an anti-buckling plate inserted into the gap and capable of contacting at least both surfaces of the portion between the gauge marks of the test piece, either directly or indirectly through a friction reducing member, and screwed onto the opposing portion of the jig main body; A compressive strength test jig comprising: an appropriate number of push screws that abut the buckling prevention plate at the tip thereof and press the buckling prevention plate against the test piece.