JPS5916210B2 - Compression test equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention mainly relates to a compression test of non-metallic materials and an apparatus used for testing.

In general, non-metallic materials often have different tensile and compressive properties than metallic materials, and therefore compression tests are essential testing methods for non-metallic materials.

Conventionally, this type of compression test for nonmetallic materials has been performed by compressing a cylindrical or prismatic sample at a constant speed between the flat end faces of a pair of copper indenters, but it is difficult to compress the sample uniformly. The problem was that it was extremely difficult. In other words, unless the parallelism of both end faces of the sample is maintained extremely well, the load will be applied with a gap created between the end face of the sample and the contact surface of the indenter, and as a result, the load will be applied to only a portion of both ends of the sample. A large amount of stress will be generated, and this part will be the first to fail. In this case, there is no way to know what kind of stress state the sample is in, so it is impossible to know the original strength of the material. Furthermore, when the parallelism of both end faces of the sample is insufficient as described above, an extreme eccentric load is applied to the sample, and the strain on the sample varies greatly depending on the measurement point. In addition, if the 10 flatness of both end faces of the sample is not good, for example, if the end face has serrated irregularities, the outer edge portion of the end face of the sample will turn outward as the compressive load from the indenter increases (blooming phenomenon). ), so it is not possible to determine the original strength of the sample in the same way as in the above case15. In this way, when performing a compression test, it is necessary to maintain sufficiently good flatness and parallelism at the end surface of the sample, but even if these conditions are satisfied, compression using the indenter described above is not necessary. Then, due to the difference between the material constants of the 20 samples and the material constants of the indenter, shear stress is generated in the contact area, which also causes a blooming phenomenon, so the original strength of the material cannot be determined.

The present invention was made in view of the disadvantages of the conventional compression test apparatuses described above, and when applying compressive force between both end faces of a sample, unlike the conventional apparatus, the present invention does not use an indenter to bring solids into contact with each other. Insert both ends of the sample into a pressure chamber filled with working fluid, bring the sample end faces into contact with the liquid, apply pressure to the working fluid in this state, and check the flatness and parallelism of the sample end faces, as well as the relationship between the sample end faces and the sample. 35 characterized in that it is possible to apply a uniformly distributed load to the end face of the sample regardless of the difference in the material constants of the indenter, and furthermore, the contact friction is prevented from acting when the area of the end face of the sample increases due to compression in the axial direction. It is something.

Therefore, according to the test apparatus of the present invention, even if there are irregularities on the sample end face, no local concentrated stress is generated, and furthermore, no shear stress is generated due to the difference in material constants, so that the sample The edges of the sample do not break, and all sample breakage occurs at the center of the length of the sample, allowing the original strength of the material to be determined.

Furthermore, since the eccentric load is completely removed, the strain or stress generated in the sample does not differ depending on the measurement point. Hereinafter, embodiments of the present invention will be described in detail based on the drawings. In FIG. This is a drive unit that pumps working fluid to compress the air.

As shown in detail in FIG. 2, the sample compression section 1 includes a binder 3 that is disposed opposite to a pair of clamping sections 3a and 3b that can be brought into and out of contact with each other. Pressure chamber forming bodies 5, 5 are provided to form a pair of pressure chambers 4, 4 for applying hydraulic pressure to both end surfaces.

The pressure chamber forming bodies 5, 5 are each composed of a container body 6 and a lid 7, and the pressure chamber forming bodies 5, 5 are sandwiched between the binu 3 at a predetermined interval via a transparent pressure-resistant cover 8 installed between the two pressure chamber forming bodies 5, 5. The pressure chamber forming body 5,
5 and a pressure-resistant cover 8 are integrated, and a liquid receiving chamber 9 is formed within the pressure-resistant cover 8 between the pressure chamber forming bodies 5 and 5.

The pressure chamber forming bodies 5, 5 are provided with a through hole 10 through which the sample T is inserted in the opposite wall surface of the container body 6 facing the liquid receiving chamber 9, and the pressure chambers 4, 4 are provided with a through hole 10 through which the sample T is inserted. A pressure liquid inlet hole 11 and an air vent hole 12 are bored. Inside the pressure chambers 4, 4,
A multilayer pressure-resistant packing 14 is provided that exhibits a self-locking function in cooperation with the sample T inserted through the through hole 10 and seals the pressure chamber 4.

The multilayer pressure-resistant packing 14 has its outer periphery tightly fitted into the inner periphery of the container body, and has a tight fitting hole 15 bored in the center thereof.
The end of the sample T can be inserted through a green or other anti-friction material 16 which also serves as a sealing material, and the periphery is surrounded by a spring 1.
The pressure chamber 4 is brought into pressure contact with the inner wall of the container main body having the through hole 10 by an elastic body such as 7, thereby ensuring the initial airtightness of the pressure chamber 4. Note that the grease used as the anti-friction material 16 must be insoluble in the working fluid; for example, when turbine oil-based hydraulic fluid is used as the working fluid, fluorosilicone-based grease is suitable.

In addition, the liquid receiving chamber 9 has a liquid drain hole 1 formed in the pressure-resistant cover 8.
Nutrain gauge 21 is connected to the outside through the lead wire outlet hole 19 and the drain hole 18 is communicated with the liquid reservoir 20, and the nut train gauge 21 is attached to the sample T through the lead wire outlet hole 19.
A lead wire 22 is led out and connected to a recorder 23 that remotely displays the amount of strain.

Note that 24 in the figure indicates a gasket for sealing.

A drive unit 2 connected to the sample compression unit 1 is a motor 26 or a manually driven pump 2, as shown in FIG.
5. The pump 25 pumps the working liquid in the tank 28 sucked through the filter 27 at a rate of, for example, 2,000 ml.
It is compressed to k9/Md and sent out, and the pump 25
A relief valve 2 for setting a desired pressure is provided in the flow path connecting the pressurized liquid inlet holes 11, 11 of the sample compression section 1.
9. A flow rate control valve 30 that allows fine adjustment of the flow rate to adjust the speed at which the sample T is compressed, a check valve 31 that prevents backflow of the working fluid, and a pluton A Nunaba valve 34 is connected to protect the pressure sensor of a tubular pressure gauge 32 and a recorder 33 that converts pressure into an electrical signal and displays it remotely. In addition, 35 in the figure
and 36 indicate liquid reservoirs, but these are tank 28
It is common to

In order to use the compression testing apparatus having the above configuration, the sample T is mounted in advance as shown in FIG. The sample T is inserted into the force chamber 4, and its end is fitted into the tight fitting hole 15 of the multi-layer pressure-resistant packing 14 through an anti-friction material 16 such as green, so that the end surface of the sample T comes into contact with the working fluid. state. Note that the operation of inserting the end of the sample T into the tight fitting hole 15 of the multilayer pressure-resistant packing 14 is performed when the anti-friction material 16 exists between the two and the pressure-resistant packing 14 is urged by an elastic body such as a spring 17. Therefore, it can be done very easily.

When the pump 25 is operated after adjusting the relief valve 29 and the flow rate control valve 30, the working fluid flows into the force chamber 4 whose initial airtightness is ensured, and the internal pressure of the force chamber 4 is reduced. The pressure gradually increases and acts on the end face of the sample T and the multilayer sealing packing 14.

At the initial stage, the sample T is inserted relatively loosely into the tight fitting hole 15 of the pressure packing 14, but as the internal pressure of the pressure chamber 4 increases, the sample T and the pressure packing 14 are compressed in the axial direction. Then, they are expanded in the force direction perpendicular to the axial force direction by an amount determined by the pressure and Poisson's ratio, and the degree of adhesion between the pressure packing 14 and the sample T is increased in proportion to the increase in liquid pressure. It exhibits a locking function and reliably prevents leakage of working fluid. In this state, sample T
The frictional force increases with the degree of adhesion between the pressure packing 14 and the sample T.
The deformation of is not restricted. If the internal pressure of the pressure chamber 4 further increases, the sample T is strongly compressed in the direction of the axial force in accordance with the pressure, and eventually breaks at the central portion in the direction of the axial force. The compression speed up to this destruction can be adjusted by the flow control valve 30. Additionally, some leakage of working fluid occurs from the pressure chamber 4 during compression of the sample T;
It is sufficient to use a pump 25 with sufficient discharge volume to make the inflow volume larger than the leakage volume.Furthermore, in order to prevent direct contact between the sample T and the working fluid, the sample may be covered with a polymer film,
You can protect it by covering it with paint, green, etc. During the above compression test, the applied pressure and the resulting strain on the sample T are recorded by a recorder 33 equipped with a pressure sensor and a recorder 23 connected to the Nutrain gauge 21, respectively. It is also possible to directly draw a "stress-strain diagram" by inputting the data into a recorder.

In the first compression test mentioned above, the sample T was compressed in the axial direction by bringing the sample end into contact with the working fluid and applying pressure to the liquid, so that regardless of the unevenness of the sample end, the A uniformly distributed load can be applied to the end face, so there is no possibility of locally concentrated stress causing damage to that part, unlike in conventional compression tests using an indenter.
Furthermore, there is no possibility of fracture due to shear stress generated by contact friction of the sample end surface, and fracture of sample T due to compression generally occurs at the center in the axial direction, making it possible to determine the original strength of the material. .

In addition, regardless of the parallelism of both end faces of the sample, there is no longer an extreme eccentric load that is applied in the past.
The strain and stress generated in the sample T do not differ depending on the measurement point. As described above, according to the present invention, it is possible to provide a compression test device that can easily perform a compression test with an extremely simple configuration.

[Brief explanation of drawings]

FIG. 1 is a circuit configuration diagram of an embodiment of the present invention, and FIG. 2 is a sectional view of the sample compression section thereof. 4...pressure chamber, 10...through hole, 14...
...Pressure-resistant gasket, 15...Tight fit hole, 1
6... Anti-friction material, T... Sample.

Claims (1)

[Claims] 1.Equipped with a pair of pressure chambers into which a working liquid can be pressurized, a through hole through which each end of the sample is inserted is bored in the opposing walls of the pressure chambers, and the end of the sample is inserted into the pressure chambers. A multilayer pressure-resistant packing with a tight-fitting hole that is inserted through grease or other anti-friction material is provided, and these pressure-resistant packings are pressed against the wall surface with the through-hole by an elastic body. Compression test equipment.