JPS60129641A - Tensile and compression test of anisotropic material - Google Patents

Abstract

PURPOSE:To enable accurate measurement of inherent strength in a circumferential direction, by pressing the non-compressive material being filled in a thin walled cylindrical specimen comprising an anisotropic material to allow uniform pressure to act on the inner wall of the specimen and loading tensile or compression load to the specimen in the circumferential direction thereof. CONSTITUTION:A thin walled cylindrical specimen 1 comprising an anisotropic material is held on a base plate without restricting both end parts thereof and a non-compressive material 4 such as water is allowed to fill the cylindrical specimen 1 through a flexible film 3. In the next step, a movable plate 5 is inserted into the cylindrical specimen 1 from the open end thereof. When load W is applied to the movable plate 5 by a loading apparatus, the internal pressure (P) of the non-compressive material 4 increases in proportion to load W and, therefore, the load W is increased until the cylindrical specimen 1 is destructed and tensile test load can be loaded to the cylindrical specimen 1 in the circumferential direction thereof. As a result, the strength of the cylindrical specimen 1 can be accurately measured.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for performing tensile and compression testing of anisotropic materials.

In tensile and compression tests on materials, especially on anisotropic materials, locally concentrated stress occurs at the part where the sample is gripped for tension and in contact with the indenter for compression. It is difficult to determine the exact strength of the sample.Regardless of whether there is a reinforcing material or not, a large concentrated stress is generally generated at the gripping part of the specimen, so it often breaks at this part, and this concentrated stress Since there is no way to know the value of , it has been difficult to know the strength value unique to the material. Furthermore, even if there is no fracture at the sample gripping part, if the strength in the direction perpendicular to the fibers is significantly smaller than the strength in the direction parallel to the fibers, such as in fiber-reinforced composite materials (FRP), the fibers should be removed. Since the fracture occurs in the plane parallel to the fibers before the fracture occurs in the transverse direction, it is not possible to estimate the strength value for the load in the fiber direction, where the strength is greater.

Furthermore, in tests conducted by applying internal pressure to a thin-walled cylindrical sample with both ends closed, it is impossible to include pure tensile stress because biaxial stress in the axial and circumferential directions is always generated on the sample wall. Can not.

However, large locally concentrated stress occurs near the contact area between the sample and the indenter, resulting in the sample turning over and breaking, which is generally referred to as the blooming phenomenon.Moreover, the stress state at this time is irregular and complex. There is no way to know this value, making it extremely difficult to estimate the sample strength.

The present invention was made in order to solve the above-mentioned drawbacks of the conventional method. When applying uniform pressure by an incompressible body to the inner or outer wall of a cylindrical sample, the stress that acts in the axial direction of the cylindrical sample The tensile and compression testing method of the present invention is performed by completely removing the
A thin cylindrical sample made of an anisotropic material is pressurized with an incompressible body filled within the sample or between the sample and a pressure-resistant container surrounding it, with its ends unrestrained, thereby causing the inner wall of the sample or It is characterized by applying uniform pressure to the outer wall and applying a tensile or compressive load in the circumferential direction to the sample.

According to the test method of the present invention, a test load is applied only in the circumferential direction of a cylindrical sample, thereby making it possible to measure the specific strength of the sample in a specific direction. Since there is no gripping part or contact part with an indenter for compression, there is no local destruction of the sample, and accurate sample strength can be determined. The method of the present invention will be explained in detail below with reference to the drawings. ・ Stabilize the sample by inserting it into one end, but do not restrain both ends. In other words, the sample is held in a state where no stress is applied from the outside, and an incompressible body such as water, oil, or grease is placed inside the cylindrical sample 1 either directly or through a flexible membrane 3' made of a polymeric material. By filling the incompressible body 4 and pressurizing it, uniform pressure is applied to the inner wall of the sample.The above-mentioned pressurization of the incompressible body 4 is performed by moving the movable plate 5 from the open end of the sample 1 using an appropriate loading device. The internal pressure p of the incompressible body 4 increases in proportion to the load W, so the load W is increased until the sample 1 breaks, and the sample l
A tensile test load can be applied in the circumferential direction.

This is a pressure-resistant multi-stage packing that has a self-locking function that can follow the increase in diameter.

In the tensile test of the anisotropic material described above, the tensile strength F of the sample is given by, where d is the average diameter of the sample, t is the wall thickness, A is the cylindrical inner area, and W is the maximum load.

In addition, in FIG. 2, which shows a state in which a sample is subjected to a compression test, a thin cylindrical sample 11 made of an anisotropic material is stabilized by being fitted and held within a convex portion of a substrate 12 having an annular convex portion. sample 11 without restraining its ends, i.e. sample 11
A non-compressible material 14 such as water, oil, or grease is filled between the sample 11 and a cylindrical pressure-resistant container 17 surrounding it, either directly or via a flexible membrane 13. By pressurizing it, a pressure q of 14 is applied to the outer wall of the sample, and a compressive load is applied to the sample 11 in the circumferential direction.

Note that the flexible membrane 13 can be divided as shown in the figure depending on the sample size. Further, in the figure, reference numeral 16 indicates a pressure-resistant multi-stage packing having a self-locking function.

In such a compression test of an anisotropic material, the compressive strength F2 of the sample is given by: where D is the outer diameter and d is the inner diameter of the sample.

In the tension and compression tests shown in Figures 1 and 2 above,
In either case, uniform pressure is applied to the inner or outer wall of the sample without restraining the sample end.

[Brief explanation of drawings]

FIGS. 1 and 2 are cross-sectional views showing how a sample is subjected to tension and compression tests according to the method of the present invention. 1.11・φ sample, 4,14・fist incompressible body. Taste 0) Sa\Q)

Claims (1)

[Claims] ll, ; A thin cylindrical sample made of an anisotropic material is pressed with an incompressible body filled inside the sample without restraining its ends, thereby applying a uniform pressure to the inner wall of the sample, Applying a tensile load in the circumferential direction to □, pressurizes the incompressible material filled between the sample and the pressure-resistant container surrounding it, thereby causing the outside of the sample and the wall to be A compression test method for anisotropic materials characterized by applying pressure and applying a compression load in the circumferential direction to the sample.