JPH0580979B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a tensile test piece, and more particularly to a tensile test piece that can accurately measure the amount of elongation of an extremely thin or extremely fine test piece.

[Conventional technology]

Generally, a tensile test is performed to determine the relationship between stress and strain in a material, and the amount of elongation of the material is measured by determining the amount of change in the distance between gauge points before and after the tensile test. Furthermore, in order to determine the amount of elongation of a material through a tensile test, an extensometer is attached directly to the surface of a test piece, and the amount of elongation is determined from the output of the extensometer.

[Problem that the invention seeks to solve]

However, although the conventional elongation detection method described above can be carried out without any inconvenience for test pieces with a thickness of 2 mm or more and a diameter of 3 mm or more, For the test piece, the weight of the extensometer itself affected the measurement results, making it impossible to determine accurate stress and strain in the material. Furthermore, the gripping portion of the ultrathin and ultrafine test piece was small and lacked rigidity, making it difficult to grip it with the gripper on the testing machine side.

Furthermore, in order to determine the amount of elongation of an extremely thin test piece, there was a problem in that stress was concentrated on the surface of the test piece when gauge marks were marked on the surface of the test piece.

In addition, when the test piece is a thin filament, it is impossible to attach an extensometer, and there is a problem that the test piece cannot be securely gripped due to slipping at the gripping part.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a tensile test piece that allows the amount of elongation of an ultra-thin, ultra-fine test piece to be accurately measured in a non-contact manner.

[Means for solving problems]

In the present invention, an elongation detection member is fixed to the gripping portions at both ends of the parallel portion of the test piece, and the free end of the elongation detection means is attached to the gripping portion at a known dimensional interval before the test load is applied. It is composed of a pair of extension detection pieces that are cantilevered against each other.

[Effect]

When the test load of the tensile test is applied to the specimen,
Since the elongation detection piece of the elongation detection member moves together with the gripper of the testing machine, the amount of elongation of the test piece can be measured by measuring the amount of displacement between the free ends of the elongation detection piece before and after the tensile test. .

〔Example〕

Examples of the tensile test piece according to the present invention will be described below with reference to the drawings.

Figure 1 shows an example in which the present invention is applied to a test piece with ^an extremely thin plate thickness.
The target is 30μm, and it is in the form of a JIS13 B test piece. In the same figure, a test piece designated as a whole by reference numeral 1 has gripping portions 2 and 3 at both ends and a parallel portion 4. Slits 5, 5 of a predetermined length are formed on both sides of the parallel portion 4, and the center of the band-shaped portion left outside of the slits 5, 5 is cut along the cutting line 6 and extends into detection pieces 7, 7. has been done. Parallel portion 4 at both ends of the slits 5, 5
Curved shoulders 8 are formed at portions corresponding to both ends.

Although punching may be used to form the slits 5, 5, it is preferable to form the slits by etching using an etching solution in order to eliminate processing distortion.

Further, the gripping parts 2 and 3 of the test piece described above are extremely thin and will cause slippage if left as is, so it is effective to attach adhesive tape containing glass fiber to the surface of the gripping parts.

In order to determine the stress strain of the test piece 1 configured as described above, the grip portions 2 and 3 of the test piece 1 may be gripped with the grippers of a tensile tester and a test load applied thereto. The parallel portion 4 of the test piece 1 is stretched by the test load and breaks at the break line 9 as shown in FIG. During this time, no test load is applied to the extension detection pieces 7, 7, and the extension detection pieces 7, 7 move together with the grip portions 2, 3. Therefore, the amount of displacement in the dimension between the free ends of the elongation detection pieces 7, 7 when the fractured surfaces of the test pieces are brought together after rupture represents the amount of elongation.

In addition, in order to measure the size of the gap between the free ends of the extension detection pieces 7, 7, as shown in FIG. The size of the gap can be determined by placing a laser receiver 11 on the side and measuring the amount of laser light that has passed through the gap.

Next, an example in which the present invention is applied to a filamentous test piece will be described with reference to FIG. 4.

Reference numeral 12 indicates a wire test piece, and in this example, a stainless steel wire with a diameter of 0.05 mm to 0.15 mm is used. Elongation detection cylinders 13 and 14 made of acrylic resin are respectively fixed to both ends of the filamentous test piece 12 and supported in a cantilevered manner. Before the test, a gap 8 between the free ends of these extension detection cylinders 13 and 14 is set to a known size. In order to increase rigidity, the gripping portion of the test piece is preferably wrapped with copper wire and fixed with an adhesive, and further extended to fix the detection tubes 13, 14 and the test piece 12 with a strong adhesive.

FIG. 5 shows another embodiment of the present invention,
This is a suitable example for a filamentous test piece, such as a wire.
This is an example in which detection pieces 16 and 17 are provided extending at both ends of the wire 15, and the gripping portions of the wire 15 are joined with an adhesive 18. Even in this case, the wire and the extending detection piece are left unrestrained except for the grip portion.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, the detection piece is cantilever-supported by extending to the gripping part of the tensile test piece, and the amount of extension of the test piece is measured by the amount of change in the distance between the free ends. This makes it possible to easily and accurately measure the amount of elongation of ultra-thin strip test pieces and ultra-fine wire test pieces that cannot be directly attached with an extensometer.

[Brief explanation of the drawing]

Fig. 1 is a plan view showing the state of the tensile test piece according to the present invention before the test, Fig. 2 is a plan view showing the state of the same test piece after the test, and Fig. 3 is a plan view showing the state of the test piece after the test. FIG. 4 is a perspective view showing the measurement state of the amount of elongation of the piece, FIG. 4 is a longitudinal sectional view showing a test piece according to another embodiment of the present invention, and FIG. 5 is a plane view showing a test piece according to still another embodiment. It is a diagram. 1... Test piece, 2, 3... Gripping part, 4... Parallel part, 5... Slit, 7... Extension detection piece, 12
...striated test piece.

Claims (1)

[Scope of Claims] 1. An elongation detection member is fixed to the claws at both ends of the parallel portion of the test piece, and the free end of the elongation detection member is fixed at the above-mentioned position with a known dimensional interval before the test load is applied. A tensile test piece comprising a pair of elongation detection pieces supported in a cantilever manner with respect to a grip part. 2. Claims characterized in that the elongation detection member is formed by cutting the center of an outer band-shaped portion of a slit formed in the longitudinal direction on both sides of the parallel portion of the test piece. The tensile test piece according to item 1. 3. The elongation amount detection member is an elongation detection tube that is fitted concentrically to the gripping portion of the rod-shaped test piece, and
A tensile test piece according to claim 1, characterized in that its free end is cantilevered against the grip part at a known dimensional distance before application of the test load.