The criteria and difficulties in determining the quality of tensile testing machine fixtures

The criteria and difficulties in determining the quality of tensile testing machine fixtures
It is difficult to determine the quality of the tensile tester fixture. Due to the particularity of the fixture structure, it is sometimes difficult for us to determine which sample it is more suitable for. It is usually judged from the following three points.
1. Whether the fixture is convenient and safe to use.
2. Whether the clamping is reliable and there is no slippage.
3. During the test, the sample breakpoint is good. The data is small discrete. (i.e., the sample is constantly jawed, inside the jaw, parallel section or outside the gauge distance)
There are several types of materials that have special characteristics and applicable environments. So far, there are not many solutions.
1. Due to the high hardness of the sample, the internal structure is relatively loose, the stress is uneven during the tensile test, and the jaws holding the sample are prone to wear, etc., the fixture has not been well solved. In the past, it was done by clamping aluminum foil, but it took four pieces of aluminum foil in one experiment, which was too much waste. Now, a tensile tester fixture is used to spray the cartilage, and the slipping problem has been solved, but the fracture position has never been ideal, and 10 samples can only succeed about half.
2. For materials with large deformation, it is difficult to clamp due to excessive deformation, and the design of fixtures is also a difficult point.
3. For tests that need to be done in high temperature environments, the fixtures are also very high. They must be resistant to high temperatures, and do not deform, and have small volumes. Therefore, it is also difficult for ordinary test machine manufacturers to handle.
4. For large batch and high frequency tests, fully automatic clamping is generally used abroad, which is still a new topic for domestic testing machine manufacturers.
5. The fixtures required for inspection of finished and semi-finished products are a challenge for all test machine manufacturers.