The development history of impact tests

With the development of the times: Shabi lock-shaped impact test, Shabi V-shaped impact test and Shabi Mei's impact test have been paid attention to. Before 1968, the United States used the Champian lock-shaped impact test method, but this test method had a disadvantage: because the lock-shaped notch was too blunt, it was determined that the brittle transition temperature was lower than the brittle fracture temperature of the structure. Therefore, after 68 years, standard Champian V-type samples were used in the ASTM specifications, so many V-type samples and Mei's impact samples were used now. Generally speaking, there are many V-shaped gaps in Europe and the United States, while Russia uses the Shabimei sample.

The principle of the impact test machine is the law of conservation of energy, and the impact work is calculated based on the amount of loss after the pendulum breaks the impact sample. However, this test method has a natural disadvantage. It cannot directly display the internal and displacement curve like a tensile tester, because the result we measure can only be impact work. The impact work is the unit of energy, and its unit is Joule, and the formula for energy is:

W =FS means impact work = force * displacement, so no matter which of these two variables changes, it will cause changes in impact work, especially displacement. Therefore, the impact work value cannot directly explain the toughness of the material, and cannot describe the changes caused by the material during the strike process. It can only be used as a reference. In order to solve this problem, people invented instrumented impact test methods.

There were almost no impact tests in our country before liberation. After liberation, we learned comprehensively about the Soviet Union. It was not until 1963 that there was an impact test standard GB229-1963. The standard we are using now is GB/T229-2007 "Metal Materials Shabby Pendulum Test Method", which is also applicable to the US and European standards.