Bending test

Bending test is one of the basic methods to determine the mechanical properties of materials under bending load. Bending test is mainly used to determine the bending strength of brittle and low plastic materials (such as cast iron, high carbon steel, tool steel, etc.) and to reflect the deflection of plasticity index. Bending test can also be used to check the surface quality of materials. Bending test is carried out on universal material machine, with three-point bending and four-point bending loading methods (see Figure). The cross section of the sample is circular and rectangular, and the span is generally 10 times of the diameter. For brittle materials, bending test can only produce a small amount of plastic deformation, but for plastic materials, bending fracture strength can not be measured, but its ductility and uniformity can be tested. The bending test of plastic material is called cold bending test. During the test, load the sample to make it bend to a certain extent, and observe whether there is crack on the surface of the sample.