Criteria for Discussing the Results of Experimental Studies of Plastic and Brittle Materials

In experiments on axial tension and compression of solid cylinders, only some components of the deformation can be measured instrumentally, and the stress components cannot be directly measured at all. In order to discuss the test results of ductile and brittle materials, we propose to use a new equation (criterion). It is obtained by integrating the differential equation of axial motion, which uses the generalized Hooke's law and boundary conditions on the base and side surface of the cylindrical sample. The equation relates the load to axial and circumferential deformations and describes the experimental data at all levels of deformation of materials at the same values of the Lame constants.