Establishment And Application Of Multi-parameter Strength Theory For Brittle Materials

Brittle materials have been widely used in the production practice.Strength theory for brittle materials is one of the fundamental problems in materials science.The innovation and development in this area not only has academic significance,but also has important application value.However,there are many kinds of brittle materials with different properties,so it is necessary to put forward the hypothesis of strength theory from the theoretical end.The main contents of this paper are as follows:(1)Taking into account the different stress,especially the effect of hydrostatic pressure on the strength of brittle materials,a new strength theory with three parameters or four parameters is presented based on the theory of twin ?~2 strength theory.Based on the theory of twin T~2 strength theory,a new strength theory with three parameters or four parameters is presented.According to the special points in the experiment,we calculated the parameters of four new theoretical values and derived their mathematical expressions.I analyzed the principal stress space limit surface properties,and compared with other strength theory,discussed two kinds of three-parameter strength theory of stress state theory in common several prediction curve.(2)In the theoretical analysis,four kinds of new strength theory are similar in the limit surface in the principal stress space.They are closed in the stretch zone in the compression zone and opening along the surface of hydrostatic pressure shaft increases,the size limit between single shear strength theory and the twin shear strength theory.The limit line on ? plane is a hexagonal or twelve-sided shape,which is determined by the parameter values.The stretching meridian and the compressed meridian on the meridian plane are parabolic and the shape is determined by the ultimate stress ratio.(3)In the application of multi-parameter strength theory for brittle materials,I choose some experimental data in the construction of common concrete,rock and cast iron brittle materials.The data and the new theory of strength under different stress prediction curves are compared and discussed.The experiment results indicate that the three-parameter twin ?~2 strength theory is in good agreement with the experimental data of concrete and rock materials,and the three-parameter of twin T~2 strength theory is close to some cast iron material.On the meridian plane the four-parameter of twin ?~2 and twin T~2 strength theory are basically consistent with the experimental data of some concrete material properties.The four new theory improve the strength theory for brittle materials.