Constitutive relation of elastic materials with different elastic moduli in tension and compression

Almost all materials show different characteristics of the elastic modulus when they are in tension or compression.The mining potential of the properties of various materials, the development of new materials, and new research has become a trend. With different tension and compression modulus of elasticity of the characteristics of the material, if classical elasticity theory is used to analyze the calculation a lot of errors will be made.After applying the principle of strain invariant, a new kind of constitutive relation is given out for the elastic isotropy materials with different elastic moduli in tension and compression, which is more convenient in the iterative process to solve the elastic materials with different elastic moduli in tension and compression.