The slope of each point on the static stress-strain curve is called tangent modulus. Generally speaking, the tangent modulus of a point is calculated by the ratio of stress variation to strain variation near the point. Different from metal materials, plastic materials are viscoelastic and the stress-strain curve is nonlinear, so the tangent modulus of each point is different. I hope to know the relevant modulus in engineering, and then put forward the tangent modulus, which is an expression of the macroscopic modulus in the inelastic limit range of materials. According to the definition, this modulus is the hardening modulus of the material after yield, which can be determined by tensile test. The ratio of it to elastic modulus is called plastic coefficient, which is used in various structural calculations, such as local stability calculation.
For example, the elastic modulus of Q235 steel is 2.03×lO5MPa, Poisson's ratio is 0.3, steel density is 7850kg/m3, tangent modulus is 6 100MPa, and damping ratio is 0.02.
Please adopt it. Thank you.