Cyclic Response and Constitutive Model Study of G20Mn5QT Cast Steel

Abstract

A series of cyclic loading tests of G20Mn5QT cast steel are carried out at the strain ratio of − 1. The results of tests show that the G20Mn5QT cast steel has the similar tendency in cyclic softening with different constant strain amplitude. A slight strain softening is observed, and then the stress states keep steady during the remaining cycles. A new damage variable is proposed considering the effects of strength degeneration within two inner variables which are the maximum equivalent plastic strain and the equivalent plastic strain increment. The damage variable provides better insight into the multiaxial cyclic loading and gives a reasonable prediction of failure under the loading history of constant strain amplitude. The proposed damage variable is further introduced in the cyclic constitutive model by the user subroutine interfaces VUMAT by the software ABAQUS. The relationships between the equivalent plastic strain and the damage variable, Young’s modulus and yield strength are finally put forward as it is expedient to get the equivalent plastic strain in the numerical analysis.