Firstly

the stress-strain relationship of mild steel damper under cyclic loading

i.e.the ideal elastic-plastic model

the bilinear kinematic hardening model and the mixed model are introduced respectively.At the same time

according to the simulation analysis of the mild steel damper with diamond-shaped opening by the finite element software ANSYS

the damping force hysteretic curves of the mild steel damper with diamond-shaped opening under different constitutive models are obtained.Then the advantages and the disadvantages of each model are compared and the reason of errors is analyzed.Secondly

the damping force hysteretic curves of the mild steel dampers with 90°

60°and 45°diamond-shaped opening on the basis of the mixed model are established.And then the mechanical parameters are compared with the results of the theoretical analysis.The analysis results show that the mechanical parameters of the mild steel damper with diamond-shaped opening under the mixed model are consistent with the theoretical results

and the damping force hysteretic curves under the mixed model are consistent with the test curves.All of these demonstrate that the mixed model is a relatively accurate constitutive model of the mild steel damper with diamond-shaped opening.