G.R Ahmadzadeh - Postdoctoral fellow
A Varvani-Farahani - Professor, Department of Mechanical Engineering, Ryerson University, ۳۵۰ Victoria Street, Toronto, Ontario M۵B ۲K۳, Canada

The present study predicts ratcheting response of 1070 steel samples using nonlinear kinematic hardening rules of Ohno-Wang (O-W), Jiang-Sehitoglu (J-S) and Ahmadzadeh-Varvani (A-V) under uniaxial stress cycles. The ratcheting values predicted based on the O-W model were noticeably influenced by the magnitude of exponents and the number of backstress components. The J-S kinematic hardening rule holding numerous constants, encountered the effect of stress level in ratcheting assessment. Taking into account both material and cyclic stress level dependent coefficients, the A-V hardening rule offered a simple framework to predict ratcheting strain over loading cycles. A comparative study of these hardening rules to assess ratcheting of 1070 steel samples undergoing uniaxial loading conditions resulted in a close agreement of the A-V, O-W and J-S models. The choice of hardening rules in the assessment of materials ratcheting was further discussed based on the complexity of the hardening rule, number of constants/coefficients required to characterize ratcheting response and CPU time required to run the models.

Ratcheting strain; Kinematic hardening rule; Mean stress; Uniaxial loading