Research And Finite Element Realization Of Cyclic Ratcheting Constitutive Model Based On Plastic Strain Memory Recovery

Ratcheting behavior refers to the cyclic accumulation of plastic strain generated by asymmetric stress cyclic loading.In the work of engineering components will withstand asymmetric stress cyclic loading,such as pressure vessel,reactor structure,electronic packaging,ratcheting will affect the life of these components and the reliability of the structure.Therefore,the construction of cyclic constitutive model for ratcheting behavior has an important engineering application value,and it also promotes the development of the subject of solid mechanics.Since the last century,as an important research direction of solid mechanics,scholars have established many constitutive models based on ratcheting experiments,however,the cyclic constitutive models have their own limitations,a more reasonable and accurate constitutive model remains to be studied.In addition,the finite element software is widely used in the strength checking and deformation simulation of the engineering components.However,the finite element software has obvious defects in the prediction of material ratcheting strain,and can not meet the needs of the project.Therefore,it is necessary to transplant more reasonable constitutive models into finite element program,improve the prediction accuracy of finite element software,and promote the development of ratcheting constitutive model.The following work has been carried out in this paper.Based on the framework of unified visco-plasticity,a new cyclic constitutive model is proposed to describe the ratcheting behavior of cyclic hardening materials.In the proposed model,the memory surface for maximum plastic strain effect is introduced,and the dynamic recovery coefficient is added to the plastic strain memory term to reflect the effect of maximum plastic strain on isotropic deformation resistance.The definition of the Tanaka's non-proportionality is adopted to describe the multiaxial ratcheting deformation with different multiaxial loading paths.Comparing with the prediction with corresponding experimental results,it can be found that the uniaxial and multiaxial ratcheting of 316L stainless steel can be reasonably described by the model.Aiming at the practical application of engineering,in this paper,an optimized Ohno-Abdel-Karim model is proposed.Although the prediction accuracy is lower than the plastic strain memory effect model,it has a more simplified structure.The transplantation of finite element software is conducive to program convergence and is consistent with engineering practice.The model uses the Fortran to compile the user subroutine of the ABAQUS.The comparison between finite element simulation and experimental results shows that the optimization model proposed in this paper improves the simulation accuracy of finite element software for uniaxial ratcheting behavior,and confirms the success of finite element transplantation of constitutive model.