Elasto-plastic analysis of micro FGM beam basing on mechanism-based strain gradient plasticity theory

Using the consistent thermodynamic formulations, a mixed hardening plastic model based on conventional theory of mechanism-based strain gradient plasticity is built and applied in dynamic analysis of micro-functionally graded material beam. In this mixed kinematic hardening constitutive model, the plastic strain gradient only affects flow stress to reflect size effect as that in the MSG theory [1,2] based on Taylor dislocation model. No higher stress is introduced in present constitutive relations which makes it easy and straightforward to be implemented in a finite element code. By incorporating proposed constitutive model with use of subroutine UMAT in finite element ABQUS basing on implicit stress integration, the static and dynamic analysis on micro FGM beam has been carried out. Two numerical comparisons with experimental results and other numerical results demonstrate the applicability of present constitutive model on prediction of plastic behaviors of materials. In application of present constitutive model in mechanical analysis of micro FGM beam, some numerical examples are carried out for parameters analysis on mechanical properties of micro FGM beam and some useful conclusions have been obtained which are of theoretical significance for engineering application.