An improved implicit algorithm for the elastic viscoplastic boundary element method

This paper presents an improved implicit elastic viscoplastic boundary elem ent approach for a general strain hardening model which includes the mixed strain hardening and, as special cases, both the isotropic and kinematic ha rdening. An improved implicit scheme related to different yield functions ( Tresca, von Mises, Mohr-Coulomb, Drucker-Prager, Modified Zienkiewicz-Pande ) is introduced, in which a unified explicit form of the viscoplastic strai n derivative matrix H is developed. As compared with the usual implicit sch eme, in the improved implicit scheme, the viscoplastic strain, rate contain s not only the current stress increment but also the viscoplastic strain in crement. The improved implicit scheme is combined with two boundary element approaches (pure and mixed BEM). Numerical stability related to the improv ed schemes is discussed for the time step length limit. Finally, numerical examples, discussion, and comparison with existing research results are pre sented to illustrate the performance of the improved implicit algorithm.