I'm recently very interested in computational nolinearity. Would you like recommend some monographs on the computation nonlinearity so that i can have a better understanding of the mechanism of ABAQUS.
For understanding the basic of non-linear FEA you can study chapter 6 of professor Bathe's great book "Finite element procedures". You can also watch his video lectures on non-linear FEA, they are great. For materially non-linear only problems which is the subject of the theory of plasticity, first stuy "Plasticity for structural engineers" by W.F Chen in order to understand the principles, and then in order to have some insight into the computational aspect of plasticity study "Computational Methods in Elasticity and Plasticity " by professor A. Anandarajah, and the great book by J. Simo and Tom Hughes "Computational Inelasticity".
lately I am also really concerned on computational
plasticity. I have read the book introduction to computational
plasticity of Prof.Fionne Dunne, and think it is really comprehensive,
especially you can download the umat subroutines for Abaqus from the
author's website. In my opinion, it is a great book!
By the way, do you know any orthotropic plasticity model which is stress ratio dependent? I have been looking for this kind of model for weeks, but I cannot find any. If any one of you know, please kindly let me know.
I thank you in advance.