I am attempting to use non linear - tresca yield criterion with a elastic, perfectly plastic material mode.  Firstly, how do I setup the perfectly plastic material mat'l?  I have tried the following with the solver refusing to converge on a simple, one component beam geometry, where the problem solves easily for linear elastic, isotropic mat'l. mode. 

1. set the the tangent modulus to 0 psi and kinematic hardening ratio to 1

2. enter the (engineering) stress - strain line with first point at yield and second point at elongation (i.e., rupture) in tension only (the loading is logically in tension).

The study is quasi-static non linear with the folllowing settings: time increment is automatic, large strain option only selected, direct sparse solver with force, NR, Newmark settings, loading period is 1 s (default).  I have also attempted to vary the load below and above the yield condition:  no luck even with a low load with the non linear solver!  As I mentioned, this is a very simple geometery/loading problem; What am I, generally, doing wrong?