Non-convergence because of excessive distortion 1

[soildynamics]

My model does not converge because of (I think) excessive
distortion. Below is what I get from the msg.file
Please advise me how can I overcome this issue

EQUILIBRIUM ITERATION 2

AVERAGE FORCE 1.642E+05 TIME AVG. FORCE 1.642E+05

LARGEST RESIDUAL FORCE -1.283E+04 AT NODE 3864 DOF 2

LARGEST INCREMENT OF DISP. -0.273 AT NODE 8302 DOF 2

LARGEST CORRECTION TO DISP.0.128 AT NODE 8302 DOF 2

FORCE EQUILIBRIUM NOT ACHIEVED WITHIN TOLERANCE.

 

[xerf]

Try decreasing the initial, minimum and maximum time increments.

 

[soildynamics]

Playing with the initial, minimum and maximum time increments couldnot solve the issue.
I am puzzeled about what the solver does when getting non-positive definite matrix (negative or zero stiffness matrix determinate) that could arise , for example, due to material softening/failure. Keep aside the technique used in Riks Step as I can not use this step.

Here is some warning massege I am getting during the job run
"The plasticity/creep/connector friction algorithm did not converge at 1 points

Program is asked to invert a singular matrix"