why change in friction stiffness creates sliding of leg? and what exactly is happening when iterations keep on running.what do u exactly mean by non-convergence of iteration.

why does it iterate? are there too many unknowns in the equation it generates?

do a search of this forum on "friction" your answer lays within

... and this is a great thread discussing convergence issues.

You'll also find a good discussion on "Friction" in the Technical Reference Manual. This also discusses the <i>Friction Stiffness Setting".

Jayan,

If you want to learn this subject throughly, I would advise you to read book titled " Finite Element Procedures" by Klaus Jurgen Bathe, particlularly the chapter on solution of equations.This study will help you clear your concepts on " convergence", "non linear solutions" etc.

Regards