quasi-static analysis

Dear all,

 in commercial FE codes, such as ABAQUS, ANSYS, there is option to get convergence in quasi-static analysis by using artificial damping factor. I tried to dig their documentation about this method, but it is somewhat sparse. Could some body recommend me some literature about this topic so that I can gain a better understanding about it.

I thank you in advance.

Sincerely yours,

Ken