CentralDifference algorithm

[keqiliu]

Dear Frank and users,

I want to use "Central Difference integrator" to analyze nonlinear quesions in OpenSees.

We konw, for elastic question, the material tangent is constant, and we only need compute the tangent only once if we use "Central Difference integrator".

But if we want to analyze the nonlinear questions, the material tangent is always changing, do the "Central Difference integrator" need compute the current tangent?

[fmk]

not with constant mass and if use initial stiffness terms in the damping matrix. it does not appear in the tangent which is a function of mass and damping matrix.