Computation of stiffness-/damping matrices

Dear all,
with the help of Jason Jonkman I already found that the mass matrix to be solved is computed in the subroutine ElastoDyn.f90/FillAugMat(). Thank you!

Additionally I was told that the stiffness- and damping matrices are only computed during a linearization analysis.
I would appreciate if you also can tell where to find the routines that compute these mentioned matrices. Thank you very much in advance!

Best regards,

Dear Sebastian,

The ElastoDyn routine ElastoDyn.f90/ED_JacobianPContState() computes dX/dx using a central-difference perturbation method, which is the derivative of the state equations with respect to the states i.e. the linear state matrix “A”, which contains 0, I, -[ M^-1 ]*K and -[ M^-1 ]*C as sub block matrices. With knowledge of the mass matrix (M), this matrix can be used to derive the stiffness (K) and damping (C) matrices.

I hope that helps.

Best regards,