The solution of this problem must be preceded by the calculation of element stiffness matrices $\mathbf{K}$ (i.e., the first three steps of the linear elastostatic problem solution). The following conditions apply:

• The same elements can be used as in linear elastostatics.
• Analytical prescription of symmetry or periodicity cannot be used.

The right-hand side does not matter in this case; therefore, only quantities specifying material properties and displacement boundary conditions can be considered in the first load case (AS 1) in the name.i2 file.

Input data are written to the text file name.iM. The program generates consistent (thus positive-definite) mass matrices $\mathbf{M}$ of elements.

Input data are written to the text file name.iR. The program factorizes the matrix $$\sum(\mathbf{K}+a_0\mathbf{M}+a_1\mathbf{C}),$$ where $\sum(\dots)$ denotes global (not element) matrices. The consistent mass matrix $\sum(\mathbf{M})$ is positive definite, and the matrix $\sum(a_0\mathbf{M}+a_1\mathbf{C})$ usually exhibits the same property. Since quasi-static processes are not considered here, the matrix $\sum(\mathbf{K}+a_0\mathbf{M}+a_1\mathbf{C})$ will then also be positive definite, even if $\sum(\mathbf{K})$ is only positive semidefinite. It is recommended to check that no pivots smaller than $\mathtt{PIVOT}$ are reported in the name.oR file.

Input data are written to the text file name.i5, where the problem type key is $\mathtt{KPROB}=1$.