Comparison and implementation of two different out-of-core solvers both with and without efficiency improvement techniques into the CAEFRAME finite element code

Currently, the solution algorithm used to solve the generated set of equilibrium equations in the CAEFRAME finite element code operates only in-core. Even though this in-core solution algorithm is very efficient, it is desirable to replace it with an out-of-core solution algorithm which uses external disk space so that larger problems can be solved.

This thesis describes the necessary modifications which were made to two out-of-core linear equation solvers that were originally written for other computer systems in order to integrate them into the CAEFRAME code. Efficiency improvement techniques specifically tailored to each of the two out-of-core solvers were also incorporated. These modifications resulted in four different out-of-core solver configurations.

Several structural models were analyzed using these solvers. Comparisons were made to ascertain which out-of-core solver configuration should replace the current CAEFRAME in-core solver.

It was determined that the blocked out-of-core solver using the modified Cholesky algorithm in conjuction with a bandwidth reducer offered the best trade-offs of solution runtime, disk storage use and maximum problem size versatility.

However, in order to retain the maximum efficiency in solving both small and large problems, it is recommended that both the current in-core solver and the blocked out-of-core solver each with bandwidth reduction capabilities be incorporated in the CAEFRAME code.