PRECONDITIONED CONJUGATE-GRADIENT METHODS FOR 3-DIMENSIONAL LINEAR ELASTICITY

Finite element modelling of three-dimensional elasticity problems give rise to large sparse matrices. Various preconditioning methods are developed for use in preconditioned conjugate gradient iterative solution techniques. Incomplete factorizations based on levels of fill, drop tolerance, and a two-level hierarchical basis are developed. Various techniques for ensuring that the incomplete factors have positive pivots are presented. Computational tests are carried out for problems generated using unstructured tetrahedral meshes. Quadratic basis functions are used. The performance of the iterative methods is compared to a standard direct sparse matrix solver. Problems with up to 70000 degrees of freedom and small (much less than 1) element aspect ratio are considered.