Adaptive methods for non-linear finite element analysis of shell structures

摘要

The report deals with the safety of domed structure elements for offshore platforms. It is concerned with methods leading to automated adaptive numerical solutions to geometrically non-linear shell-type problems. In particular, procedures for improving the accuracy, the reliability, and the computational efficiency of the finite element solution are of primary interest. The objective is addressed by considering the four-noded shell element developed by Simo and co-workers, which has been implemented in the non-linear finite element code FENRIS. Special consideration is given to the development of an octant refinement/de-refinement strategy that yields a proper mesh gradation reflecting the computed error distribution in the finite element solution. Another important issue when dealing with adaptive non-linear finite element analysis is the transfer of solution variables between two different finite element meshes. The report describes the solution transfer process in detail for the type of shell elements considered. This includes also a detailed description of a point searching procedure that is needed in order to relate the two meshes to each other. Implementation issues of the adaptive solution procedure are discussed. 113 refs., 57 figs., 6 tabs.