Parallel Numerical Procedures for the Solution of Contact-Impact Problems
2000 (English)Doctoral thesis, monograph (Other academic)
Abstract [en]
Finite element (FE) simulations of complex problems tend to yield very large models if detailed knowledge of the problem is required. As the model becomes larger, the time needed for solving the problem increases. The solution time is even longer if contact is present in the model. In order to achieve results within a reasonable time frame, High Performance Computers (HPC) are used. Current HPC are often of a parallel type, and to be utilised efficiently they need parallel algorithms.
In this thesis an efficient parallel contact algorithm for explicit FE simulations is presented. The contact searching is based on a hierarchical concept where also velocity information about the objects is considered. An augmented Lagrangemultiplier method is used to enforce the impenetrability constraints. The parallel algorithm is based on the so-called HITA-DENA algorithm and it is implemented for use in the general FE program mpp/LS-DYNA.
The parallelisation of an FE method using explicit time integration comes mainly from a domain decomposition of the problem. As the solution is carried out, each processor has to communicate certain information to other processors. The objective of most domain decomposition methods is to reduce the fictitious interior border length, i.e. the cut size. We have shown that this criterion is not necessarily the best for a general problem when contact is present in the calculations. Contacts may easily destroy the communication pattern, leading to an increased cost for communication, and decreased performance of the algorithm. In order to increase the efficiency, two separate domain decompositions are proposed: A static decomposition is constructed to give a good load balance for most element-related calculations, while a dynamic decomposition includes only contact information. The redecomposition of the domain for contact calculations is performed regularly with a newly developed parallel Recursive Coordinate Bisection (pRCB) method.
The presented algorithms are general, they can handle complex contact situations, and they have shown good efficiency on several problems.
Place, publisher, year, edition, pages
Linköping: Linköping University , 2000. , p. 206
Series
Linköping Studies in Science and Technology. Dissertations, ISSN 0345-7524 ; 620
National Category
Computer Sciences Computational Mathematics
Identifiers
URN: urn:nbn:se:liu:diva-184184Libris ID: 7624473ISBN: 9172196637 (print)OAI: oai:DiVA.org:liu-184184DiVA, id: diva2:1650245
Public defence
2000-03-02, hus A, ing. 15, Linköpings universitet, Linköping, 10:15
Opponent
2022-04-062022-04-062022-04-06Bibliographically approved