Development of fast computation algorithm for load transfer Ustar (U*) calculation in structures with slidable supports

Abstract

A parameter Ustar (U*), which is independent of stress or strain, was previously developed by the authors to express load transfer. The connectivity between the loading point and an arbitrary point is represented by U*. The most serious problem encountered while calculating U* using FEM is the high computation time required. For a large-scale model, computation would take several weeks even if a supercomputer is used. To overcome this difficulty, we had previously developed the inspection loading algorithm, which is adopted to several available programs (e.g., Nastran U*Toolkit). However, the previous algorithm is not applicable to structures that have slidable supports due to the complexity of the stiffness modeling contraction. In the present study, the stiffness modeling was exchanged and a new algorithm was introduced. The basic equation was extended to include the previous equation. The computation time reduction is over 90 percent. In usual FEM calculations considering the slidable ends, it is easy to obtain results by removing the degree-of-freedom of the stiffness matrix. Our goal is not there. The purpose of the present study is to develop a fast U* calculation algorithm that can avoid a huge number of iterative FEM calculations. In an actual calculation involving a passenger car body, the results obtained by the new algorithm coincided with the accurate values.