Tools for Occupant Protection Analysis

The design of occupant restraint systems in the automotive industry has shifted from an empirical approach to a computer aided analysis approach for many years now. Various finite element software programs have been applied in crash safety analysis, and multi-body dynamics codes have been successfully used where quick system response times were required. Most new vehicle programs are analyzed by the use of finite element tools that were used for previous program projects. Software that has specific occupant protection features may be coupled with these finite element tools, or new vehicle programs may be developed from scratch by using one tool that does all, i.e. a tool where the multi-body dynamics are integrated into the finite element method. Both these approaches will be elaborated as valid tools for occupant protection analysis. At first, the coupling between the finite element crash program LS-DYNA and the F.E./multi-body program MADYMO will be addressed by a frontal impact application. Secondly, this same example will be worked out in the F.E./multi-body program MADYMO only. It will be shown that in case the LS-DYNA vehicle model is already available, the coupling with MADYMO is a very efficient way to get occupant analysis results. The alternative method to work out the vehicle and occupant analysis in one and the same crash code, i.e. MADYMO, has some advantages too. A decision tree as to what method is to be preferred in a specific stage of a vehicle program is suggested. In this way, the crash safety analyst is supported to make the right choice between the various tools for occupant protection analysis.