Simulations of test crashes have been carried out using two dimensional and three dimensional models using the MADYMO computer program. These simulations have included seat-belted Hybrid III dummies in the vehicle. Output includes the vehicle acceleration, velocity and force characteristics as well as those of the Hybrid III dummy. Comparison of the MADYMO results with the crash test results shows that the initial model development provides very useful and reliable insight into the performance of the underrun barrier and 'occupant' response. The results also confirmed the significant benefits attainable in terms of occupant protection (significantly reduced vehicle peak deceleration and occupant loading), through the use of energy absorbing rear underrun barriers on heavy vehicles. As with all model development it is also clear that improvements to the vehicle model itself are required, in particular that of the vehicle's front end deformation characteristics (the crash pulse) to ensure more accurate and realistic modelling. The study has enabled the development of expertise in the use of MADYMO as a tool for the analysis and design of crashworthiness systems, and has demonstrated the usefulness of this tool. This type of program does require, however, the commitment of sufficient resources to maintain and strengthen the experience and expertise in its use. (A)
Abstract