Robustness and Reliability of Front Underrun Protection Systems

Abstract: In 2001, the United Nations Economic Commission for Europe decided that all trucksmanufactured as from that year need a front underrun protection system (FUPS).This as a step in order to decrease fatalities in head-on collisions between heavy goodsvehicles (HGV) and passenger cars. A further development of the FUPS is an energyabsorbing FUPS (EA-FUPS). For a safety system like the EA-FUPS it is importantthat its functions work properly in both expected and unexpected crash scenarios.In other words, the system should be robust. In addition to a robust behaviour onewould like to determine the successfulness of the system, i.e., the reliability of thesystem should be evaluated.This Master's Thesis contains a reliability and robustness study of an EA-FUPS,where stochastic analysis of a head-on collision between an HGV and a passengercar has been utilised. In this analysis the probability density functions (PDF:s) ofcollisions and structural parameters have been set up according to statistics fromreal-world accidents and manufacturing data. Several responses from the numerouscrash simulations, solved with an explicit nite element method, were logged andstatistics were used to set up, e.g., probabilities and scatter plots to evaluate thesystem.The results show a FUPS that, although the energy absorbing capabilities arerather non-robust and unreliable, fulls its prime objective, which is protecting thepassenger car from underrunning the HGV. However, when the vehicle overlap issmall the FUPS is not still enough to protect the wheel from being hit. There areseveral reasons for the unreliable energy absorption level, e.g., the energy absorbingmechanism has poor compatibility with the front structure of many passenger cars.Besides the resulting reliability and robustness analyses, an algorithm for performingrobust CAE is presented.