Safety requirements for cyclists during impacts to the legs

The term vulnerable road user (VRU) is most commonly associated with pedestrians and in particular children and the elderly. In many European countries cyclists make up a significant number of VRU casualties - typically around one third. In the context of the European 6th Framework Integrated Project APROSYS (Advance PROtection SYStems), a study was conducted to examine the safety requirements for cyclists and whether these were addressed by current pedestrian safety assessments of cars. An examination of accident statistics was first conducted to determine the principal accident scenarios for cyclists. Since insufficient cyclist cases were recorded in a detail database of VRU accidents compiled during APROSYS, a programme of virtual testing was then conducted. The objective was to identify the most significant parameters during cyclist impacts with a range of cars sizes and the likely injury consequences. The primary region of investigation was impacts to the legs and knees - the points of first contact. The study indicated that cyclists interacted differently with cars than pedestrians, resulting from the geometric configuration of their legs, the presence of the bicycle and their elevated riding position. The potential for injury was different and the current sub-system impactor tests used by Euro NCAP and for vehicle certification purposes did not address all these differences. It was determined that the relevance of the current pedestrian impact safety assessments of cars for cyclists could be improved by minor changes to the test parameters. However, the study also identified new injury mechanisms that may require further biomechanical investigations. Although this study has considered a wide range of cyclist impact configurations it should not be considered as definitive. Further work including physical testing is needed in order to take forward improved safety test procedures

Étude de la formation de débris d'usure dans la prothèse totale de hanche par un modèle numérique particulaire

La présence de débris d'usure de polyéthylène à haut poids moléculaire (UHMWPE) est une des causes principales du descellement des prothèses totales de hanche. Les travaux expérimentaux de Cooper ont montré de multiples détériorations microscopiques de la surface de la cupule dues à de l'usure par abrasion et adhésion. Les mécanismes de l'usure abrasive sont liés à différents paramètres tels que la charge normale et la vitesse de glissement appliquées mais également de l'angle d'attaque des particules d'usure ou des aspérités microscopiques. Le but de la présente étude est d'analyser l'effet de la géométrie d'une aspérité sur les mécanismes d'abrasion de la surface de la cupule en UHMWPE ainsi que la formation de particules d'usure. Il s'agit de simuler une aspérité rigide glissant sur la surface de la cupule en polyéthylène en utilisant la méthode numérique particulaire appelée « Smoothed Particle Hydrodynamics » (SPH)

The PROMIS model to highlight the importance of the foetus to the validation of a pregnant woman model

The percentage of trauma during pregnancy related to road accident is between 50% and 75%. This type of trauma can result in premature birth or even foetal loss. To analyse and understand the injury mechanisms in pregnant women involved in a car accident, several studies proposed computational or physical tools to simulate accidents. Specific dummy and numerical models have been proposed and validated using experimental data from post-mortem human surrogate (PMHS) scaled with the equal-stress, equal-velocity scaling method to a pregnant woman. This study proposes to evaluate the reliability of this assumption and its scope

Sensitivity and stochastic analysis in a crash simulation environment

Some results of a sensitivity analysis of a car passenger compartment with respect to the driver passive safety response have been reported. The system considered is a sled-test ridge, in which a hybrid III dummy, together with seat and dashboard, has been submitted to the deceleration pulse of a crash test. Attention has been focused on the influence of the knee-bolster foam cushion on some biomechanical damage indexes. The foam is a polypropylene honeycomb type called StrandfoamTM from Dow. The model of its mechanical characteristics is based on the Gibson model [Gibson, L.J. and Ashby, M.F., 1997, Cellular Solid. Structure and Properties (Cambridge University Press).]. The influence of the foam parameters variation was studied, and correlations between the variations of the input parameters and the output responses were investigated. Multivariable statistics analysis and the software ADVISER (Advance and Vites Software for Evaluation and Rating) were used