Influence Of Human Body Size And Mass On Lower Limb Injury Parameters

Lower extremities are the one of most vulnerable parts of pedestrian invehicle-pedestrian traffic accidents. At present, the pedestrian safetyregulations by EC78/2009(European Community-No78/2009) and GTR9(Global Technical Regulation-No.9) are the major requirements ofpedestrian protection from vehicle collisions. A ifxed mass and length oflegform impactor is applied to evaluate the protective performance forreduction of risk of lower limb injuries in these regulations. In the realworld, the pedestrian’s body characteristics, such as height and weight, aresignificantly different.In the existing regulations, the relavant parametersof lower extremity injuries are measured from the sub-system test, and theeffect of the Upper Body Mass (UBM) on the movement and injury of lowerlimbs was not considered.Therefore there exist certain limitations in thepresent regulations for measuring of the injury parameters of lowerextremities.The main purpose of this paper is to analyze the influence of human bodysize (height and weight) on the lower limb injury parameters as well as theeffect of the upper body mass on the evaluation of lower extremity injuryvia legform impactor.So expected results rfom this study can provide areference for improvements of the legform impactor and the pedestrianregulations.In current study, three typical car models and three different percentilepedestrian models were established using multi-body dynamics method.Then the influence of pedestrian weight and height on lower limbs injurieswere thoroughly investigated by comparing the tibia acceleration, sheardisplacement and bending angle of the knee. The results showed that theinfluence of human body size on lower limbs injuries is significant, certainrules of the effect were found as follows: The maximum knee sheardisplacement rose up as the height and weight of pedestrian modelsincreased. While the knee bending angle was greatly affected by thecollision location of the vehicle to pedestrian, The collision position wascloser to the knee joint, the greater the bending angle. The maximum tibiaacceleration illustrated different variation tendency with the change ofvehicle front structure. To study the effect of the upper body mass on the evaluation of lowerextremity injury via legform impactor, the paper ifrstly investigated thebiological ifdelity of TRL LFI (Lower LegForm Impactor) by comparingthe lower extremity injury parameters between the TRL LFI and the ifniteelement model.The crash simulation model was established by using thesame car model and with the increased mass in the upper end of theTRLLFI model. The dynamic response and injury parameters wereanalyzed in terms of results rfom the lower limbs of the TRL-LFI model，theifnite element model and the TRL LFI model with different Upper BodyMass. The effect of the upper body mass on the evaluation of lowerextremity injury via impactor was studied in this thesis. The results showedthat the effects of the upper body mass on the tibia acceleration and kneeshear displacement were not significant, while the influence on the bendingangle of the knee joint was more obvious. With the increased upper bodymass, the peak of the bending angle rose up, which up to9.64When theupper body mass exceeded10kg，the influence on the bending angle showedsmall changes.