Vulnerable Road Users. Numerical and Experimental Reconstruction of Cyclist Accidents in Urban Areas

Most cycling accidents occur in urban areas and involve car collisions. In an attempt to define a Finite Element (FE) model of cyclist and bike that can correctly replicate the accident scenario, a numerical experimental analysis has been conducted. The numerical reconstruction is validated by means of results comparison and correlation with experimental tests. A FE bike model has been developed and verified. The available Hybrid III FE model has been modified with respect to its posture to combine it with the bike model previously defined. The whole bike and dummy model has been analysed in actual accident scenarios. The scenarios analysed differ in bike-car angle, velocity, car vehicle model. The focus has been on cyclist injuries: typology and severity. The results of the research intended to define injury threshold levels and the differences in injuries with and without protective garments, in addition with the definition of a reliable bike-dummy numerical model. A series of car-bike impacts was simulated using the bike FE model and combined with the Hybrid III FE model. The numerical simulations have been performed in LS-DYNA FE solver, which gave the possibility to reproduce crash impact scenario. The bike FE model has been created in Hypermesh and imported in LS-DYNA, where analysis have been conducted to validate the model. In the simulations, impact velocity, bike-car angle and vehicle model were varied. The performance of the model was assessed comparing the experimental test performed at La.S.T. (Laboratory of Transport Safety) at Politecnico di Milano under comparable conditions. The Hybrid III Anthropomorphic Test Device has been instrumented as needed (head accelerometers, neck load cells, chest accelerometers, chest deflection transducers, femur force transducers). It has been tied to a city bike model, selected on the base of urban accident database. The research is funded by ASAIS EVU Italia. Keywords: Vulnerable road users, Cyclist accident, Head Injury, Brain Injury, Hybrid III, LS-DYNA