A Studuy On Helmet Protective Performance For Head Injury Based On Motorcycle Accident Reconstruction

With rapid development of economy in China, the two-wheel-motorcycle has become themost popular way to travel for urban and rural residents. The mixed traffic increased theproperbility of motorcycle accident. The statistics of road traffic accident of the People’sRepublic of China from2000to2008shows that motorcycle accidents caused about18,000to21,000fatalities every year. It accounted for15.8-21%of the total road traffic fatalities andthe number of the motorcyclist fatalities is keeping rising. Riders always get injured or deaddue to the head impacts in accidents. The use of helmet can prevent the head injury from thecrash accidents, but the problems with quality of the helmet and the low rate of helmetwering still brought a threat to the riders safety. Thus this research was carried out toinvestigate the dynamic response of head and the helmet protective performance，which helpswith development of safer helmet to decrease the risk of head injury.In traffic safety research, a deep understanding of the cause and mechanisms ofmotorcycle accidents is dependent to an in-depth investigation by using comprehensive,detailed, real traffic accident data. The author has participated in an accident research team inChangsha and Foshan. It was found that the riders’ head is injured frequently byanalyzing the colleted data of car-to-motorcycle collisions.First, based on the comprehensive understanding of the characteristic of motorcycleaccidents, head trauma biomechanics and head injury evaluation standards,10typicalmotorcycle-car accidents were selected and reconstructed. The MB models of themotorcycle and car were developed by using MADYMO and PC-CRASH for simulations ofthe accidents. Second, a real motorcycle helmet was modeled, especially on the failuremechanism and constitutive model of material of the composite. The helmet was validated viaECE R22.4regulation. Third, a human head FE model and a windshield model developed inHunan University were used to simulate head windscreen impact. The riders’ head injurymechanism was analyzed. At last, another twelve simulations were conducted underhelmeted-head condition. The protective performance and efficiency were analyzed in termsof head injury parameters. The design parameters of the helmet were optimized by using theadvanced DOE method and algorithm. The optimization target was set to head injuryparameter such as the HIC, von Mises stress, Pressure, Shear stress. The injury value wasdecreased after optimization and the protection efficiency was improved.MB reconstruction of car-to-motorcycle collision shows that the head impact velocitywas positively correlated with the car impact velocity. The coefficient is0.882. The motorcycle crash velocity was negatively correlated with the speed of head impact. FEreconstruction head-to-windscreen collision shows that the results of the head injuryparameters match well with the observed injuries in real accidents. In helmeted–headcondition, the protect efficiency was promoted under high impact velocity, but the von Misesstress and Shearstress havn’t improved prominently. In low speed impact situation, the helmetmay become another cause of injuries. The optimized helmet enhanced the protectiveperformance by lowering14.1%on intracranial pressure,28%on counter intracranial pressure,5.7%on von Mises stress and shear stress, and19.6%on HIC. The improved helmet couldprovide background knowledge in helmet design.