ABSTRACT
Pedestrian accidents are one of the main causes of traffic fatalities and injuries worldwide. New pedestrian safety regulations are being proposed in Europe and Japan to improve the protection afforded to pedestrians. Numerical simulations with biofidelic pedestrian models can be used to efficiently assess the risk to injury in pedestrian-vehicle impacts and to optimize the pedestrian protection in the early stages of the vehicle design process at relatively low costs. The goal of this study was to develop and validate a scaleable mid-size male pedestrian model. The model parameters were derived from published data and a large range of impactor tests. The biofidelity of the model has been verified using a range of full pedestrian-vehicle impact tests with a large range in body sizes (16 male, 2 female, height 160-192 cm, weight 53.5-90 kg). The simulation results were objectively correlated to the experimental data. Overall, the model predicted the measured response well. In particular the head kinematics were accurately predicted, indicated by global correlation scores over 90 %. The correlation score for the bumper forces and accelerations of various body parts was lower (47-64 %), which was largely attributed to the limited information available on the vehicle contact characteristics (stiffness, damping, deformation). Also, the effects of the large range in published leg fracture tolerances on the predicted risk to leg fracture by the pedestrian model were analyzed in detail. The validated mid-size male model was scaled to a range of body sizes, including children and females.
ABSTRACT
Recent laboratory investigations suggest that a deploying airbag may fracture the forearm. These studies positioned the arm in an overhand grasp placing the forearm over the airbag module. However, there is little published data on how drivers grip the steering wheel and the general proximity of the upper extremity to the airbag module. The objective of the current study was to identify 'real world' upper extremity positions and to correlate these with accident and experimental data. A survey of the National Automotive Sampling System (NASS) for the years 1995-99 revealed an increase in the number of forearm fractures due to driver-airbag interaction. As NASS does not provide the position of the forearm, common upper extremity positions were identified in a volunteer driving population. These positions were simulated using a specially instrumented 50(th) percentile male dummy to determine the relative injury risk for the different positions. Analysis showed that an under hand grasp of the wheel turned 90 degrees yielded the highest magnitude impact event. This single position was then simulated in 9 cadaver experiments. Dual stage airbag deployments produced forearm fractures in 2 arms. Experiments using the contralateral arms from the fractured subjects with a single stage airbag deployment produced no fractures. Analysis of forearm kinematics suggests that increasing forearm velocity and thus, acceleration exposure, is associated with forearm injury. Further, the data suggests that reductions in acceleration exposure via reduced airbag inflation decreased the apparent risk of forearm fracture.
