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This paper contains a review of current information on biological structure, material properties and failure characteristics of bone, articular cartilage, ligament and tendon. The load-deformation response of biological tissues is presented with particular reference to the microstructure of the material. Although many of the tissues have been characterized as linear, elastic and isotropic materials, they actually have a more complicated response to load, which includes stiffening with increasing strain, inelastic yield, and strain rate sensitivity. Failure of compact and cancellous bone depends on the rate, type, and direction of loading. Soft biological tissues are vlscoelastie and exhibit a higher load tolerance with an increasing rate of loading. The paper includes a discussion on the basic principles of biomechanics and emphasizes material properties and failure characteristics of biological tissues subjected to impact loading.

This paper refines the methodology presented in the companion paper linking reductions in biomechanical responses due to force-limiting material to projections of injury-mitigation in real-world side impact crashes. The revised approach was used to evaluate the potential injury reducing benefit for the chest and abdomen with either constant crush force or constant stiffness, crushable material in the side door and armrest. Using a simulation of the human impact response, a range in crush force or stiffness was determined which reduced the viscous response from that obtained with a rigid impact. NCSS field accident data for car-to-car side impacts provided information on the occupant exposure and injury as a function of the change in velocity (ΔV) of the struck vehicle. Since the velocity of the side door at contact with the occupant's chest is similar to the ΔV of the struck vehicle, the chest impact velocity in the simulation was assumed equal to the observed ΔV in the NCSS data.

This paper presents a methodology to link reductions in biomechanical responses due to force-limiting material to projections of injury mitigation in real-world side impact crashes, and to use this approach to evaluate the potential injury reducing benefit for the chest and abdomen of constant crush force material in the side door and armrest. Using a simulation of the human impact response, a range in crush force was determined which effectively reduced a peak biomechanical response from that obtained with a rigid impact. The range in constant crush force depended on the velocity of impact. The higher the velocity of impact, the higher the level of crush force to achieve a reduction in the peak response. NCSS field accident data for car-to-car side impacts provided information on the occupant exposure and injury as a function of the change in velocity (ΔV) of the struck vehicle.