Injury Response Analysis Of The Knee Joint To The Pedestrian Impact

Along with vehicle stock of China increasing dramatically, the traffic accidents rising sharply have resulted to increase the casualties every year, especially for the accident of pedestrian in the mixed traffic for China. The injuries of the lower limbs are the main factor of the disabled pedestrian and the loss caused by those is stupendous every year and bring many social problems. The questions of biomechanics especially the injury mechanism and injury criteria of the knee joint being researched and understood by modeling the3D mathematical model of injury biomechanics (the finite element model-FE model) for the pedestrian lower limbs with the detailed anatomy structure, is important method. Then the biomechanics data and theoretical direction are supplied to design the safety of vehicle, and for reducing the damage of pedestrian has more significance of theory and high worth of the practical application.Based the anatomy structure of lower limb, a high biofidelity FE model of lower limb was modeled. Firstly, the interested tissues were extracted from the spiral CT scans of lower limb for the50th Chinese adult male by medical image software of MIMICS, and the geometrical model of tissues were reconstructed with the triangle surface, including tissues of the4th and5th lumbar, sacrum, coccyx, hip bone, femur, patella bone, tibia, fibula and skin of whole lower limb and so on. Secondly, it needed to repair and smooth the initial model from the CT scans via using the reverse engineering software of Geomagic Studio, and generated the CAD model with NURBS (Non-Uniform Rational B-Spline) curve preparing for meshing. Thirdly, Based on the geometrical model, it needed to be meshed and optimized by using the meshing software of Truegrid and Hypermesh, then the whole meshing models of lower limb included hard tissues and soft tissues with the4th and5th lumbar, sacrum, coccyx, hip bone, femur, patella bone, tibia, fibula, meniscus, pubic symphysis, cartilages, intervertebral disc, passive muscle, ligaments, joint capsule and skin and so on. Finally, the whole FE model of lower limb was modeled by setting the boundary condition of simulation tests based on the cadaver tests.Verifying the validation of FE model for lower limb was performed by impacting simulation tests including three-point bending tests of naked tibia FE model and intact leg FE model, the pure shearing and bending tests under the impact velocities of20km/h for the whole lower limb FE model with using the FE analysis software of PAM-CRASH (France, ESI). It can safely draw a conclusion that the simulation results were agreement with the test values, its parameters were consisted of impact force, shearing displacement and bending angle and injury of main ligaments of knee joint. It can indicate that the finite element model of lower limb with high biofidelity was valid, as a calculation model of the injury biomechanics of the lower limb.Application for the FE model of lower limb on the different height frontal bumper of vehicles (325mm for the low one and450mm for high one) was studied under lateral impact to the lower limb at the middle velocity32km/h, and analysis the injury mechanism of lower limb. Then these can supplied the powerful theory to the designing of frontal bumper safety.This research that studying the impact response analysis of lower limb model, mainly the knee joint model can provide a set of methods for further improvement of lower limb FE model and construct full human FE model and establish foundation for studying biomechanics for the human FE model further, and then supply the powerful evident to the designing of vehicle safety.