Injury Analysis And Protection Countermeasure Of Occupant Pelvis During Vehicle Side Impact

The pelvis is one of the most likely affected areas of the human body in side impact. Studying pelvis injury mechanisms in side impact can help to understand the cause and effect of biomechanical relationship. The study results can be used to design countermeasures for restraint system devices to improve occupant safety. This thesis modified a previous three-dimensional 50th percentile finite element model of female pelvis to improve model biofidelity by adding detailed muscles to the pelvis. Side impact simulations were carried out; pelvis injury mechanisms were studied through parametric analysis.The main contents include:1. Based on CT imagines of female pelvis, main muscle structure is extracted by using the threshold segmentation method. The 50th 3D finite element model of female pelvis was created based on reverse engineering principle and FE meshing techniques. This model contains pelvic bones, main muscles, cartilage, skin, fat and the pelvic cavity viscera which are filled with soft tissues.2. Connect muscle model with existing bone model based on anatomical structures, add ligament and fill soft tissue. Abdominal organs were simulated with filled block, and connect pelvic model with lower limb, including muscle, bone, skin, soft tissue.3. Determining the material parameters, defining contact as well as the applied load to the separate pelvis, testing the validity of the model by comparing simulation results with that of cadaver experiments. Fracture threshold was established by applying lateral loads of 1000 N,2000 N,3000 N,4000 N and 5000 N, respectively to the articular surface of the right acetabulum.4. Applying different impact velocities of 3 m/s,4 m/s and 5 m/s, respectively to the articular surface of the right acetabulum. Compare the contact force between the impact block and acetabulum under different impact velocities. It found that impact force increase with impact velocity. The higher the velocities, the higher the chance of fracture occur. It found that hanging door filler material to buffer vehicle collision and reducing the impact velocity can lower the chance of pelvic fracture.5. Compared the response of pelvis with and without muscles in side impact, it found that the muscles and soft tissue play a role of buffering in side collision. It found that pubic rami, ischium, iliac ridge and acetabulum were more easily to be injured where stress concentration was more easily to be found. Through the install of door bumper and airbags can effectively reduce the impact force and speed, then can reduce pelvic fractures.