| In road traffic,women with small stature,as a vulnerable group,face a very high risk of injury.The lower extremity are one of the most vulnerable parts in traffic accidents.Therefore,researchers should pay more attention to the safety injury protection of small-stature women’s lower extremity.In recent years,the application of human body finite element model for crash damage research has become an important means of vehicle safety development.For small stature women,several versions of the 5th percentile female human body finite element model with European and American human body sizes have been developed abroad.However,the domestic development of the 5thpercentile female finite element model is mostly based on the scaling of foreign models,which does not conform to the physiological structure of the Chinese human body.In this study,a finite element model of Chinese lower extremity with detailed anatomical structure will be established,which will be used to study the mechanism of lower extremity injury in Chinese small-stature women as a tool.According to the latest measurement statistics of China National Institute of Standardization,to obtain CT image data of Chinese women with small stature.Medical imaging and reverse engineering software were used to extract precise geometric contours of lower extremity.Using the finite element preprocessing software such as Truegrid and Hypermesh for meshing and material attribute assignment.A finite element model of the lower extremity of Chinese 5thpercentile female pedestrians with detailed anatomical structural features was constructed.The model includes all bones,muscles,fat,skin and connective tissues.The total mass of the model is 18.8 kg.It is composed of 80 parts,with a total of 63514 nodes,43791 solid elements and 21922 shell elements.The finite element model of pedestrian lower extremity was validated by reconstructing several cadaver tests,including static three-point bending corpse experiments,dynamic three-point bending corpse experiments,and knee joint lateral bending and shearing cadaver experiments at high speed.The verification idea is from the part to the whole.These curves from the simulation tests were all in the corridors form the cadaver tests,such as the force-displacement curve,moment-displacement curve,the curve with time of impact force,knee bending angle and shear displacement.These indicated that the developed model has good biofidelity.Based on the verified 5th percentile female pedestrian lower extremity finite element model,a simulation study of lower extremity injuries in human-vehicle was carried out using four vehicle types recommended in the E-NCAP regulations.The right side of the finite element model is collided by FCR（Family car）,MPV（Multi-Purpose Vehicle and Superminis）,RDS（Roadsters）and SUV（Sport Utility Vehicle）.The speed is set to 30km/h,40km/h,50km/h respectively.The simulation results show that the speed affects the moment of lower extremity injury.The higher the speed,the earlier the injury occurs.On the impact side,the medial collateral ligament was most likely to tear,and on the opposing impact side,the lateral collateral ligament and posterior cruciate ligament（PCL）were most likely to get injured;ligament damage was most severe at 50 km/h.The height of the vehicle types above or below the height of the extremity can lead to different injury conditions in the femur,with less impact on the tibia and fibula.Only proximal femoral fractures were observed in the SUV model accident,while the remaining three vehicle types showed fractures of the femoral stem,proximal end,and distal end.The research results provide basic data for the analysis of vehicle-pedestrian lower extremity crash damage,and have important application value for pedestrian lower extremity protection and injury assessment. |
