Geometrical Modeling And Validation Of Long Bones For Lower Limb Based On China’s Human Characteristics

In the field of automotive crash safety, the human body model based on the theory of human body crash biomechanics is an important tool for the evaluation of human body injury. The human body model includes mainly crash dummy model and human body numerical model. Because of the lack of biofidelity and its applicability of certain specific crash scenarios, the crash dummy cannot accurately and truly predict human body injury and has its limitations for the application. The human body numerical model contains tissues and organs such as human bones, muscle, ligament, etc. with high biofidelity and is able to predict human body injury better. With the development of computer performance and accumulation of biomechanical data, the human body numerical model for evaluation of human body injury is being used more and more widely.Based on a large amount of data statistics of human body characteristics and accumulation of crash biomechanical experiments, nowadays the developed countries in Europe and America have successively developed a series of human body numerical models, established standards for injury limits based on human body characteristics of Western as well as issued different kinds of automotive crash regulations. However, since there exist large differences between the human body numerical model based on human body characteristics of Western and Eastern in term of geometrical dimensions and biomechanical parameters, the current human body numerical model is not completely applicable for the design of automotive safety of our country, and there is still no research on the development of human body numerical model based on China’s human body characteristics. Therefore, it is of great significance to develop human body numerical model based on China’s human body characteristics.The present thesis focuses on the lower limb of human body based on China’s human characteristics, builds 3D numerical model for the lower limb of human body by integration of subject knowledge of human body crash biomechanics, image processing of medical imageology, finite element modeling, simulation analysis, etc., as well as conducts the validation of long bones of lower limb, namely femur, tibia and fibula, by quasi static three point bending test. The present project collects the crucial human body dimensions including height, weight, etc. of China’s adult male 50 percentile in cooperation with China National Institute of Standardization. By this dimensional standard a full-body CT scan with 0.625 mm interlayer spacing is conducted on a healthy volunteer in cooperation with Third Military Medical University, of which the slicing images are saved in form of DICOM. The point clouds of femur, tibia, fibula, patella as well as outer layer of skin of the lower limb are exported via the medical image processing software called Mimics. The thesis conducts reverse 3D geometric modeling based on the point clouds by the software CATIA and 3D meshing by the software HyperMesh. The materials and properties of the finite element models of the long bones of lower limb are defined by reference to THUMS human body numerical model and the long bones of lower limb are validated by anteroposterior and lateromedial quasi static three point bending test by referencing Yamada biomechanical experiments.The peak value and overall trend of load-deflection curves of the simulation results and those of Yamada biomechanical experiments match with each other quite well, which indicates that the built finite element models of long bones of lower limb possess good biofidelity.