Understanding bone strength and fracture by multiscale modeling, testing and imaging: the role of chemical composition and hierarchical structure

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My research program is to study bone strength and fracture by multiscale computational modeling, mechanical testing and imaging. Bone fracture is determined by bone strength and the applied force, and bone strength is in turn determined by bone chemical composition and architecture. Bone has complicated chemical compositions and hierarchical nano-micro-structures. With the existing theories and models established from previous studies that were mostly conducted at macroscale using whole bones or bone specimens, we still do not know how bone strength at macroscale are quantitatively affected by chemical compositions and nano-micro-structures, and how an impact force causes a fracture at a specific site of a bone. To better understand bone strength and fracture, one has to understand the hierarchical architecture of this fascinating material at the molecular, cellular, tissue, organ, and whole body levels, in conjunction with an understanding of the mechanical environment surrounding the body. It is still a long way for biomechanical and biomedical researchers to go. Multiscale modeling is a promising method to understand bone mechanical behavior, but it is still under development. The long-term objective of my research program is to contribute to the establishment of multiscale theories and models for bone strength and fracture. In my previous Discovery Grant (DG) term, I developed a hierarchy of three-level biomechanical models at macroscale to understand the biomechanics involved in fall-induced hip fracture. The short-term objective of my next DG term is to study bone strength and fracture at smaller length scales, i.e. to understand how bone chemical composition (mineral, organic matter and water) and nano-micro-structure (pores and crystal sizes) affect bone strength and fracture. The proposed research will contribute to: (1) the establishment of relationships between bone stiffness/strength and chemical compositions/structures across different scales; (2) the development of multiscale biomechanical models of bone strength and fracture. ***The proposed research would have a major impact on the communities of Biomechanical/Biomedical Engineering and Materials Engineering. For example, the multiscale models of bone strength and fracture would help biomechanical engineers improve the effectiveness of protective devices in manned vehicles. The relationships between bone stiffness/strength and chemical compositions/structures would help biomedical engineers improve evaluation of fracture risk and advance design of 3D printed bone crafts; it would also inspire material engineers to design novel and efficient composite materials. Highly qualified personnel trained in the proposed research would be equipped with cutting-edge knowledge and techniques of material multiscale modeling, which will be necessary for innovations in both Biomechanical/Biomedical and Materials Engineering.**