Damage model of bone under mechanical and electromagnetic loadings

Bone, as a living tissue, has an amazing property which is distinctly different from common engineering materials and up to now we have not been able to build into artificial materials: it can repair itself. This renewing process is performed by bone remodeling, but the functions of bone remodeling are far more than repairing the damaged bone tissue. Bone can also adapt its internal microstructure and, subsequently, mechanical properties to the varying mechanical and physiological environments. So the bone damage behavior can be easily influenced by many factors. In the present paper, we establish a mechanism-based damage model to rationalize the damage evolution law of bone under simultaneously applied mechanical and electromagnetic fields. Some crucial physical and biological mechanisms underlying the sophisticated damage, remodeling and healing process of bone tissues have been incorporated in the model. Especially, an evolutionary law of bone damage and the corresponding modeling methodology are presented to analyze the complicated damage/repair behavior of bone under multi-fields. Several representative examples are given to verify the application of the proposed theoretical model in modeling the effects of environmental loadings on bone damage and repair. The results demonstrate that this model can well describe how the bone resists the damage accumulation induced by overloading and how the extreme overloading causes stress fracture of bone. We also study the role which electromagnetic fields play in bone remodeling.