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Bone is a living tissue which constantly undergoes a complex process of adaptation in response to its biochemical and mechanical environment to optimize its resistance to failure. The bone adaptation due to the mechanical loading is dependent on a combination of different mechanical stimuli such as the magnitude and frequency of the applied load, number of cycles, number of bouts, time between bounds, and other factors. In this presentation we discuss the model of adaptation in cortical bone which employs the finite element stress analysis coupled with an evolution law. The finite element model is generated from microcomputed tomography images of the rat ulna and the stress analysis is carried out using boundary and loading conditions on the rat ulna obtained from the experiments of Robling et al. [1]. Initially, we use an elastic material model and a simple growth law with strain energy density as the mechanical stimulus to simulate the effects of the load magnitude and the number of bouts. Then, we include the effect of load induced fluid flow in cortical bone by modeling bone as a poroelastic material. Our analysis focuses on the growth behavior in a rat ulna due to oscillatory loading. We use the dissipation energy based the mechanical stimulus as the triggering stimulus for adaptation using arguments based on the second law of thermodynamics. In the analysis, we account for the hierarchical structure of bone indirectly. Very good agreement is found with the experiments of Robling et al. [1]. REFERENCE [1] Robling et al. JBMR, 2002, 17, 1545.

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Modeling of cortical bone adaptation due to oscillatory loading

Bone is a living tissue which constantly undergoes a complex process of adaptation in response to its biochemical and mechanical environment to optimize its resistance to failure. The bone adaptation due to the mechanical loading is dependent on a combination of different mechanical stimuli such as the magnitude and frequency of the applied load, number of cycles, number of bouts, time between bounds, and other factors. In this presentation we discuss the model of adaptation in cortical bone which employs the finite element stress analysis coupled with an evolution law. The finite element model is generated from microcomputed tomography images of the rat ulna and the stress analysis is carried out using boundary and loading conditions on the rat ulna obtained from the experiments of Robling et al. [1]. Initially, we use an elastic material model and a simple growth law with strain energy density as the mechanical stimulus to simulate the effects of the load magnitude and the number of bouts. Then, we include the effect of load induced fluid flow in cortical bone by modeling bone as a poroelastic material. Our analysis focuses on the growth behavior in a rat ulna due to oscillatory loading. We use the dissipation energy based the mechanical stimulus as the triggering stimulus for adaptation using arguments based on the second law of thermodynamics. In the analysis, we account for the hierarchical structure of bone indirectly. Very good agreement is found with the experiments of Robling et al. [1]. REFERENCE [1] Robling et al. JBMR, 2002, 17, 1545.