ABSTRACT In order to treat scoliosis, a thermo-mechanical behavior study of shape memory alloy bone staple has been proposed. A pre-stretched shape-memory-alloy bone staple, which has been heated above the transition temperature, provides greater compressive force upon insertion between two vertebrae and allows the control of idiopathic scoliosis development. Until now, the optimal design has not been reached due to the lack of appropriate design tools for shape memory alloy devices. In this paper, a shape memory alloy bone staple model is proposed by developing a user subroutine UMAT based on Boyd et al. unified thermodynamic shape memory alloy constitutive law using the finite element analysis software, ABAQUS. The numerical results for superelastic and shape memory effect under the tensile and three-point bending tests are presented. Simulations of the shape memory effects and force generation of the shape memory alloy staple are also shown.
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