Research On Mechanical Behavior Of Shape Memory Alloy Beam

Shape memory alloy gets widespread attention because of its shape memory effect and superelasticity features,which have a close relationship with the phase change of shape memory alloy.So,it is particularly important to research the phase change process of shape memory alloy.T his paper researches bending deformation of shape memory alloy beam under the mechanical loads and the thermal-mechanical loads,and studies bending deformation of functionally graded shape memory alloy beam under the thermal-mechanical loads.T he main researching results and conclusions are summarized as follows:The first,basing on the bending deformation theory of beams and combining with the stress-strain relation of shape memory alloy material,it studied the influence of tension-compression asymmetry of shape memory alloy beam on its bending deformation.T he expression of distribution of beam cross section stress and martensitic volume fraction and the nonlinear controlling equation of shape memory alloy beam are obtained.T he influence of tension compression asymmetry coefficient on deflection,curvature and cross section stress,neutral axis,phase boundary,martensite volume fraction,phase transition area are obtained by numerical calculation.At the same time,the influence of the tension compression asymmetry coefficient on the deflection,curvature and cross section neutral axis and phase boundary of different cross-section beams are obtained by numerical calculation,and the comparative analysis are carried out.Next,combining with the critical stress-temperature relationship and stress-strain relationship of shape memory alloy,it studied the influence of tension compression asymmetry coefficient on shape memory alloy beam under thermal and mechanical loads.The relationship between the stress distribution and the tension compression asymmetry coefficient and temperature are obtained,and the nonlinear controlling equation of shape memory alloy beam is obtained too.The calculated results match with the releva nt literatures.T he influence of tensi on compression asymmetry coefficient and temperature on deflection,curvature and cross section stress,neutral axis,phase boundary,martensite volume fraction,phase transition area are obtained by numerical calculation.Finally,the calculation results of shape memory alloy beam and the calculation results of ordinary elastic material beam are compared and analyzed.Finally,combining with the critical stress-temperature relationship and stress-strain relationship of shape memory alloy,and thinking about the macroscopic constitutive model used to description functionally graded shape memory alloy mechanical behavior,it researched the mechanical behavior of functional ly graded shape memory alloy beam under thermal and mechanical loads.T he split-step method is adopted to analyze the process of shape memory alloy phase transformation in the loading process.The relationship between the stress distribution and the tension compression asymmetry coefficient,temperature and power exponent are obtained,and the nonlinear controlling equation of shape memory alloy beam are obtained too.The influence of tension compression asymmetry coefficient,temperature and power exponent on deflection,curvature and cross section stress,neutral axis and phase boundary are obtained by numerical calculation.The conclusion of this paper has a positive role in promoting for the use of bending deformation characteristics of shape memory alloy materials in engineering practice.