By adding copper to increase the performance,the Ni-Ti-Cu Shape Memory Alloy(SMA),has been widely used in the field of engineering in recent years.A thermodynamic constitutive model for Ni-Ti-Cu SMA considering differ...By adding copper to increase the performance,the Ni-Ti-Cu Shape Memory Alloy(SMA),has been widely used in the field of engineering in recent years.A thermodynamic constitutive model for Ni-Ti-Cu SMA considering different copper contents is established in this work.Numerical results for two different copper contents,as examples,are compared with the experimental results to verify the accuracy of the theoretical work.Based on the verified constitutive model,the effects of different copper content on the mechanical properties of Ni-Ti-Cu SMA and the tensile and compressive asymmetric properties of Ni-Ti-Cu SMA are finally discussed,respectively.展开更多
An analytical solution is obtained for the Functionally Graded Shape Memory Alloy （FG-SMA） composites subjected to thermo-mechanical coupling. Young＇s modulus and thermal expansion coefficient of the material are a...An analytical solution is obtained for the Functionally Graded Shape Memory Alloy （FG-SMA） composites subjected to thermo-mechanical coupling. Young＇s modulus and thermal expansion coefficient of the material are assumed to vary in different forms of power function through the thickness, with the Poisson＇s ratio being constant. An SMA constitutive model is combined with the averaging techniques of composite to determine the mechanical properties of the FG-SMA composites. Different phase transformation steps and the corresponding stress distributions through the thickness direction are given. The results show that the average stresses decrease as the transformations proceed.展开更多
For better controllability in actuations,it is desirable to create Functionally Graded Shape Memory Alloys（FG-SMAs）in the actuation direction.It can be achieved by applying different heat treatment processes to crea...For better controllability in actuations,it is desirable to create Functionally Graded Shape Memory Alloys（FG-SMAs）in the actuation direction.It can be achieved by applying different heat treatment processes to create the gradient along the radius of a SMA cylinder.Analytical solutions are derived to predict the macroscopic behaviors of such a functionally graded SMA cylinder.The Tresca yield criterion and linear hardening are used to describe the different phase transformations with different gradient parameters.The numerical results for an example of the model exhibit different pseudo-elastic behaviors from the non-gradient case,as well as a variational hysteresis loop for the transformation,providing a mechanism for easy actuation control.When the gradient disappears,the model can degenerate to the non-gradient case.展开更多
基金support by National Natural Science Foundation of China(No.11502284)Key Deployment Projects of the Chinese Academy of Sciences(KFZD-SW-435)the Fundamental Research Funds for the Central Universities of China(3122020077).
文摘By adding copper to increase the performance,the Ni-Ti-Cu Shape Memory Alloy(SMA),has been widely used in the field of engineering in recent years.A thermodynamic constitutive model for Ni-Ti-Cu SMA considering different copper contents is established in this work.Numerical results for two different copper contents,as examples,are compared with the experimental results to verify the accuracy of the theoretical work.Based on the verified constitutive model,the effects of different copper content on the mechanical properties of Ni-Ti-Cu SMA and the tensile and compressive asymmetric properties of Ni-Ti-Cu SMA are finally discussed,respectively.
基金Project supported by the National Natural Science Foundation of China(No.11502284)the Tianjin Natural Science Foundation(No.15JCQNJC42600)+1 种基金the Fundamental Research Funds for the Central Universities of China(No.3122014C015)the open fund of the airport project(No.JCGC2015KFJJ005)
文摘An analytical solution is obtained for the Functionally Graded Shape Memory Alloy （FG-SMA） composites subjected to thermo-mechanical coupling. Young＇s modulus and thermal expansion coefficient of the material are assumed to vary in different forms of power function through the thickness, with the Poisson＇s ratio being constant. An SMA constitutive model is combined with the averaging techniques of composite to determine the mechanical properties of the FG-SMA composites. Different phase transformation steps and the corresponding stress distributions through the thickness direction are given. The results show that the average stresses decrease as the transformations proceed.
基金the financial support of National Natural Science Foundation of China (no.11502284, 51505483, 11772041)the Fundamental Research Funds for the Central Universities (3122016C006) of China
文摘For better controllability in actuations,it is desirable to create Functionally Graded Shape Memory Alloys（FG-SMAs）in the actuation direction.It can be achieved by applying different heat treatment processes to create the gradient along the radius of a SMA cylinder.Analytical solutions are derived to predict the macroscopic behaviors of such a functionally graded SMA cylinder.The Tresca yield criterion and linear hardening are used to describe the different phase transformations with different gradient parameters.The numerical results for an example of the model exhibit different pseudo-elastic behaviors from the non-gradient case,as well as a variational hysteresis loop for the transformation,providing a mechanism for easy actuation control.When the gradient disappears,the model can degenerate to the non-gradient case.
