具有层状微观结构的NiTi单晶本构模型

摘要

建立了应力诱发的具有层状微观结构的NiTi单晶本构模型．模型考虑母相和马氏体相弹性各向异性性质的差异，以NiTi单晶相变过程中可能出现的24个马氏体变体为基础，利用相变驱动力和理想界面的连续条件推导了马氏体相变的发生及发展过程，以及单晶相变过程中宏微观应力应变的演化，数值模拟了在不同加载方向材料的应力应变响应．结果表明，对于不同的加载方向，NiTi单晶既存在强化也存在软化现象．%A stress-induced constitutive model of laminated NiTi single crystal was constructed. Based on the laminated microstructure of martensite twins and the difference of the elastic anisotropic properties between austenite and martensite phases, we constructed the model using thermodynamics with perfect interface condition. We also numerically simulated the evolution of micro-stress and strain during phase transformation and the response of stress-strain to the different loading directions. The numerical results show that NiTi single crystal has hardening or softening mechanical properties during transformation according to the different loading directions.