Application of Multirank Lamination Theory to the Simulation of Phase Transformation in Shape Memory Alloys

• Main Authors: Yung-Cheng Tseng, 曾永承
• Other Authors: 舒貽忠
• Format: Others
• Language: zh-TW
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/99264846044954390908

碩士 === 國立臺灣大學 === 應用力學研究所 === 100 === Instead of choosing phenomenological models to describe thermoelastic martensitic phase transformation, the thesis develops a model based on multirank laminated microstructure to study it. Suppose the high temperature phase has a cubic symmetry and the low temperature phase possesses a tetragonal symmetry. A cubic-to-tetragonal solid-to-solid phase transformation is proposed to demonstrate this model. Here, the austenite phase alternates periodically with the martensite phase which consists of compatible tiny banded microstructure. The local volume fractions of low rank structure are used to describe different symmetry related variants and their magnitudes vary at the emerging of new phases. The evolution of variants is simulated under stress/strain/temperature control, and the results are qualitatively in agreement with experimental observations. For example, either stress or strain control will result in no permanent deformation at the removal of loads, giving rise to pseudoelastic behavior. In addition, at low temperature, the deformed martensitic material will recover its original shape when it is heated above the transformation temperature, giving rise to shape-memory behavior. Finally, the simulations results show that strain incompatibility plays an important role on the width of hysteresis. It grows as the incompatibility effect is enhanced.