Micromechanical Testing and Multivariant Model Correlation for Shape Memory Alloys

用扫描电子显微镜和背散射电子衍射仪研究形状记忆合金(SMA)在单轴和多轴载荷下的响应。这些实验将提供在不同加载条件下变体演化的详细信息，并将与PI的“多变量”细观力学模型进行比较。此外，研究结果还将为基于塑性的形状记忆合金本构模型中使用的相变应变假设提供依据。这项工作代表了对SMA行为尚未研究的方面的调查：虽然材料科学界已经处理了马氏体变体结构的识别，而力学学界已经处理了宏观建模，但对于在施加载荷下形成哪些变体以及在不同加载条件下准确地转化为宏观应变的确切理解还没有研究。然而，必须了解这些问题，才能在SMA研究和应用方面取得重大进展。

9908368BrinsonIn the work, shape memory alloy (SMA) response to uniaxial and multiaxial loading will be studied with Scanning Electron Microscopy and Electron BackScattered Diffraction. The experiments will provide detailed information on the evolution of variants under different loading conditions and will be compared to the PIs "multivariant" micromechanics model. In addition, results will give insight into the assumptions for transformation strains used in plasticity-based SMA constitutive models. The work represents investigation of aspects of SMA behavior that have not yet been examined: while the materials science community has dealt with identification of martensitic variant structure, and the mechanics community has dealt with macroscale modeling, a direct understanding of exactly which variants form under applied load and precisely how that translates into macroscopic strain for different loading conditions has not been studied. Yet these issues must be understood to make significant progress in SMA research and applications.