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基于对伪弹性形状记忆合金(SMA)典型应力-应变曲线的特征分析,在原Graesser本构模型中增加简洁多项式来描述SMA应力诱发马氏体相变完成后在变形马氏体相下继续加载阶段的变形特征;并引入应变幅值与混相下SMA弹性模量的关系来改进不同应变幅值下卸载时SMA的应力-应变关系,从而提出了一种新的SMA一维本构关系模拟其伪弹性力学行为。该模型对直径为0.5mm的NiTi合金丝的拉伸加载、卸载试验曲线的模拟结果表明:改进本构模型与原Graesser模型相比,其能够准确地模拟SMA在不同应变幅值下加载和卸载应力-应变关系。此外,通过研究SMA本构模型的物理关系,推导出了控制SMA滞回曲线特征的关键参数fT与相变临界应力、弹性常数之间的明确关系,可利用该关系直接确定参数fT,摆脱了只靠试算获取该参数的传统做法,其准确性得到了试验验证。
Based on the characterization of the typical stress-strain curve of pseudo-elastic shape memory alloy (SMA), concise polynomials are added to the original Graesser constitutive model to describe the SMA-induced martensitic transformation after the deformation phase continues to be loaded The relationship between the strain amplitude and the elastic modulus of SMA under mixed phase was introduced to improve the stress-strain relationship of SMA at unloading under different strain amplitudes. A new SMA one-dimensional constitutive relation was proposed to simulate its pseudo-pseudo- Elasticity behavior. The simulation results of tensile loading and unloading test curves of NiTi alloy wire with diameter of 0.5mm showed that the improved constitutive model can accurately simulate the loading and unloading of SMA under different strain amplitudes compared with the original Graesser model Stress-strain relationship. In addition, by studying the physical relationship of SMA constitutive model, the explicit relationship between the critical parameter fT, which controls the characteristics of SMA hysteresis curve, and the critical stress and phase transition elastic constant is deduced. The relationship can be used to directly determine the parameter fT and get rid of The accuracy of this parameter has been experimentally validated only on a trial basis.