形状记忆合金橡胶层状力学模型研究

Study on constitutive model of shape memory alloy pseudo-rubber based on layer decomposition

形状记忆合金橡胶是一种具有复杂多孔结构的隔振和减振阻尼材料,根据其微观结构进行层状分解,结合试块压缩刚度非线性特征得到其力学本构模型。通过引入微曲梁接触对单元,建立模型物理量与材料细观及工艺参数之间的关系,得到形状记忆合金橡胶基本单元的接触刚度;由试件非线性刚度分析得到加载、卸载过程中材料内部微曲梁接触点数量的变化,进而建立形状记忆合金橡胶层状压缩本构模型。结果表明:该模型可以考虑形状记忆合金橡胶的材料参数、加工工艺参数以及加、卸载过程中静摩擦力和滑动摩擦力的影响,更接近形状记忆合金橡胶内部微弹簧线匝的受力状态;参数分析结果表明,形状记忆合金橡胶的弹性模量随着名义密度、形状记忆合金丝直径和摩擦系数的增大而提高。

Shape memory alloy pseudo-rubber （SMAPR） is a new kind of porous damping material for isolation and vibration mitigation, with complicated internal structures. In this study, a theoretical model of SMAPR was proposed through layer decomposition according to its micro-structure and fabrication process, as well as the nonlinear stiffness characteristics. First, a contacted micro-curved-beam （CMCB） was built and the relationship between the model parameters and physical quantities of SMAPR was obtained. Then the stiffness equation was derived. Based on the analysis of the non-linear stiffness of SMAPR, the relationship between the quantity of contact points and the compression strain increment was obtained for both of loading and unloading process. Subsequently, the layer constitutive model of SMAPR was proposed and verified. A parametric analysis was conducted to investigate the effects of nominal densities, diameters of SMA wires and coefficient of friction on the behavior of SMAPR. Results show that the proposed model is closer to the real state of SMAPR, and could reflect both of the influence of micro-parameters of SMAPR and fabrication process on the macro-properties. Parametric analysis shows that the elastic modulus of SMAPR increases with the increment of nominal density, diameter of SMA wires and coefficient of friction.