温度影响下形状记忆合金/橡胶复合材料的界面力学特性及损伤行为研究

The combination of Shape memory alloy (SMA) and rubber materials creates a new kind of composite which exhibits impressive application potential because of its unique mechanical properties and good bio-compatibility. To this composite material, the interface adhesion between the inserted SMA and rubber matrix is an important factor for realizing its practical functionalities, and this factor is also greatly influenced by temperature effect. At current, there has been no enough understanding on above issue. So in this project, a systematical study will be carried out for characterizing the interface properties of the SMA/rubber composite. Firstly, the mechanical resistance of interface between SMA wire and rubber matrix are investigated through pull-out tests under different temperatures, so as to obtain the marked change in adhesion performance resulted from temperature variation. After that, the computational micro-mechanics which can take into account the interface decohesion process are conducted from the viewpoint of simulation. By employing these “virtual tests”, the finite deformation response of this composite under thermal-mechanical loadings are obtained and the effects of multi-factors including constitutive material, internal structure and bonding status of interface on its overall mechanical behavior are discussed, and then the corresponding heterogeneous mechanics and damage micro-mechanism can be revealed. Based on the works in this project, it is possible to find some methods to fully elaborate the physical nature of SMA reinforced elastomer, and these results can provide a theoretical foundation for further development and application of this material.

形状记忆合金增强橡胶是一种新型复合材料，它因具有独特的物理力学性能和良好的生物相容性而展现了较突出的应用前景。对这类材料而言，填入的形状记忆合金与橡胶基体之间的界面粘结性能是决定其能否发挥应有效用的关键因素，且这种性能表现还受到温度载荷的显著影响。目前在这方面尚缺乏足够的认识，因此有必要展开相关的研究。针对形状记忆合金/橡胶复合材料实际所处的热-力载荷工况，本项目首先通过系统的实验，考察其在温度影响下的界面粘结力学特性，获得与温度变化所对应的界面性能演变规律；其次从仿真角度出发，建立能合理计及这种界面脱粘效应的细观数值模型，以此模拟该材料在热-力载荷共同作用下的大变形力学响应，并考察材料的组分性能、结构形式、两相界面属性等多方面因素对此的影响。基于本项目的研究，将能较全面的揭示温度影响下形状记忆合金增强橡胶的细观变形演化特征和界面损伤失效机理，为该材料的进一步发展和应用提供有益的理论指导。

近年来，由柔性的橡胶高弹体与形状记忆合金组成的新型智能复合材料引起了人们兴趣和关注，这类材料拥有丰富的结构可设计性并展现出独特的物理力学性能，其发展和应用前景十分可观。由于橡胶基体和形状记忆合金增强相的受力性能差异较大，两者间的界面粘结状况就很大程度决定了该体系的功能和实用性。本项目主要针对温度影响下形状记忆合金增强橡胶的宏细观力学行为及界面损伤特性展开研究。考察了硫化与未硫化橡胶复合材料在不同温度和不同应变率下的大变形力学行为，并建立起描述这些影响因素的黏超弹性分子网络本构模型，为相关的宏细观力学表征奠定了理论基础；实施了不同温度下NiTi形状记忆合金丝在硅橡胶中的拔出试验，获得了变温条件下两者间界面粘结性能的演变规律，初步揭示了热载荷诱导的马氏体相变对该过程的影响；针对不同结构形式的NiTi/硅橡胶复合材料建立有限元数值模型，并根据需要编写相应的内聚力界面单元用户子程序，以此为基础考察了界面粘结强度和界面粘结能对这类材料纵向和横向拉伸变形行为的影响，从数值分析的角度探讨其内部界面损伤和结构演化规律；另外还以柱状晶组织Cu基形状记忆合金为对象，开展了阻尼力学行为实验，分析总结了载荷因素对该材料阻尼性能的影响机制。总的来说，本项目的研究结果将加深对形状记忆合金增强橡胶性能、结构及界面特征的认识，且有助于寻求充分发挥橡胶基体内形状记忆合金智能驱动、调控作用的方法，为该材料的发展和应用提供支持。