面向欠驱动康复机器手的NiTi多重记忆材料激光焊接及其功能损伤机理研究

NiTi Multiple Memory Materials (MMMs) has showed promising application in the rehabilitation robot industry. However, two issues including welding process and functional evaluation have to be addressed for their long-term development. In this research proposal, we aim to study the NiTi MMMs functional fatigue and failure mechanism in aspects of constitutive model, multi-physical numerical simulation and serious experiments including laser welding, resistance thermal drive and multi-axial thermal-mechanical fatigue tests. In details, we will first discuss the effects of laser processing technology on weld structure, martensite phase transformation and thermal-dynamic response of the NiTi MMMs, and then investigate the influence of force and loading method on energy dissipation and plastic deformation by analyzing the phase transformation behavior under multi-axes thermal-mechanical cycling. The mechanism of micro-crack initiation, evolution and gathering in NiTi MMMs will be studied as well, and this would contribute to the development of a multi-dimensions fatigue model. We will also evaluate the MMM damage behavior at micro level by characterizing their mechanical and electrical properties, and investigate the correlation of fatigue-induced function failure at micro and macro levels. At last, we would develop a protocol on functional assessment and fatigue life prediction for 4 knuckles rehabilitation robots. We believe that this research can promote the application of NiTi MMMs in underactuation rehabilitation robot, and benefit the development of reliable welding technology for functional materials.

针对下一代医疗康复机器手对新型功能材料的重大需求以及焊接加工、功能研判等技术瓶颈，本项目以NiTi多重形状记忆材料（Multiple Memory Materials, MMMs）为对象，开展相变可控的激光焊接制造技术及功能损伤机理研究。研究工艺参数对组织成分、马氏体相变和宏观热动力学响应的影响规律，建立组织和功能梯度连续性本构模型；搭建多轴多自由度热-机械疲劳测试系统，结合电-热-力多物理场仿真分析复杂服役工况下的相变棘轮行为，揭示加载方式、水平对宏观耗散能的影响；综合原位观测和电测法研究微观损伤动态演变机制，建立NiTi MMMs的多尺度损伤模型及三接头四关节机器手康复训练功能评定的方法体系。研究成果对阐明NiTi MMMs激光焊接分区相变控制机制，揭示其疲劳损伤失效机理具有重要意义，并为小型化、个体化、智能化欠驱动康复机器手的研制应用提供技术支撑。

以外骨骼康复机器手为代表的智能服务机器人有望率先在助老助残、医疗康复等领域实现批量生产应用并发挥重大作用，多重记忆材料（Multiple Memory Materials, MMMs）巧妙的实现了整体结构上局部SME或PE特性的独立设计和控制，可以满足康复机器手不同部位的使用需求。分区相变与功能的定量化控制是实现多重记忆材料的关键和制约瓶颈。本项目基于连续介质损伤力学建立了NiTi MMMs激光焊接制造工艺、相变/形变机制与组织结构、微裂纹扩展之间的量化关系，从宏观特征和微观表征两方面解释了疲劳损伤机理，从根本上指导了材料在复杂工况下的功能性评价研究。揭示了NiTi 多重记忆材料（MMMs）组织成分的选择性生成和相变控制机制，完善了激光焊接工艺和技术；阐明了多轴多自由度热-机械循环工况下NiTi MMMs功能疲劳损伤机理，建立了宏-微观连续损伤失效评价方法和疲劳寿命预测模型。获得了稳定、可靠的长寿命NiTi MMMs材料，并在“小护士”智能机器人、可变翼面结构上实现示范应用。在NiTi MMMs功能测试、型面可变智能装备等方面申请发明专利5项；发表高水平论文13篇，撰写结题报告1份。参加国内外学术会议10人次，包括亚洲机械电子学术会议、International Conference on Advanced Materials Research等。与滑铁卢大学先进材料连接中心、葡萄牙新里斯本大学取得了进一步深入合作，实现共同发表论文8篇。研究成果为解决困扰康复机器手等临床医疗中多重记忆材料的焊接制造问题提供了技术和工艺支持，具有较大的潜在工业应用价值。