空间多自由度柔顺并联机构疲劳损伤与疲劳可靠性分析及设计研究

Spatial multi-Degree-of-Freedom (multi-DOF) compliant parallel mechanisms have the advantages of high precision, high stiffness and high bandwidth, which are widely used in the field of micro-nano manipulation and micro-nano fabrication. The compliant mechanisms achieve movement through material deformation, which will cause serious stress. During the process of motion, the mechanisms are prone to fatigue damage and failure due to the alternating stress. Therefore, it is necessary to study the fatigue damage and fatigue reliability of spatial multi-degree-of-freedom compliant parallel mechanisms. This project aims to study the fatigue damage and fatigue reliability of spatial multi-DOF compliant parallel mechanisms. The detailed research contents include: building fatigue damage model and probabilistic fatigue life model of a typical multi-axis flexure hinge through theoretical analysis and experimental research. The spatial six DOF compliant parallel mechanism is taken as an example to study the kinematics, dynamics, static and fatigue damage modeling. The stress and strain of the hinge and its statistical characteristics are analyzed based on the stochastic finite element method. Fatigue reliability of the mechanism is then analyzed. On this basis, fatigue reliability based optimal design method is proposed. The aim of this project is to establish the fatigue damage model and probabilistic fatigue life model for flexure hinges. And then, fatigue damage prediction method for spatial multi-DOF compliant parallel mechanisms are proposed. Probability fatigue life analysis of the mechanism is conducted as well. This research will provide the theoretical basis for the fatigue reliability design and on-line performance monitoring of the spatial multi-DOF compliant parallel mechanisms.

空间多自由度柔顺并联机构能在多个方向实现纳米级运动，广泛应用于微纳操作和微纳制造等前沿领域。然而该机构依赖材料变形实现运动，在实现高精度的同时容易发生疲劳失效。为了保证机构的安全可靠运行，研究其疲劳损伤与疲劳可靠性至关重要。本项目以空间多自由度柔顺并联机构为研究对象，探讨机构疲劳损伤和疲劳可靠性建模分析与设计方法。主要研究内容包括：结合理论分析和实验研究，建立多轴柔性铰链疲劳损伤及概率疲劳模型。采用有限元法对机构运动学、静力学和动力学进行建模分析，对机构中铰链的应力应变场及其分布特性进行分析，进而基于应力强度干涉理论评估机构的疲劳可靠性。综合考虑机构运动学和动力学等各项性能，提出基于疲劳可靠性的优化设计方法。结合铰链疲劳损伤模型，探讨机构疲劳损伤性能退化规律和预测方法。本项目旨在研究空间多自由度柔顺并联机构的疲劳可靠性和疲劳损伤规律，进而为机构的抗疲劳设计和在线性能监测提供理论依据。

空间多自由度柔顺并联机构广泛应用于微纳操作和微纳制造等领域，然而其依赖材料变形实现运动，在实现高精度的同时容易发生疲劳失效。因此研究其静力学、动力学、疲劳可靠性与损伤性能至关重要。项目主要研究内容如下：设计二阶贝塞尔、正弦和辛格函数柔性铰链，给出了通用的缺口柔性铰链刚度和精度建模方法。搭建基于音圈电机驱动的柔顺机构疲劳实验台，实现柔顺机构疲劳实验及数据采集。结合理论分析和实验结果，建立铰链概率疲劳寿命模型和疲劳损伤刚度退化模型。.为实现柔顺并联机构大行程，设计了平面和空间柔顺微位移放大机构，分别基于有限元法、传递矩阵法和动力刚度矩阵法建立机构静力学和动力学模型，对比分析各方法的建模精度。优化设计了综合考虑输入刚度、应力和固有频率性能约束的高放大比柔顺机构。考虑寄生位移和旋转，提出了低寄生位移高放大比柔顺微位移放大机构拓扑优化设计方法。.设计了基于Scott-Russell机构的空间柔顺并联机构，基于动力刚度矩阵法建立静动力学模型，求解得到机构的工作空间、输入刚度和固有频率等性能参数。综合考虑尺寸参数、应力集中和平均应力影响建立铰链等效疲劳应力模型，提出机构疲劳寿命预测方法。分析机构疲劳应力和强度的分散性，基于应力-强度干涉理论建立机构疲劳可靠性模型。综合考虑工作空间、固有频率和疲劳可靠性，提出了空间柔顺并联机构疲劳可靠性优化设计方法。结合柔性铰链疲劳损伤模型，提出了机构疲劳损伤性能退化规律预测方法。预测平面柔顺并联机构疲劳损伤刚度退化性能并进行实验研究，验证了方法的有效性。本项目的研究成果将为空间柔顺机构的疲劳可靠性设计提供指导，为机构服役状态下的性能监测和损伤识别提供理论依据。