驻波超声电机定动子表面微织构与摩擦化学作用协同减磨机理研究

Standing wave ultrasonic motors have grown to become a research focus in the field of microscopic linear actuator and/or motor because of their outstanding advantages. However, severe wear of the stator/slider restricts the further development and application of standing wave ultrasonic motors. The large variation of contact stresses and strongly dynamic impact is prone to generate the severe wear of stator/slider and shorten the lifespan of standing wave ultrasonic motors. A synergistic anti-wear method based on laser surface textures and tribochemical actions for standing wave ultrasonic motor is proposed: Considering factors such as the inertia force of ultrasonic vibration, the tangential contact rigidity and the surface roughness, the evolution law of microscopic friction characteristics of the stator/slider of standing wave ultrasonic motor is analyzed, and the operational performance and attenuation behavior of given ultrasonic motors is investigated experimentally. Smoothed particle hydrodynamics method is utilized to analyze the damage formation process, and the effects of surface roughness and microscopic textures on the damage characteristics of contact surfaces of the stator/slider pair are investigated. Then the relationship between the dimensions of typical debris and the surface properties of friction materials was set up based on the brittleness fracture theory, and an evaluation method of wear resistance is proposed for restricting of wear debris and controlling of wear behavior. Finally, the control theory and technical system of the friction and wear behaviors of stator/slider of the standing wave ultrasonic motors are established on the basis of synergetic effect of surface textures and tribochemistry.

驻波超声电机因诸多优势，成为微小型直线驱动器领域内的研究热点，但定动子之间剧烈的磨损限制了进一步发展和应用。针对直线驻波超声电机定动子接触应力变化大、冲击作用强、表面磨损剧烈而性能寿命短等问题，提出定动子接触表面微织构与摩擦化学作用协同减磨方法：考虑振动惯性力、切向刚度及表面粗糙度等因素，分析驻波超声电机在运行过程中定动子摩擦特性的演变规律；通过实验研究揭示驻波超声电机运行过程中输出性能衰减机理，并运用光滑离子动力学方法模拟分析定动子接触表面缺陷形成机制，研究表面粗糙度及微织构对亚表层损伤特征的影响规律；应用材料脆性断裂理论建立特征磨粒尺寸与配副表面性能特征参数之间的定量关联，提出定动子摩擦配副表面耐磨性的评价方法；基于定动子表面微织构与摩擦化学的协同作用，建立驻波超声电机定动子摩擦磨损调控理论与技术体系。

驻波超声电机因具有诸多优势而成为微小型直线驱动器领域内的研究热点，但定动子的剧烈磨损和低可靠性限制了发展和应用。该项目针对直线驻波超声电机定动子接触应力变化大、冲击作用强、表面磨损剧烈而性能寿命短等问题，开展了定动子接触界面的系统性摩擦学研究。考虑振动惯性、切向刚度及表面粗糙度等因素分析驻波超声电机在其磨损过程中定动子微观摩擦特性的演变规律；通过实验研究揭示驻波超声电机运行过程中输出性能衰减特性，接触宽度随着磨损厚度增大而减小，切向冲击作用逐渐减弱，最终导致摩擦传递性能降低，造成马达输出性能衰减。此外，运用动态有限元方法模拟定动子接触表面缺陷形成机制，。研究表面粗糙度及微织构对亚表层损伤特征的影响规律，表面粗糙度Ra在0.15~0.7μm范围内变化时，通过优化表面粗糙度可以提升最大负载能力58%，空载速度提升了26%。表面织构对驱动速度和推力的影响趋势往往相反，但实施表面织构可以提高电机的输出功率和延长服役性能寿命，尤其是表面织构面积占比为42%时，电机的空载速度和推力达到极大值，输出功率提升20%以上。应用材料脆性断裂理论建立特征磨粒尺寸与配副表面性能特征参数之间的定量关联（主要参数涉及晶粒大小、脆性指数和塑性指数），提出定动子配副摩擦表面耐磨性水平的定量评价方法；提出了驻波直线超声电机定动子摩擦表面温升计算方法，解释了某摩擦配副在滑动摩擦和超声冲击作用下的摩擦氮化及电机长寿命运行的原因。定动子间歇接触可将机械滚压、摩擦和冲击产生的热量合理分配，产生低剪切强度固溶体及氧化膜，使电机获得良好的输出性能和稳定的运行状态。实现驻波直线超声电机的往复运行寿命高达120万余次。该项目工作能够为驻波直线超声电机定动子界面系统性摩擦学设计、动力学性能优化和界面热力学分析提供重要支撑，也为定动子表面微结构设计与制造和驻波直线电机性能寿命测评提供了有益参考。