【摘要】 为了避免模态复合型超声驱动器中普遍存在的频率简并问题,提出了一种新型的弯振复合型超声驱动器。该驱动器采用压电金属复合梁两个正交弯振模态的复合在两个驱动足处激励出椭圆轨迹振动。对该驱动器的振动特性进行深入研究,旨在获得驱动区域质点的真实运动轨迹。首先,建立了矩形截面梁在弯振复合模态下末端区域质点振动轨迹的数学模型;然后,借助有限元瞬态分析,对驱动足振动轨迹进行仿真,实现对所建立振动轨迹数学模型的验证。振动轨迹方程和仿真结果均表明:两个驱动足表面质点振动轨迹均为三维的椭圆,垂直于驱动器轴线的平面内的椭圆振动更适合用于致动输出。最后,分析了该驱动器存在的不足之处,提出了一种改进方案,采用对称设置压电陶瓷片实现两个驱动足振动特性的一致;通过瞬态分析在两个驱动足处得到了一致的振动轨迹,改进的样机实现了输出特性的显著提高。更多还原

【Abstract】 In order to avoid modal frequency degeneration problems commonly existing in an ultrasonic actuator with composite vibration modes,an ultrasonic actuator with composite bending vibration modes was presented and developed.In this new design,two orthogonal bending modes of a piezoelectric-metal composite beam were superimposed to produce elliptical vibrations on its two driving feet.The real motion trajectories of particles in the driving region were obtained through studying the actuator’s vibration characteristics.Firstly,the vibration trajectory equation of a particle on the tip end of a rectangular beam under the composition of bending vibration modes was established.Then,the FE transient analysis was developed to gain the vibration trajectories of nodes on the driving feet,they verified the correctness of the built vibration trajectory equation.Both the theory and simulation results indicated that the motion trajectories of particles on the driving feet are three-dimensional ellipses;the elliptical vibration in the plane that is orthogonal to the axis of the actuator is more suitable for actuating.Finally,the disadvantage of the actuator was analyzed,an improved scheme to realize the consistent vibration on the two feet with a symmetric setting of PZT ceramics was presented.Transient analysis revealed that the same ellipses are produced on the two feet,the modified prototype has larger speed and thrust force.更多还原