夹心式径向复合压电超声换能器

对夹心式径向复合压电换能器径向振动特性进行了研究。该换能器由弹性内芯、预应力金属管及柱面压电陶瓷晶堆径向复合而成.利用机电类比法,得到了换能器的径向振动等效电路及频率方程。探讨了换能器第1、2阶径向共振频率及有效机电耦合系数与其几何尺寸的关系。研究表明,换能器第1阶径向共振频率随其内芯内径及预应力管壁厚度增大而降低;第2阶共振频率随内芯内径增大存在极小值,但随预应力管壁厚度增大单调下降。此外,采用第2阶径向共振模式能获得较高的有效机电耦合系数,并且压电陶瓷处于位移节线时,换能器有效机电耦合系数达极大值。对换能器共振频率的测试与有限元仿真表明。理论与实验及仿真结果符合较好。 

The sandwiched radial composite piezoelectric ultrasonic transducer

The radial vibration of a sandwiched radial composite piezoelectric ultrasonic transducer is studied. The transducer consists of a metal inner core, a prestress tube and a ring group of piezoelectric ceramic piles. Based on the electro-mechanical analogy, the equivalent circuit and the resonance frequency equation of the transducer in radial vibration are derived. The relationship between the first and second order resonance and anti-resonance frequency, the effective electro-mechanical coupling coefficient and the geometrical dimensions of the transducer is analyzed. It is illustrated that the first radial resonance frequency of the transducer are decreased with the inner diameter of the inner core and the wall thickness of the outer prestress tube of it are increased. The second radial resonance frequency of the transducer gets extremum value with the increase of the inner diameter of the inner core, but it decreased monotonically with the wall-thickness of the outer prestress tube increased. Besides, the effective electro-mechanical coupling coefficient of the transducer at the second order vibration mode is higher than that of the first order. Especially, it reach maximum when the piezoelectric ceramic component located in the radial displacement node line. By testing and simulating the radial resonance frequencies of some radial sandwiched transducers. It is shown that the theoretical radial resonance frequencies are in a good agreement with the measured and simulated results.