Vibration characterisation of cymbal transducers for power ultrasonic applications

Abstract

School of Engineering, University of Glasgow, Glasgow G12 8QQ, UK E-mail: f.bejarano-duran.1@research.gla.ac.uk Abstract. A Class V cymbal flextensional transducer is composed of a piezoceramic disc or ring sandwiched between two cymbal-shaped shell end-caps. These end-caps act as mechanical transformers to convert high impedance, low radial displacement of the piezoceramic into low impedance, large axial motion of the end-cap. The cymbal transducer was developed in the early 1990's at Penn State University, and is an improvement of the moonie transducer which has been in use since the 1980's. Despite the fact that cymbal transducers have been used in many fields, both as sensors and actuators, due to its physical limitations its use has been mainly at low power intensities. It is only very recently that its suitability for high amplitude and high power applications has been studied, and consequently implementation in this area of research remains undeveloped. This paper employs experimental modal analysis (EMA), vibration response measurements and electrical impedance measurements to characterise two variations of the cymbal transducer design, both aimed at incorporation in ultrasonic cutting devices. The transducers are fabricated using the commercial Eccobond 45LV epoxy adhesive as the bonding agent. The first cymbal transducer is of the classic design where the piezoceramic disc is bonded directly to the end-caps. The second cymbal transducer includes a metal ring bonded to the outer edge of the piezoceramic disc. The reason for the inclusion of this metal ring is to improve the mechanical coupling with the end-caps. This would therefore make this design particularly suitable for power ultrasonic applications, reducing the possibility of debonding at the higher ultrasonic amplitudes. The experimental results demonstrate that the second cymbal design is a significant improvement on the more classic design, allowing the transducer to operate at higher voltages and higher amplitudes, exhibiting a linear response over a practical power ultrasonic device driving voltage range. The results also show that the device can be accurately tuned using finite element modelling and that the cymbal exhibits a modal response as predicted by the finite element models.

A Comparison of Two Configurations for a Dual-Resonance Cymbal Transducer

“…Recent research has demonstrated the potential of the cymbal for power ultrasonics applications [6][7][8] and a modification of the classical cymbal design, with a single end-cap, has been developed as a prototype ultrasonic orthopaedic surgical device [9].…”

Differential scanning calorimetry of superelastic Nitinol for tunable cymbal transducers

“…Eliminating the asymmetric mode, whose frequency change is difficult to predict, from the frequency response, may be desirable in order to design and operate a reliable tunable cymbal transducer based on control of one modal response. However, eliminating asymmetries may not be realistic for the classical cymbal configuration and a modified version, similar to some that have previously been proposed (Bejarano et al, 2012(Bejarano et al, , 2014Lin, 2010), may be preferable.…”

“…The main limitation for adoption in high-power applications is that the epoxy resin used to form the mechanical coupling is insufficient for the higher stresses associated with the higher power levels (Lin, 2010). Consequently, in recent years, there have been a number of proposed modifications of the cymbal transducer (Bejarano et al, 2012(Bejarano et al, , 2014Lin, 2010), for example, for incorporation in an ultrasonic orthopedic surgical device (Bejarano et al, 2014).…”

Modal analysis and nonlinear characterization of an airborne power ultrasonic transducer with rectangular plate radiator

“…A new APU transducer has been developed in order to assist mass transfer processes intensification for the food industry, based on previous experimental studies that have demonstrated the efficiency of APU in the enhancement of low temperature dehydration processes [15,16]. The development of this technology can be divided into three stages: (1) a theoretical design applying the constitutive equations [17][18][19], (2) a numerical analysis using a finite element model [20][21][22], and (3) an experimental characterization at low and high power operation including modal analysis, stability tests and nonlinear behavior [23][24][25].…”