Sensing characteristics of contact-type transducer for flexural waves

For the purpose of understanding and improving the stress wave factor techn ique and the travelling wave control method, the sensing characteristics of contact-type transducers for flexural waves are investigated in this paper . Two kinds of frequency response functions (FRF) are presented to characte rize the transducer sensing results: one is for any harmonic plane wave, an d the other for any point source disturbance. The two FRF are both expresse d in the form of explicit physical interpretations which distinguish the in fluences from the transducer itself and from the tested structure. Based on this, three characteristic lines about the FRF are presented: one is a sca ttering line which means the FRF is dominated by the nature of wave scatter ing or wave reflection, the other two are transducer's mass and spring line s which imply the transducers properties dominate the FRF. Using these thre e lines, the difference between general ultrasonic transducers and general vibration transducers can be clearly identified. Finally using the fast Fou rier transform (FFT) technique, some typical time domain numerical results of the transducer output are also presented to show some important sensing characteristics. (C) 1999 Elsevier Science Ltd. All rights reserved.