Development of a vector sensor using piezoelectric support beams

Abstract

Underwater listening has attracted great interest since the twentieth century. Formerly, scalar hydrophones were used to detect sounds underwater by measuring only the pressure changes. These sensors needed to form an array to detect the direction of an incoming wave. They were positioned with intervals and the time delays of the sound among hydrophones gave the information of direction. However, vector hydrophones have become an attractive alternative since they can provide both scalar and vector information on their own. An Acoustic Vector Sensor (AVS) is a device used to detect acoustic signals by converting mechanical energy of an incident wave to a detectable electrical energy. Its design is based on two parallel piezoelectric beams attached to a mechanical sensing tip using a rotary joint component. The sensor uses piezoelectric elements to convert mechanical strain into sensible electrical signal. Design of the sensor is modular since each individual sensing element could be easily changed, tested and calibrated. All parts of sensor has been fabricated by mechanical micromachining and precisely assembled, which increases design and manufacturing exibility. In this thesis, the mechanical design of the sensor that uses the piezoelectric e ect for detection of sound is presented. First, a computational analysis method which predicts the dynamic response of the designed sensor is developed. Then, a tigthly controlled vibration experiment platform is set up to emulate the e ect of the motion of the acoustic particle. The computational simulations are then validated with initial experiments and the design of the sensor is nalized.