The design, fabrication, and acoustic calibration of a conical, octahedral array using 1-3 piezoelectric composite

Continuing to exploit the unique characteristics of 1-3 piezoelectric composite for wide-band acoustic array applications, a 120-element conical array was successfully fabricated and calibrated in less than 3 months. The eight-sided approximation of the conical aperture had dimensions 18.3 cm high, with a 13.3-cm base, and a 20 conical half-angle. Each of the 8 staves had 15 elements. The upper portion of the conical surface (cone tip) was not populated. The substrate thickness used in this demonstration was 1.8 cm providing a half-wave resonance frequency of approximately 86 kHz. The 1-3 piezocomposite configuration consisted of injection molded Navy type VI ceramic with a rigid epoxy back-fill that has proven to be both rugged and easily machined. The array was air backed. The array and tooling of the mechanical components were modeled using a computer-aided design package, and subsequently fashioned using stereo-lithography apparatus thus making this array a paperless design. Radiation modeling was accomplished using the Combined Helmholtz Intergral Equation Formulation (CHEIF). Measured results will include in-air laser vibrometer scans, and in-water transmit and receive beam patterns. [Work supported by Naval Sea Systems Command Div. Newport (Code 82).]