On improving the method for designing acoustic radiation mode sensor using PVDF films

Polyvinylidene fluoride (PVDF) sensors can be used to obtain the approximated radiated sound power of the vibrating structure. In designing this kind of sensors, it is difficult but important to choose the maximum order of shape coefficients and the order of the structural modes, and to determine the location of the center line for placing the PVDF pairs. In this paper, we present an improved method for solving these key issues in designing such sensors. The formulas for the shape coefficient of the PVDF pairs are derived based on the acoustic radiation modes and a PVDF sensing model. By combining structural modes and acoustic radiation modes, the rule to choose the maximum order of shape coefficients is given according to the chosen order of the structural modes, and a new approach of designing PVDF pairs in partitioned frequency band is presented to resolve the conflict in the choosing process. Finally, the optimized design approach and the criterion for determining the location of the center line for placing the PVDF pairs is given. According to the nest property of radiation modes, the amplificatory multiple of total charge response of the PVDF pair becomes linear to the exciting frequency. A number of computer simulations have been performed to demonstrate the above-mentioned conclusions.