Low-frequency and high-sensitivity laminated beam-based acceleration sensors for vector hydrophones

The piezoelectric acceleration sensor is the core part of an acoustic vector hydrophone.In order to meet the application requirement of the low-frequency and high-sensitivity vector hydrophone,an acceleration sensor with the Laminated Beam(LB) structure is proposed.The analytic expression of acceleration sensitivity of the LB-based acceleration sensor is derived according to the elastic mechanics and piezoelectric equations.The size of LB-based acceleration sensor is optimized by finite element simulations and the resulting size-range is presented.Then two LB-based acceleration sensors with different sizes are chosen for the vibration characteristic analysis,physical production with the PZT-5 piezoelectric ceramic material,and performance test.Both the simulations and the test results show that LB-based acceleration sensor effectively reduces the resonance frequency and promotes sensitivity,compared with the same-size Metal Beam(MB)-based acceleration sensor.In terms of the PZT-5 piezoelectric ceramic material with 0.5 mm thickness,there are an improvement of 3.9 dB for the acceleration sensitivity and a decrease of 23% for the resonance frequency.In sum,the actual test results are coincident with the theoretical analysis results.