Research On Suspended Co-vibration Vector Hydrophone Based On Piezoelectric Strip

With the implementation of the national marine power strategy,higher requirements have been put forward for marine science and technology innovation.As an important sensor for underwater acoustic reception,vector hydrophone plays an important role in low-frequency long-distance detection and positioning and low-frequency noise measurement.At present,the most commonly used vector hydrophone is the co-vibration type.In practical engineering applications,it must be suspended by elastic elements and rigid suspension frames to work normally.The elastic elements and rigid suspension frames form a new suspension system with the vector hydrophone.The suspension system has natural frequencies,and improper selection of elastic elements will affect the acoustic performance of the vector hydrophone.At present,the method of analyzing the vector hydrophone suspension system is mostly based on the motion analysis of the dynamic equation.The analytical solution is obtained under the condition of the ideal lumped parameter vibration system,which can only characterize the characteristic frequency value and frequency response curve of the suspension system under the known spring elastic coefficient K.On this basis,the finite element software COMSOL is used to carry out more intuitive and concrete simulation analysis and sample test on the independent suspension system of the traditional co-vibration vector hydrophone and the suspended co-vibration vector hydrophone considering suspension and built-in accelerometer.Firstly,a vibration system model composed of solid spring and solid ball(column)is established in Solidworks software,and it is imported into COMSOL software to analyze the working frequency of the traditional independent suspension co-vibrating vector hydrophone with spring as the suspension device.The variation law of the parameters such as the diameter,diameter,original length and tensile length of the spring element is obtained.At the same time,the characteristic frequency and frequency response curve of the suspension system are obtained,especially the vibration mode(vibration mode)cloud map of the whole suspension system obtained by simulation.It can not only clearly observe the vibration state of the spring in the suspension system and the motion law of the solid ball,but also provide a basis for correctly judging the change of the attitude and acoustic performance parameters of the vector hydrophone after suspension.Secondly,based on the analysis of the vibration mode,admittance and sensitivity of two types of piezoelectric accelerometers(planar shear accelerometer and cantilever beam accelerometer)based on piezoelectric strip,the idea of embedding two types of accelerometers into the above-mentioned simulation solid sphere(column)and integrating them with the suspension spring and shell to form a new structure(with suspension and shell)vector hydrophone is proposed,and its working frequency and sensitivity are simulated.The results show that : considering the suspension problem and the structure of vector hydrophone,the elastic element and its rigid frame and accelerometer are integrated into the structural design of vector hydrophone.Not only can the vibration state of the spring system be obtained by analyzing the modal(vibration mode)cloud diagram of the overall structure of the vector hydrophone,but also the vibration influence law of the spring on the internal accelerometer can be obtained,especially the influence of the spring suspension shell.Therefore,the new structure(with suspension and shell)vector hydrophone provides a new idea for solving the engineering suspension problem of co-vibration vector hydrophone.Finally,the correctness of the above simulation results is verified by the sensitivity test of the new structure(with suspension and shell)vector hydrophone sample in the low frequency standing wave tube.At the same time,the acceleration response of the spherical vector hydrophone is tested on the vibrating table with different specifications of springs.The test results are consistent with the simulation results of the solid ball independent suspension,which provides a reference for the design of the suspension system of the traditional co-vibration vector hydrophone.