Research On Three-Phase Fiezocomposite And Curved Surface Transducer

The high-frequency transducer with broadband and wide-beam(large open angle)properties has widely demand in the forward sonar of unmanned underwater vehicle,detected sonar of the diver and high-resolution imaging sonar.To meet this requirement,a novel three-phase piezocomposite and the curve surface transducer(based on the composite)have been developed in the dissertation.The thesis includes two parts accordingly:research on the three-phase piezocomposite and the development of curve surface transducer.Base on the research status of 1-3 type piezocomposite,its improved structure(the three-phase piezocomposite)has been proposed in this dissertation.This piezocomposite consists of three-phase materials:piezoelectric ceramic,epoxy resin and silicon rubber.It not only can achieve a high electromechanical coupling factor,but also can prevent bending deformation.Meanwhile,this structure provides the convenience of curved surface forming.The equivalent parameters of the three-phase piezocomposite were deduced according to the series and parallel concept and equivalent parameters theory.The influences of piezoelectric ceramic and silicon rubber volume fractions on the characteristics parameters were analyzed.The optimized ranges of volume fraction are initially determined.Besides,the thickness vibration frequency equations were derived using electromechanical equivalence principle and the curves of thickness vibration frequency in different thickness or volume fraction was obtained.Then,three-phase piezocomposite were simulated by finite element software(ANSYS).The optimized ranges of volume fraction were confirmed further and the relationships between the characteristics of curved surface three-phase piezocomposite and radius were illustrated.The cutting and filling method was chosen as basic preparation approach of three-phase piezocomposite by comparing the current preparation methods of piezocomposite.The preparation processes of the plane and curved surface three-phase piezocomposite were established through improving and innovating the method.And then the plane and curved surface piezocomposite samples were fabricated and tested.The measured results show the electromechanical coupling factor can reach above 0.67,and theoretical calculations or simulations match experiment results basically.The radiated sound field model of the curved surface(circular-arc and two-dimensional curved surface)transducer was established using electromechanical equivalence principle and point sources sound field theory.Furthermore,the relationships between the transmitting properties of the transducer and structure parameters were analyzed.The technology of matching layer was applied to curved surface transducer for expanding the bandwidth of transducer.The radiated sound field model of curved surface transducer with matching layer was also established.The efforts parameters of matching layer on transmitting voltage response and bandwidth were studied,and based on the studies,the optimized matching layer parameters was obtained.Then the circular-arc surface transducer and two-dimensional curved surface transducer were respectively designed according to the theoretical analysis results.The preparation processes of curved surface transducer were established.The circular-arc surface transducer and two-dimensional curved surface transducer were fabricated according to the preparation processes.The test results show that the transmitting voltage response,the horizontal open angle of the beam and bandwidth of reach 167.9dB,152 ° and 110kHz,respectively;The two-dimensional curved surface transducer reaches 159.6dB,123°and 122kHz,respectively.Compared with similar product,their performance has been greatly improved.The developed transducers achieved the purpose of broadband and large open angle to radiate sound.