Dynamic Characteristics Test And Modal Analysis For Wave Glider

Wave Glider is a new type of ocean Autonomous Observation Vehicle(AOV),which can use the rich marine energy to sustain the long-duration and further-voyage ocean observing activities.The marine environment is complex and changing.Wave Glider is prone to violent vibration,which threatens the safety of WG operation,under the condition of alternating loads.The dynamic characteristics of the key components of the wave glider,can not only guide its structural optimization,but also provide reliable data for the reliability evaluation of the WG.In this paper,the dynamic characteristics of the surface mother-boat,the underwater tractor cradle and the gliding wing have been studied by test mode analysis.The results of this research have important guiding significance to the optimization design and the reliability evaluation of the WG.Main research works are as follows:(1)The dynamic characteristic parameters of the key components of the WG are calculated by computational modal analysis using ANSYS software,and the parameters are provided for the experimental modal analysis of the WG.(2)According to the structure characteristics of the thin-walled shell of the surface mother-boat,the sine slow sweep mode test in motivating with shaker of the hull is designed.The experimental modal system with hammering method of the underwater tractor cradle is designed,considering the characteristics of frame structure.The influence of the hanging point and the test points position on the modal test results is also discussed,and the hammering mode test of the wing is designed,in view of the thin structure of the gliding wing,the hammer is selected and the trigger force is set.Then,the modal tests of the WG have been completed respectively.(3)The dynamic characteristic parameters of the key components of the WG are identified using frequency domain method.The dynamic characteristic parameters mainly include the 16 th order natural frequency of surface mother-boat,the 15 th order natural frequency of the underwater tractor cradle,the 16 th order natural frequency of the gliding wing,mode shape and damping.Furthermore,combined with the results of FEA analysis,the weak-point of the structure is found by analyzing the modal shape.(4)The modal synthesis of the underwater tractor machine was conducted by ANSYS.The first four modal frequencies and modes of the underwater tractor were obtained by using the fixed interface method.The analysis results provide data for the reliability evaluation of the whole machine.