Design Of Passive Vibration Isolation Platform For Helicopter Airborne Tracking-Aiming System

The vibration isolation platform between the helicopter airframe and the photoelectric pod is an important equipment to ensure the stability of the sight and sight system,and it has an important influence on the accuracy of the helicopter.In view of the fact that the performance of the original vibration isolation platform of a certain type of surveillance and attack helicopter does not meet the requirements,this paper designs a vibration isolation platform based on passive vibration isolation technology for a certain type of attack helicopter.The main work of the thesis is as follows:(1)According to the vibration environment of the helicopter airborne tracking system and the specific requirements of the vibration isolation platform structure,a vibration isolation platform structure with an even number of vibration isolators in parallel and installed vertically was designed.The material of the vibration isolator choose 60Si2 Mn A and the metal rubber10Cr21Mn16 Ni N as the damping element.By repeatedly adjusting the geometric parameters of the vibration isolator,the stiffness of the isolator is changed and the ratio of the excitation force frequency to the natural frequency of the system is 2.5.(2)The geometric model was established by SOLIDWORKS,and ANSYS was used for finite element calculation,and the stress redundancy and stiffness parallelism of the vibration isolation platform were checked during the vertical 3G overload and the horizontal/longitudinal2.5G overload.(3)The space attitude transformation function of the platform was obtained by the Euler rotation theorem,the system dynamics equation was established by the Lagrange method,and the time domain response of the vibration isolation system was solved by the fourth-order Runge-Kutta method.Through the fast Fourier transform,the spectrogram was obtained from the time domain response curve and compared with the finite element results to verify the correctness of the dynamic model.(4)Through experiments,the stiffness and damping of the vibration isolation platform were measured,the vibration transmission rate curve was drawn,and the vibration isolation performance of the vibration isolation platform was evaluated.(5)Through flight tests,acceleration transmission rates at several excitation frequencies were obtained.A comparison with the test results of the original vibration isolation platform design scheme proves that the design scheme in this paper is superior to the existing scheme and has been adopted.