Study Of Thin-Walled Structure With Viscoelastic Damping Under Impact Loadings In Vibration And Noise Reduction

In this paper, thin-walled structures of aircraft often subjected strong impact loadings in the time domain and seriously structural vibration and noise radiation. The problem is seriously damage the assembly workers’ audition and influence of assembly quality and working efficiency. So the author proposed the use of damping technique to alleviate this problem. The paper is focuses on using numerical calculation method to simulate the impact on the characteristics of vibration response and sound radiation metal thin-walled structures of impact load, and the effect of reducing vibration and noise radiation by imposing constrained damping, as well as change the damping parameter as and laying methods, summed up the vibration and radiation characteristics of constrained damping structure and rules.Firstly, it is mainly adopts the coupled finite element and boundary element method, and the transient displacement response and structural acoustic radiation characteristics calculation model of a thin plate under impact load was established. After calculation, it is trying to obtain the vibration displacement node and natural frequency and the transient displacement power spectrum density, along with the sound power of radiation noise and sound pressure level of any point of space.Secondly, it is establish the all laying constrained damping of thin-walled metal structures model, which is in order to calculation the effect of damping on the vibration and acoustic radiation of the structure. It is focusing on the difference of vibration noise response of the structure form different impact load,size and thickness of damping layer.In the next place, it is also based on partial damping structure model, after using numerical simulation method to simulation the damping vibration displacement response of structure and the sound power calculation. As well as discussed the influence of vibration noise of the structure by different damping layer.Finally, a fixed all corners constrained damping plate has been simulated and optimized. The square of the vibration velocity is selected as objective function which is based on the relationship between acoustic radiation power and vibration velocity of the surface of structure. And the thickness of each layer and the total mass of structure are selected as design variable and state variable.In this paper, vibration and sound radiation were studied when a thin-walled structure was loaded impact loadings. Application of numerical simulation method to analyze the various parameters of the constrained damping effect on the vibration and noise reduction.and optimize the design of thickness of each layer to reduce the vibration and acoustic radiation power. The results have a certain reference and application value in equipment research and work efficiency.