The vibration and damping analysis of an unconstrained damped plate based on randomness of viscoelastic damping layer is studied using the Monte Carlo method in this paper.The random variables follow normal distribution in this analysis.The influences of real modulus,imaginary modulus and loss factor of vis-coelastic material on the resonant frequency and the modal loss factor of the structure with different thicknesses of damping layer are analyzed.The influences of thickness of damping layer as a random variable over the whole structure and within each element are analyzed.Numerical examples show that the influence of complex modulus on resonant frequency is not significant but is considerable on modal loss factor and the influence of damping layer on modal loss factor is very notable.Therefore,the randomness of viscoelastic damping layer obviously influences the resonant response and sound radiation of structure.The influence of damping layer as random variable within each element shows that the random analysis for viscoelastic damped structure is necessary.%本文基于粘弹性阻尼层的随机性用Monte Carlo直接抽样法对自由阻尼层板的振动和阻尼进行了分析研究。分析中随机变量取正态分布。针对不同的阻尼层厚度分别考察了复弹性模量的实部、虚部、材料的损耗因子的影响。考察了整体性和局部单元性阻尼层厚度的影响。结果表明,粘弹性材料弹性模量的随机性对结构固有频率的影响不大,对模态损耗因子影响较大;不论是整体的还是局部单元的,阻尼层厚度的随机性对模态损耗因子的影响很显著。因此粘弹性阻尼层的随机性对抑制结构共振响应和声辐射的影响是较大的。阻尼层厚度局部单元随机性的影响表明了对阻尼结构采用随机分析的必要性。
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