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Variability analysis of frequency dependent visco-elastic three-layered beams

机译:频率相关的粘弹性三层梁的变异性分析

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The modal stability procedure is combined with Monte-Carlo simulations to estimate the variability of natural frequencies and damping ratios of frequency dependent visco-elastic sandwich structures. In the pre-processing phase, the Diamant approach is used, at nominal, to compute complex eigenvalues and eigenmodes. Then, in the on-line phase i.e within the Monte-Carlo simulation loop, a non-linear equation is solved with Newton-Raphson algorithm to obtain perturbed complex eigenvalues. The low computational times of the method enable the use of large scale Monte-Carlo simulations yielding accurate estimates of means and coefficients of variation of frequencies and damping ratios. The method is illustrated on a three-layered sandwich rectangular beam with visco-elastic core. A frequency dependent visco-elastic material 3M ISD112 is used and two different set of boundary conditions are considered. The stochastic variables are the Young modulus of the elastic faces and the delayed elasticity shear modulus. In particular, it is shown that the mechanism of uncertainty propagation affects mostly damping ratios that experience higher coefficients of variation than natural frequencies. (C) 2015 Elsevier Ltd. All rights reserved.
机译:模态稳定性程序与蒙特卡洛模拟相结合,以估计固有频率的变化性以及与频率相关的粘弹性夹层结构的阻尼比。在预处理阶段,通常使用Diamant方法来计算复杂的特征值和特征模式。然后,在在线阶段,即在蒙特卡洛模拟回路内,使用牛顿-拉夫森算法求解非线性方程,以获得扰动的复杂特征值。该方法的计算时间短,可以使用大规模的蒙特卡洛模拟,从而得出均值以及频率和阻尼比的变化系数的准确估计。该方法在具有粘弹性芯的三层夹心矩形梁上进行了说明。使用了频率相关的粘弹性材料3M ISD112,并考虑了两组不同的边界条件。随机变量是弹性面的杨氏模量和延迟弹性剪切模量。尤其是,它表明不确定性传播的机制主要影响阻尼比,而阻尼比的变化系数要大于自然频率。 (C)2015 Elsevier Ltd.保留所有权利。

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