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Wave propagation analysis for a second strain gradient rod theory

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Chinese Journal of Aeronautics 2020年第10期33卷 2563-2574页

作者： Guang ZHU Christophe DROZ Abdelmalek ZINE mohamed ichchou Vibroacoustics&Complex Media Research Group LTDS–CNRS UMR 5513Centre Lyonnais d’Acoustique CeLyAEcole Centrale de LyonUniversite de LyonFrance Institute Camille Jordan–CNRS UMR 5208 Ecole Centrale de LyonFrance

In this work,an enriched model describing the longitudinal wave propagation is established based on Mindlin’s Second Strain Gradient(SSG)theory,which can describe the heterogeneity caused by the micro-structure interactions in the frame of continuum *** governing equation and associated boundary conditions are derived based on Hamilton’s principle,then the dispersion relation of non-classical longitudinal wave together with the extra-waves appearing exclusively in SSG theory model are *** investigations are based on the modal density,energy flow,and forced response of the *** transmission and reflection through planar interfaces based on the proposed model have been ***,the results of the enriched model are well interpreted by comparing with the classical theory results,and some useful conclusions are derived on the SSG theory based model in the wave propagation characterization.

关键词： Dynamic behavior Energy flow Enriched rod model Reflection and transmission Second strain gradient theory Wave propagation features

An inverse method for characterization of dynamic response of 2D structures under stochastic conditions

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Chinese Journal of Aeronautics 2024年第3期37卷 440-455页

作者： Xuefeng LI Abdelmalek ZINE mohamed ichchou Noureddine BOUHADDI Pascal FOSSAT Laboratory of Tribology and Systems Dynamic Central School of LyonEcully 69134France Institut Camille Jordan Central School of LyonEcully 69134France Department of Applied Mechanics University of Burgundy Franche-ComtéBesancon 25000France

The reliable estimation of the wavenumber space(k-space)of the plates remains a longterm concern for acoustic modeling and structural dynamic behavior *** current analyses of wavenumber identification methods are based on the deterministic *** this end,an inverse method is proposed for identifying wave propagation characteristics of twodimensional structures under stochastic conditions,such as wavenumber space,dispersion curves,and band *** proposed method is developed based on an algebraic identification scheme in the polar coordinate system framework,thus named Algebraic K-Space Identification(AKSI)***,a model order estimation strategy and a wavenumber filter are proposed to ensure that AKSI is successfully *** main benefit of AKSI is that it is a reliable and fast method under four stochastic conditions:(A)High level of signal noise;(B)Small perturbation caused by uncertainties in measurement points’coordinates;(C)Non-periodic sampling;(D)Unknown structural *** validate the proposed method,we numerically benchmark AKSI and three other inverse methods to extract dispersion curves on three plates under stochastic *** experiment is then performed on an isotropic steel *** investigations demonstrate that AKSI is a good in-situ k-space estimator under stochastic conditions.

关键词： Inverse method Dispersion relation Wavenumber space Periodic plates Stochastic conditions Wave propagation characterization

Enhanced wave and finite element method for wave propagation and forced response prediction in periodic piezoelectric structures

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Chinese Journal of Aeronautics 2017年第1期30卷 75-87页

作者： Fan Yu Manuel Collet mohamed ichchou Li Lin Olivier Bareille Zoran Dimitrijevic Laboratory of Tribology and Systems Dynamic Ecole Centrale de Lyon Ecully 691304 France School of Energy and Power Engineering Beihang University Beijing 100083 China PSA Peugeot Citroen Paris F-78943 France

As a promising numerical tool of structural dynamics in mid- and high frequencies, the wave and finite element method（WFEM） is receiving increasingly attention and applications. In this paper, an enhanced WFEM has been developed with a reduced model and a new eigenvalue scheme. The reduced model is applicable for structures with piezoelectric shunts or local dampers;the new eigenvalue scheme can mitigate the ill-conditioning when the wave basis is calculated. The enhanced WFEM is applied to a thin-wall structure with periodically distributed piezoelectric materials（PZT）. Both free wave characteristics and forced response are analyzed and the influences of the suggested enhancements are presented. It is shown that if the control factors are properly chosen, these enhancements can improve the accuracy while accelerating the calculation. Resulting from the complexity of the application, these enhancements are not optional but imperative.

关键词： Eigenvalue scheme Periodic structure Piezoelectric shunt Reduced model Thin-wall structure Wave and finite element method

Investigation of dynamics of discrete framed structures by a numerical wave-based method and an analytical homogenization approach

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Chinese Journal of Aeronautics 2017年第1期30卷 66-74页

作者： Zhou Changwei Sun Xiangkun mohamed ichchou Abdel-Malek Zine Jean-Pierre Lainé Stephane Hans Claude Boutin Laboratory of Tribology and Systems Dynamics Ecole Centrale de Lyon Ecully 69134 France Institut Camille Jordan Ecole Centrale de Lyon Ecully 69134 France Laboratory of Tribology and Systems Dynamics Ecole Nationale des Travaux Publics de l'Etat Vaulx-en-Velinx 69518 France

In this article, the analytical homogenization method of periodic discrete media（HPDM）and the numerical condensed wave finite element method（CWFEM） are employed to study the longitudinal and transverse vibrations of framed structures. The valid frequency range of the HPDM is re-evaluated using the wave propagation feature identified by the CWFEM. The relative error of the wavenumber by the HPDM compared to that by the CWFEM is illustrated in functions of frequency and scale ratio. A parametric study on the thickness of the structure is carried out where the dispersion relation and the relative error are given for three different thicknesses. The dynamics of a finite structure such as natural frequency and forced response are also investigated using the HPDM and the CWFEM.

关键词： Framed structures Homogenization method Periodic structures Wave finite element method Wave propagation

聚氨酯制备总质量对其声学特征参数的影响分析

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长春理工大学学报（自然科学版） 2018年第5期41卷 56-59,69页

作者：王永华刘哲明许金凯于化东张成春穆罕默德.艾冲长春理工大学吉林省精密微制造技术及装备工程实验室长春130022 吉林大学工程仿生教育部重点实验室长春130025 里昂中央理工大学流体力学和声学实验室法国埃居利69134

研究了聚氨酯(PU)的制备质量(密度)对其声学特征参数的影响,为建立制备条件与其声学特征参数之间的关系奠定基础。首先制备了相同温度,相同配比,不同制备原料质量的PU泡沫,然后利用搭建的一个能够快速测试多孔材料特征参数的试验台测试... 详细信息

研究了聚氨酯(PU)的制备质量(密度)对其声学特征参数的影响,为建立制备条件与其声学特征参数之间的关系奠定基础。首先制备了相同温度,相同配比,不同制备原料质量的PU泡沫,然后利用搭建的一个能够快速测试多孔材料特征参数的试验台测试不同泡沫的吸声性能及声学特征参数,如孔隙率、流阻、曲率和特征常数等,分析了原料质量对PU声学特征参数的影响。结果表明,制备质量对PU的吸声性能具有重要影响,质量太大或者太小都会降低PU的吸声性能,原料质量为42g的PU泡沫表现出最好的吸声性能,流阻先降低后增加,孔隙率在48g时最大。

关键词：聚氨酯,声学特征参数,吸声系数