• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文学位 >Les mousses adaptatives pour l'amelioration de l'absorption acoustique: Modelisation, mise en oeuvre, mecanismes de controle.
【24h】

Les mousses adaptatives pour l'amelioration de l'absorption acoustique: Modelisation, mise en oeuvre, mecanismes de controle.

机译：用于改善吸声的自适应泡沫：建模，实施，控制机制。

获取原文
获取原文并翻译 | 示例
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

The objective of this thesis is to conduct a thorough numerical and experimental analysis of the smart foam concept, in order to highlight the physical mechanisms and the technological limitations for the control of acoustic absorption. A smart foam is made of an absorbing material with an embedded actuator able to complete the lack of effectiveness of this material in the low frequencies (500Hz). In this study, the absorbing material is a melamine foam and the actuator is a piezoelectric film of PVDF.;A 3D finite element model coupling poroelastic, acoustic, elastic and piezoelectric fields is proposed. The model uses volume and surface quadratic elements. The improved formulation (u,p) is used. An orthotropic porous element is proposed. The power balance in the porous media is established. This model is a powerful and general tool allowing the modeling of all hybrid configurations using poroelastic and piezoelectric fields.;Three smart foams prototypes have been built with the aim of validating the numerical model and setting up experimental active control. The comparison of numerical calculations and experimental measurements shows the validity of the model for passive aspects, transducer behaviors and also for control configuration.;The active control of acoustic absorption is carried out in normal incidence with the assumption of plane wave in the frequency range [0-1500Hz]. The criterion of minimization is the reflected pressure measured by an unidirectional microphone. Three control cases were tested: off line control with a sum of pure tones, adaptive control with the nFX-LMS algorithm for a pure tone and for a random broad band noise. The results reveal the possibility of absorbing a pressure of 1.Pa at 1.00Hz with 100V and a broad band noise of 94dB with a hundred Vrms starting from 250Hz. These results have been obtained with a mean foam thickness of 4cm. The control ability of the prototypes is directly connected to the acoustic flow. An important limitation for the broad band control comes from the high distortion level through the system in the low and high frequency range (500Hz, > 1500Hz).;The use of the numerical model, supplemented by an analytical study made it possible to clarify the action mode and the dissipation mechanisms in smart foams. The PVDF moves with the same phase and amplitude of the residual incidental pressure which is not dissipated in the foam. Viscous effect dissipation is then very weak in the low frequencies and becomes more important in the high frequencies. The wave which was not been dissipated in the porous material is transmitted by the PVDF in the back cavity.;The outlooks of this study are on the one hand, the improvement of the model and the prototypes and on the other hand, the widening of the field of research to the control of the acoustic transmission and the acoustic radiation of surfaces. The model could be improved by integrating viscoelastic elements able to account for the behavior of the adhesive layer between the PVDF and foam. A modelisation of electro-elastomers materials would also have to be implemented in the code. This new type of actuator could make it possible to exceed the PVDF displacement limitations. Finally it would be interesting for the industrial integration prospects to seek configurations able to maximize acoustic absorption and to limit the transmission and the radiation of surfaces at the same time.
机译：本文的目的是对智能泡沫概念进行全面的数值和实验分析，以突出控制吸声的物理机理和技术局限性。智能泡沫由具有嵌入式执行器的吸收材料制成，该执行器能够完全弥补这种材料在低频（<500Hz）时缺乏有效性的问题。在这项研究中，吸收材料是三聚氰胺泡沫，致动器是PVDF的压电膜。；提出了一个耦合多孔弹性，声学，弹性和压电场的3D有限元模型。该模型使用体积和表面二次元素。使用改进的公式（u，p）。提出了正交各向异性多孔元件。建立了多孔介质中的功率平衡。该模型是功能强大且通用的工具，可以使用多孔弹性和压电场对所有混合构型进行建模。;已经建立了三个智能泡沫原型，旨在验证数值模型并建立实验主动控制。数值计算与实验测量结果的比较表明，该模型对于无源方面，换能器性能以及控制配置均有效。 0-1500Hz]。最小化的标准是单向麦克风测得的反射压力。测试了三种控制情况：具有纯音的离线控制，具有纯音和随机宽带噪声的nFX-LMS算法的自适应控制。结果揭示了在100V的1.00Hz下吸收1.Pa压力的可能性以及从250Hz开始的100Vrms吸收94dB的宽带噪声的可能性。这些结果是在平均泡沫厚度为4厘米的情况下获得的。原型的控制能力直接与声流有关。宽带控制的一个重要限制来自于系统在低频和高频范围（<500Hz，> 1500Hz）中的高失真水平;数值模型的使用以及分析研究的补充使澄清成为可能智能泡沫的作用方式和耗散机制。 PVDF以残余偶然压力的相同相位和幅度移动，而残余偶然压力并未在泡沫中消散。粘性效应的耗散在低频时非常弱，而在高频时则变得更加重要。 PVDF在后腔中传播了未消散在多孔材料中的波。这项研究的目的一方面是模型和原型的改进，另一方面是模型的扩展。控制声传输和表面声辐射的研究领域。通过整合能够说明PVDF和泡沫之间的粘合层行为的粘弹性元件，可以改善模型。电弹性体材料的模型化也必须在代码中实现。这种新型的执行器可以超越PVDF的位移限制。最后，对于工业集成前景而言，寻找能够最大化吸声并同时限制表面的透射和辐射的配置将是有趣的。

著录项

  • 作者

    Leroy, Pierre.;

  • 作者单位

    Universite de Sherbrooke (Canada).;

  • 授予单位 Universite de Sherbrooke (Canada).;
  • 学科 Engineering General.;Physics Acoustics.;Physics General.
  • 学位 Ph.D.
  • 年度 2008
  • 页码 266 p.
  • 总页数 266
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 工程基础科学;物理学;声学;
  • 关键词

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号