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[Ph.D.] Caractérisation mécanique de matériaux fibreux en vibro-acoustique
  • Olivier Doutres, Ph.D.
This work deals with modelization and characterization of the mechanical properties of soft fibrous materials used in aeronautic industries. First, the Biot-Allard model and a simplified model dedicated to soft materials are presented. The simplified model, called limp model, assumes that the frame has no bulk stiffness. Being an equivalent fluid model accounting for the the motion of the frame, it has fewer limitations than the usual equivalent fluid model assuming a rigid frame. A criterion is proposed to identify the porous materials for which the limp model can be used : the use of the Biot model is generally recommended in the vicinity of the frame resonances. Next, three experimental methods of the characterization of elastic and damping properties of acoustic fibrous materials are presented. The main objective is to take into account the presence of the air inside and outside the porous material to insure a good evaluation of the viscoelastic properties. The first two methods are based on measurements representative of industrial use : transmission loss of large size coated panel and acoustic radiation of finite dimension vibrating multilayer plate. The use of an inverse method based on analytical models to determined the viscoelatic properties insure a good simulation of the porous material behaviour in the required context. The third method is based on a mechanical impedance measurement of a porous sample. The sample is placed in a closed cavity to take into account the effect of the air and it is loaded using an electrodynamic transducer. This method has been patented. First results validate the method.
Publication Date
September, 2007
Citation Information
Olivier Doutres. [Ph.D.] Caractérisation mécanique de matériaux fibreux en vibro-acoustique. (2007)
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