Prediction and measurements of the influence of boundary conditions in a standing wave tube

The paper concerns a comparison between measurement results of the acoustic absorption coefficient and impedance using two different methods, the standing wave tube (Kundt's tube) and a free field method. The mounting of the sample in the Kundt's tube is known to be very important. In this paper, the effect of the constraints at the tube wall on the absorption coefficient of an elastic porous material is analysed. It will be shown that the effect of the friction offered by the tube wall is to stiffen the material, compared to its behaviour in the free field. Measurement results together with model calculations are presented. The material parameters used in the models have been determined by separate measurements.

[1]  Pascal Rebillard,et al.  Modelization at oblique incidence of layered porous materials with impervious screens , 1990 .

[2]  A. Cummings,et al.  Impedance tube measurements on porous media: The effects of air-gaps around the sample , 1991 .

[3]  Manuel Melon,et al.  Experimental study of the dispersion of ultrasonic waves in porous materials , 1994 .

[4]  Ulf R. Kristiansen,et al.  On the design of resonant absorbers using a slotted plate , 1994 .

[5]  Yvan Champoux,et al.  Dynamic tortuosity and bulk modulus in air‐saturated porous media , 1991 .

[6]  Gilles A. Daigle,et al.  Electronic system for the measurement of flow resistance , 1988 .

[7]  A Cunningham,et al.  Low density cellular plastics : physical basis of behaviour , 1994 .

[8]  M. Biot.  MECHANICS OF DEFORMATION AND ACOUSTIC PROPAGATION IN POROUS MEDIA , 1962 .

[9]  P ? ? ? ? ? ? ? % ? ? ? ? , 1991 .

[10]  Bruno Brouard,et al.  FRAME DECOUPLING AT LOW FREQUENCY IN THIN POROUS LAYERS SATURATED BY AIR , 1996 .

[11]  Yvan Champoux,et al.  Air‐based system for the measurement of porosity , 1991 .

[12]  A. Craggs,et al.  A finite element method for damped acoustic systems: An application to evaluate the performance of reactive mufflers , 1976 .

[13]  J. F. Allard,et al.  Propagation of sound in porous media , 1993 .

[14]  T. Pritz,et al.  Transfer function method for investigating the complex modulus of acoustic materials: Spring-like specimen , 1980 .

[15]  Manuel Melon,et al.  Evaluation of the viscous characteristic length of air-saturated porous materials from the ultrasonic dispersion curve , 1996 .

[16]  Yeon June Kang,et al.  Finite element modeling of isotropic elastic porous materials coupled with acoustical finite elements , 1995 .

[17]  B. Brouard,et al.  A general method of modelling sound propagation in layered media , 1995 .

[18]  W. Lauriks,et al.  Displacement-based finite element method for guided wave propagation problems: Application to poroelastic media , 1996 .

[19]  G. G. Stokes.  "J." , 1890, The New Yale Book of Quotations.