### ASA 130th Meeting - St. Louis, MO - 1995 Nov 27 .. Dec 01

## 1pNS10. Finite element models for sound absorbing materials.

**J. Stuart Bolton
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Yeon June Kang
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*1077 Ray W. Herrick Labs., School of Mech. Eng., Purdue Univ., West
Lafayette, IN 47907-1077
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Many noise control treatments feature porous materials that are either
fibrous or foamlike. Analytical methods are available to model the behavior of
these materials in simple geometries: e.g., infinite planar or cylindrical
geometries. Realistic noise control treatments, however, are of finite size, are
often multilayered, and may have textured surfaces. If treatments of that type
are to be designed optimally, numerical models of the materials must be used.
Note also that when a surface is nonlocally reacting, the sound fields within
the treatment and in the adjacent space must be solved for simultaneously. For
both these reasons, a number of finite element formulations have been developed
to model sound absorbing materials. The first models treated the absorbing
medium as an effective fluid, and were used to model extended reaction fibrous
materials. More recently, finite element models for elastic porous materials,
i.e., foams, that are based on the Biot theory have been developed. The main
features and capabilities of these various finite element models will be
discussed in this presentation. In addition, a number of examples of their use
will be given: e.g., the optimal design of a foam wedge for sound absorption and
transmission control.