J. Stuart Bolton
Yeon June Kang
1077 Ray W. Herrick Labs., School of Mech. Eng., Purdue Univ., West Lafayette, IN 47907-1077
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.