Efficient Finite-Element Modeling With Equivalent-Fluid Porous Materials

The ubiquity of porous materials in engineering applications has driven a large body of work in the development of predictive and analytical models for their behavior, as well as the numerical implementation of these models. Here, the implementation of a specific class of models is described: materials for which an equivalent-fluid adequately captures the dynamic behavior. These materials include limiting cases where the solid matrix is either so stiff that it is relatively immobile, or so compliant that its motion has only a damping effect on the fluid motion. A wide class of automotive trim materials, acoustic insulation, fabrics, and aerospace materials fit this description. Several material models have been implemented recently in the commercial finite element code, Abaqus. These include the models of Craggs, Delany-Bazley, Miki, and the generalized model of Kang & Bolton. All of the models share an implementation using frequency-dependent material properties. In Abaqus, these properties are assigned to standard acoustic finite elements. Frequency-domain solution is significantly more efficient through the use of a distributed-memory parallel sparse solver, and through projection onto the space of real-valued modes. Results from the new implementation are compared to established benchmarks, and performance is discussed.