The 1/4 3D model of the structure is created in Ansys DesignModeler and meshed with SOLID186 elements. Flexible components such as the surround, cone, and spider are meshed with finer elements because they are of high importance. Stiffer components such as the frame, magnet, pole piece, and enclosure are meshed with coarser elements.

The acoustic elements used are FLUID220 and FLUID221. Both unsymmetric and symmetric formulations are available for fluid-structure interaction (controlled via KEYOPT(1)). The symmetric algorithm (KEYOPT(1) = 2) is used because it requires less memory and computational time. (If using the symmetric formulation, all acoustic fluid elements must have this setting, regardless of whether the elements are adjacent to structural elements.)

The PML region is specified using acoustic elements with KEYOPT(4) = 1. Approximately six elements are included in the PML region. The region between the PML region and the structure, or the “buffer” region, also includes approximately six elements. A minimum of four elements should exist in both the buffer region and the PML region. Using more elements improves accuracy (at an increase in computational cost).

Vibroacoustic problems should use shared nodes between the structural and acoustic domains. Avoid using dissimilar meshes at the interface and contact elements.

The force applied on the voice coil is modeled using SURF154 surface effect elements. A tangential load per unit area in the element’s coordinate system is applied (KEYOPT(2) = 1).