The 3D model of the structure is created in Ansys DesignModeler and meshed with solid elements. The structural bodies use SOLID185 elements. The acoustic cavities (sound port, air gap, and housing cavity) are modeled with FLUID30 elements. The air gap is meshed with a one element layer of SOLID226 electrostatic-structural elements (KEYOPT(1) = 1001) that use the elastic air option (KEYOPT(4) = 1).
The acoustic element size is chosen to ensure having at least 6 elements per wavelength for the highest frequency of interest.
All bodies are grouped in a single part to obtain node connectivity at the body's interfaces.
Fluid elements elements must be created on top of the airgap to account for vibroacoustic coupling. The following commands are used to create this
et,104,30,,,,0 keyopt,104,1,2 keyopt,104,2,0 keyopt,104,5,0 mp,sonc,104,343.24 mp,dens,104,1.2041 type,104 mat,104 real,104 cmsel,s,airgap ielem=0 *get,ecount,elem,0,count *do,ar20,1,ecount cmsel,s,airgap ielem=elnext(ielem) *get,n1,elem,ielem,node,1 *get,n2,elem,ielem,node,2 *get,n3,elem,ielem,node,3 *get,n4,elem,ielem,node,4 *get,n5,elem,ielem,node,5 *get,n6,elem,ielem,node,6 *get,n7,elem,ielem,node,7 *get,n8,elem,ielem,node,8 e,n1,n2,n3,n4,n5,n6,n7,n8 *enddo
