1.10.4 Acoustic-structural interaction in an infinite acoustic medium

Products: ABAQUS/Standard  ABAQUS/Explicit  

This example is intended to illustrate and verify the use of simple absorbing boundaries and acoustic infinite elements in a coupled exterior acoustic-structural system. Problems involving infinite regions of acoustic media, solved using absorbing boundary conditions and infinite elements, are compared to converged solutions.

Problem description

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The structure is excited in all cases with a concentrated load applied to degree of freedom 2 on the node at the free (innermost) end of the shell stiffener.

The absorbing boundary tests use the *IMPEDANCE PROPERTY option to generate the necessary data automatically at the absorbing boundary. The two-dimensional circular case and reference solutions use the TYPE=CIRCULAR parameter on the *IMPEDANCE PROPERTY option. The spherical (axisymmetric) case and reference solutions use the *IMPEDANCE PROPERTY, TYPE=SPHERE option. In each of these cases only the radius of the terminating circle or sphere need be specified. In the two-dimensional elliptic case (*IMPEDANCE PROPERTY, TYPE=ELLIPTICAL) and the three-dimensional prolate spheroidal case (*IMPEDANCE PROPERTY, TYPE=PROLATE SPHEROID), additional data need to be included to specify the size and orientation of the ellipse or spheroid.

For the ABAQUS/Standard steady-state analyses using infinite elements, the infinite elements model radiation damping as well as the added mass effect, when coupled to the structural elements.

Results and discussion

Input files

Figures

Figure 1.10.4–1 Mesh configuration.

Figure 1.10.4–2 Pressure amplitude comparisons at 1, two dimensions.

Figure 1.10.4–3 Pressure amplitude comparisons at 7, two dimensions.

Figure 1.10.4–4 Pressure amplitude comparisons at 1, three dimensions.

Figure 1.10.4–5 Pressure amplitude comparisons at 40, three dimensions.

Figure 1.10.4–6 Pressure amplitude comparisons at 0.003, two dimensions, circular boundary compared to reference.

Figure 1.10.4–7 Pressure amplitude comparisons at 0.003, two dimensions, elliptical boundary compared to reference.

Figure 1.10.4–8 Pressure amplitude comparisons at 0.003, three dimensions, spherical boundary compared to reference.

Figure 1.10.4–9 Pressure amplitude comparisons at 0.003, three dimensions, prolate spheroidal boundary compared to reference.

Figure 1.10.4–10 Pressure amplitude comparisons for the transient analysis, two dimensions.