This research contributes to the topology optimization of acoustic–structure interaction problems with infinite acoustic domain by focusing on two issues, namely, the variation of the acoustic–structure interface and free-floating elements. To handle the variation of the coupling interface, we divide the analyzed domain into the bounded and unbounded domains by using a virtual surface. For the bounded domain where the coupling interface may appear, we model it with the mixed displacement–pressure (u/p) finite element method (mixed FEM). Then, the boundary element method (BEM) is utilized to model the non-reflecting boundary conditions on the truncated surface. The mixed FEM enables the explicit representation of the acoustic–solid interface in the optimized domain to be circumvented. By spatial variation of the mass density, shear and bulk moduli in the mixed FEM, the topology optimization procedure can be easily implemented similar to standard density approaches. With regard to the free–floating elements, we establish a connected component filter to delete these useless elements. This treatment avoids unreasonable but possibly optimized results. The proposed method is verified by several optimization examples.

这项研究通过关注两个问题，即声学-结构界面的变化和自由浮动的元素，为具有无限声域的声学-结构相互作用问题的拓扑优化做出了贡献。为了处理耦合接口的变化，我们通过使用虚拟表面将分析域分为有界和无界域。对于耦合界面可能出现的有界区域，我们用混合位移-压力（u / p）有限元法（混合有限元法）。然后，使用边界元方法（BEM）对截断表面上的非反射边界条件进行建模。混合FEM可以避免在优化域中明确表示声固界面。通过混合FEM中质量密度，剪切模量和体积模量的空间变化，可以类似于标准密度方法轻松实现拓扑优化过程。关于自由浮动元素，我们建立了一个连接的组件过滤器，以删除这些无用的元素。这种处理避免了不合理但可能优化的结果。通过几个优化实例验证了该方法的有效性。