Efficient and modular acoustic substructuring using component mode synthesis

Numerical analysis of large acoustic problems, involving millions of degrees of freedom, leads to costly system analysis and design iterations. This paper presents a framework for reducing the complexity of acoustic models while preserving modularity by using component mode synthesis (CMS). The starting point is the mass, damping, and stiffness matrices obtained from a finite element discretization of the Helmholtz equation. Subsequently, we use component mode synthesis, partitioning, modal transformation, and assembly. The Hurty/Craig-Bampton and Hintz-Herting methods, traditionally used in structural component mode synthesis, are shown to be also applicable to acoustics. Additionally, we introduce a more efficient set of orthogonal interface modes, called modal constraint modes, that replace the standard constraint modes, effectively reducing the number of required interface modes for large interfaces. These methodologies are validated using a three-dimensional damped acoustic cavity model that represents a simplified lithography enclosure.