A novel application of Lagrange multipliers to couple domains modeled independently with linear elastodynamic and reduced-order theories is presented herein. This method is developed from a variational formulation of the continuous problem and is easily implemented within a finite element code. Applications include, but are not limited to, modeling of inhomogeneities such as joints, cracks, holes, and welds within a frame-like structure. Results from this method compare well with a full elastodynamic discretization and existing methods for modeling such problems.

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