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A perfectly matched layer (PML) absorbing boundary is formulated for and numerically applied to peridynamics in two dimensions. Peridynamics is a nonlocal method, derived to be insensitive to discontinuities, more easily simulating fracture. A PML is an absorbing boundary layer, which decays impinging waves exponentially without introducing reflections at the boundary between the computational region and the absorbing layer. Here, we use state-based peridynamics as PMLs are essentially anisotropic absorbing materials, therefore requiring arbitrary material parameters. State-based peridynamics is also more convenient for auxiliary field formulations, facilitating the implementation of the PML. Results show the efficacy of the approach.

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This paper describes the use of genetic algorithms (GAs) for the optimal design of phononic bandgaps in periodic elastic two-phase media. In particular, we link a GA with a computational finite element method for solving the acoustic wave equation, and find optimal designs for both metal-matrix composite systems consisting of Ti/SiC, and H 2 O-filled porous ceramic media, by maximizing the relative acoustic bandgap for these media. The term acoustic here implies that, for simplicity, only dilatational wave propagation is considered, although this is not an essential limitation of the method. The inclusion material is found to have a lower longitudinal modulus (and lower wave speed) than the surrounding matrix material, a result consistent with observations that stronger scattering is observed if the inclusion material has a lower wave velocity than the matrix material.