Fast Approximation of Wave Propagation in Complex Geometries

Abstract

A minimal model to approximate wave propagation in complex structures has been proposed in previous works of the authors. Core principle of the model is a reduction of inhomogeneities, like stiffeners, to interaction parameters and homogeneous areas to phase velocities. Combined with the plate like shape of aircraft parts relevant for SHM, a two-dimensional model is sufficient to simulate these structures. Paths taken by the waves from actuator to sensor are estimated with ray tracing. Finally, signals at selected sensor positions can be calculated with a signal synthesis algorithm. Several characteristic values of the structure significant to guided waves have to be calculated beforehand. Preparation of such a database can be costly to a certain extent, but is only necessary once per part. With a database in place, the proposed technique offers a very fast way to approximate wave propagation in large and complex structures. This paper discusses effects that influence wave propagation, sensor signals and simulation accuracy. To validate the model, measured signals and FEM solutions are compared to results of the minimal model.