Computational characterization of adhesive layer properties using guided waves in bonded plates

This research develops a guided waves technique to nondestructively characterize the stiffness properties of bonded engineering components. This study first quantifies the influence of the relevant adhesive layer properties-Young's modulus, Poisson's ratio and bond thickness-on the dispersion curves of a two-layer bonded system, an aluminum plate with an adhesive tape layer bonded to its lower surface. Both a commercial finite element (FE) code (ABAQUS/Explicit) and the global matrix method (GMM) are used to determine the dispersion relationships of this bonded plate system in the form of frequency-wavenumber and slowness-frequency relations. These dispersion curves are then used to determine a set of adhesive tape parameter sensitive points, whose frequency coordinates represent the solution criteria for a proposed inversion procedure. This inversion is based on the GMM and assumes the three adhesive tape properties are unknown. The performance of this inversion procedure depends on the number of input time-domain signals; it is possible to solve the inverse problem for all three of the unknown adhesive tape properties if multiple input signals are known.