Electromagnetic modeling of damaged fiber-reinforced laminates

Abstract : As a prerequisite to nondestructive testing of damaged fibered laminates, theGreen’s function, corresponding with an undamaged structure, and the electromagneticfields associated with the damaged one are investigated herein.For the undamaged fibered laminate, benefiting from the periodicity of thefibers within each layer, the field solution follows the scattering-matrix-basedmethod using the Floquet theorem. Yet, the periodicity is destroyed by theanalytical source (for the Green’s function) or by damages, and the Floquettheorem cannot be directly applied to compute the associated scattering matrices.The array scanning method is introduced to that effect. Inserting fictitioussources to get a quasi-periodic source array, the modeling approach for undamagedlaminates can be used to compute the field with the source array, theintegration of which cancels the effects of the fictitious sources and yields theGreen’s function. With the multipole method, field disturbances by damages,which include missing, displaced, shrunk, and expanded fibers and circularinclusions inside fibers, are accurately modeled by setting equivalent sourcesinside sound fibers, and the array scanning method applies. Modeling accuracyand efficiency of the approaches are illustrated by numerical simulations.