Dynamic response of a repaired composite beam with an adhesively bonded patch under a harmonic peeling load

The dynamic response of repaired composite beams under a harmonic peeling load was studied theoretically and experimentally. The repair method was based on removal of the damaged region and bonding a composite patch into the gap with adhesive. In the theoretical part, the equations of motion in the axial and transverse directions were derived assuming that the viscoelastic adhesive layer resists both peeling and shear stresses and both the patch and parent materials behave as Euler-Bernouli beams. The validity of the theoretical model for evaluating the dynamic response of repaired composite beams was examined with the results of the finite element model. The finite element results indicated that the deformation mechanism of the repaired composite beam depends on the adhesive elastic modulus. For low values of the adhesive elastic modulus, shear deformation in the adhesive layer is the dominant deformation mechanism and the proposed theoretical model replicated the results of the computational analysis. In the experimental part, the response of unidirectional fiberglass-reinforced epoxy composite specimens with various repaired patch lengths, thickness, and material properties were measured by hammer test technique using a non-contact laser vibrometer. The patch section was either the fiberglass-reinforced epoxy composite or E-glass fiber reinforced composites with various stacking sequences. The repairing patches were bonded to the composite beam with an epoxy. The experimental results were compared to those of the theoretical model and finite element analyses. The experimental results were related to the adhesive material properties, its loss factor and to the patch material properties. (C) 2005 Elsevier Ltd. All rights reserved.