Repairability of Impact-Induced Damage in SMC Composites

This study discusses the repairability of impact-induced damage in an SMC composite which is made of chopped glass fibers and polyester matrix. The impact resistance and notch sensitivity of the composite material are characterized by tensile and flexural tests. Equivalent hole sizes for impact-induced damage are identified through the comparisons between the residual strengths of composites with impact-induced damage and artificial circular cutouts. It is concluded that no damaged portion should be removed from the impacted composites; otherwise more damage could be introduced to the com posites. The damaged composites are then repaired with a technique combining resin in jection and reinforcing patches. The resin injection is performed to seal the matrix cracks which would otherwise result in high stress concentrations due to geometrical discon tinuity. The reinforcing patches are employed to compensate for the strength reduction due to fiber breakage. It is revealed from the experiments that the repair technique is very effi cient for restoring the tensile and flexural strengths of the composite after impact-induced damage.