Modelling the effects of patch-plug configuration on the impact performance of patch-repaired composite laminates.

The patch-plug configuration has been widely used to repair composite structures and restore the structural integrity of damaged composites. In the present research, single-sided CFRP patch-repaired panels, with different patch-plug configurations, are prepared. This is where a circular-shaped damaged area has been removed and a CFRP patch has been adhesively-bonded onto the panel. In some cases, a CFRP plug is inserted into the hole, caused by removal of the damaged area, before the patch is applied. Such patch-repaired panels, and the pristine CFRP panel, are subjected to a low-velocity impact at an energy of 7.5 J. These impacted pristine and repaired panels are then examined using ultrasonic C-scan and optical microscopy to inspect the impact-associated permanent indentation, interlaminar and intralaminar damage. A finite element analysis (FEA) model, which significantly extends a previously validated elastic-plastic (E-P) numerical damage model, has been developed to predict the impact behaviour of the pristine CFRP panel and the various designs of patch-repaired CFRP panels. The comparison between the experimental and numerical results for all the studied cases shows the maximum deviations for the loading response and the damage area are 12% and 15%, respectively. The good agreement between the experimentally-measured impact properties and those predicted using the numerical model demonstrates that the model is a useful design tool. [Display omitted] • Pristine CFRP panels and Single-sided CFRP patch-repaired panels with and without plugs are prepared and impacted at an energy of 7.5 J; • Effects of the diameter and thickness of the patch as well as the presence of plug on the impacted behaviour of repaired composites are investigated; • Good correlation, between the experiment and simulation demonstrates that the developed numerical model is a useful design tool; • The results revealed that the patch thickness has larger effects on the impact behaviour of repaired composites compared to the patch diameter; • A plug can provide added structural integrity to a composite repair and reduce damage in the adhesive bond. [ABSTRACT FROM AUTHOR]