A parametric study on patch repaired quasi‐isotropic laminate in high‐velocity impact environment: Experimental and numerical investigation

Abstract In this work, the post‐repair behavior of a quasi‐isotropic laminate was studied in a high‐velocity impact environment. The composite laminates were repaired using an external bonded patch repair procedure. Impact tests were performed to understand the effect of patch size and the result of filling the damaged region with a neat epoxy and hardener mixture. Two different size square patches, such as 30 and 50 mm, were used to analyze the effect of patch size. A continuum damage mechanics‐based model was developed and incorporated into a finite element model interface to estimate the optimum patch size and patch stacking sequence for the impact environment. In the finite element model, the intralaminar failure criteria were implemented using the ABAQUS‐VUMAT user subroutine, and the interlaminar failure criteria were implemented using the inbuilt cohesive contact properties. The 30 mm patch with resin filled in the damaged region performed better than the other combination patches. Also, placing 45° plies toward the outer layer of the patches showed lower damage compared to the patches in which 45° plies were placed at the inner surfaces. Highlights Post‐repair impact behavior of repaired laminates was examined. Impact of patch dimension and resin filling in the damaged area was analyzed. A 3‐D finite element model was developed to optimize patch parameters. Continuum damage mechanics model has been incorporated with VUMAT subroutine. Interface between lamina has been modeled using cohesive contact.