A Study on the Best Conventional Shapes for Composite Repair Patches

Abstract

Adhesively bonded repair patches are an excellent approach for repairing locally damaged composite components. If correctly applied, fiber-reinforced patches may restore/increment the mechanical response of damaged laminates without significantly increasing the structure's mass or altering its geometry. However, in order to take full advantage of this repairing technique, one must employ patches with a minimal surface area and maximum efficiency in incrementing the strength of the component. The present work aims to study optimum-based patch shapes for conventional repair geometries, namely rectangular and elliptical. Shell Finite Elements models were used to simulate a parent plate, which is a rectangular flat laminate with a central trespassing damage region. Unbalanced single-ply patches were modeled on the upper surface of the damaged laminate. The patches' efficiency was computed as its capability in restoring the modal response of the repaired component to its undamaged configuration. Sequential linear programming was employed alongside shell finite element models to obtain optimal geometrical parameters for the patches' shape. The study cases comported two different boundary conditions and two stacking sequences. The optimum-base repair patches were defined regarding size and fiber orientation angle.

Elliptical one-side composite bonded repair analysis through a differential evolution algorithm

“…Despite the above-mentioned knowledge, maintenance engineers establish the topology and thickness of composite adhesively bonded repairs by trial and error, which results in uncertainties about the performance of the repair and the lack of a systematic procedure to determine the optimal dimensions of the patch. Several patch optimization procedures have been proposed (Bouchiba and Serier, 2017;Brighenti et al, 2006;Echer et al, 2021;Kashfuddoja and Ramji, 2014;Mahadesh Kumar and Hakeem, 2000;Ramji et al, 2013). However, these procedures do not consider the asymmetrical stress distribution in the single-sided patch repair; moreover, the resultant shapes Figure 1 Schematic representation of the stress distribution in (a) one-side patch, where a bending moment is introduced, and (b) double-side patch in most cases are too complex to be suitable for practical applications.…”

Patch Repair Analysis of Impact Damaged Glass Fiber / Epoxy Composite Tubes Operating Under Internal Pressure

“…Instead of regular square or rectangular patch, an optimal shape patch has reduced SIF and eventually increased mechanical properties by keeping the patch area constant. Also, a recent study was performed by Echer et al [10] who applied fiber reinforced patches to locally damaged composite parts. The research was aiming to define optimum sized and fiber-oriented patches for conventional rectangular and elliptical geometries.…”