Patch repair design optimisation for fracture and fatigue improvements of cracked plates

Abstract

The problem of improving fracture and/or fatigue life of structural components by means of patch repairs is addressed in the present paper by applying a biology-based method, known as the Genetic Algorithm. The optimum design procedure consists in evaluating the patch topology, to be applied to the highest stressed region, which maximises the fracture resistance or the expected fatigue life of the improved structural component by keeping constant the total patched area (constrained optimisation problem). The proposed procedure is implemented in a finite element code and some numerical simulations are carried out in order to assess its reliability. The method is applied to two simple cases of cracked plates under pure Mode I or Mode II: for such analysed configurations, the method allow to improve significantly the fracture or fatigue behaviour of structural components repaired by employing the optimised shape patches instead of a simple shape (e.g. square or rectangular) patches.

Modeling of a cracked and repaired Al 2024T3 aircraft plate: effect of the composite patch shape on the repair performance

“…The repair of larger sizes cracks resulting in a negligible fluctuation of the SIF. This leads to say that, contrary to the results obtained by [17,18], when the overlapping surface of the cracked zone remains invariable, the patch shape has no T effect on the repair efficiency in terms of fracture energy reduction in mode I. In fact, the sharp edges (obtuse, right and acute) of these patch shapes, are positioned too far from the crack heads, which considerably reduces their effect of indefinitely storing normal stresses, strongly localised in this crack heads.…”

Optimization of Fiber-Reinforced Polymer Patches for Repairing Fatigue Cracks in Steel Plates Using a Genetic Algorithm

“…Kumar and Hakeem (2000) conducted a series of parametric FE studies to obtain the optimum patch shape that minimized the SIF of cracked aluminum sheets. Brighenti (2007) developed a tool in which a genetic algorithm (GA) was embedded in the FE code to obtain the patch topology that minimized the SIF of cracked steel plates. Errouane et al (2014) combined the FE method, response surface methodology (RSM), and gradient-based optimization to minimize the composite patch volume for cracked aluminum sheets.…”

A 3D analysis of crack-front shape of asymmetric repaired aluminum panels with composite patches

“…In particular, composite patch repair has shown its effectiveness in the field of aeronautics and maritime structures [1][2]. According to research, most studies address the problem of shape optimization, i.e the surface and the thickness of the patch [3][4][5][6][7][8][9][10]. Without omitting the effect of the parameters related to the adhesive such as the thickness and the type of the glue that have provoked several searches as for example in [11][12][13][14][15].…”