5xxx Aluminum Sensitization and Application of Laminated Composite Patch Repairs

The aim of this work is to define a general method for the optimization of composite patch repairing. Fracture mechanics theory shows that the stress intensity factor tends towards an asymptotic limit K∞.This limit is given by Rose’s formula and is a function of the thicknesses and mechanical properties of the cracked plate, the composite patch and the adhesive. The proposed approach consists in considering this limit as an objective function that needs to be minimized. In deed lowering this asymptote will reduce the values of the stress intensity factor hence optimize the repair. However to be effective this robust design must satisfy the stiffness ratio criteria. The resolution of this double objective optimization problem with Matlab program allowed us determine the appropriate geometric and mechanical properties that allow the optimum design; that is the selection of the adhesive, the patch and their respective thicknesses.

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Flutter of Perforated Metallic Plates Repaired with Cross-Ply Composite Patches

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.417-418.709 ◽

2009 ◽

Vol 417-418 ◽

pp. 709-712

Author(s):

Ali Amin Yazdi ◽

Jalil Rezaeepazhand

Keyword(s):

Laminated Composite ◽

Material Anisotropy ◽

Perforated Plates ◽

Closed Form Solutions ◽

Finite Element Software ◽

Composite Patch ◽

Numerical Studies ◽

Flutter Analysis ◽

Flutter Boundary ◽

Metallic Plates

This study investigates the application of laminated composite patches for enhancement of flutter behavior of perforated metallic plates repaired with an external composite patch. Due to material anisotropy and discontinuity in geometry involved in flutter analysis of repaired plates, closed form solutions are practically unobtainable. Numerical studies using commercial finite element software were conducted to investigate the effects of variation in lamination parameters on the flutter boundary of perforated plates repaired with cross-ply composite patches. Both ply-level and sub-laminate level configurations are investigated. Presented results illustrate that flutter boundaries of perforated plates can be changed by choosing proper stacking sequence for composite patches.

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A review on composite patch repairs and the most important parameters affecting its efficiency and durability

Journal of Reinforced Plastics and Composites ◽

10.1177/0731684420941602 ◽

2020 ◽

pp. 073168442094160

Author(s):

Sirvan Mohammadi ◽

Mohammad Yousefi ◽

Mahdi Khazaei

Keyword(s):

Residual Stress ◽

Service Life ◽

Fatigue Behavior ◽

Composite Patch ◽

Mechanically Fastened ◽

Patch Repairs ◽

Adhesive Thickness ◽

Patch Length

In many industries, when replacement of a part is not possible or economic, the repair is done. One of the best methods for repairing metal and composite parts is using composite patches. Repairing with a composite patch is a widespread field to extend the service life of the cracked components. This technique is more structurally efficient with fewer damages on the structure than others. The bonded patch offers many advantages over a mechanically fastened doubler, which include improved fatigue behavior, reduced corrosion, and easy conformance to complex aerodynamic contours. In this article, advantages of the composite patch and its efficiency and durability are discussed, and the most important parameters (patch and adhesive thickness, patch separation, residual stress, patch length and width, etc.) affecting its performance are studied based on the latest available references.

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