Structural integrity monitoring of composite patch repairs using wavelet analysis and neural networks

Author(s):  
Venkata K. Amaravadi ◽  
Kyle Mitchell ◽  
Vittal S. Rao ◽  
Mark M. Derriso
2018 ◽  
Vol 52 (30) ◽  
pp. 4203-4218 ◽  
Author(s):  
HN Maleki ◽  
TN Chakherlou

Aircraft repair is gaining importance for extending the service life of aging aircraft and also for improving its structural integrity. In this paper, a new repair method of aircraft structures is presented, and the performance of this method in mixed mode fracture has been evaluated and compared with other two repair methods by conducting experimental and numerical investigations. To do so, four batches of specimens were prepared and each of them subjected to five level of mixed mode loading using a modified version of Arcan fixture. Further, finite element simulations were utilized to find stress intensity factors to explain the experimental test results. The experimental results indicate that the hybrid repair method is the most effective method in terms of increasing fracture load and it was observed a significant increase in the tensile strength of the repaired parts by all three methods compared to the simple cracked samples. Repaired samples with the hybrid method, composite patch and bolt clamping exhibited up to 49%, 44%, and 24% increase in tensile strength under pure tensile mode respectively. However, in pure shear mode, the fracture strength increased to 28%, 18%, and 9% by the hybrid method, bolt clamping and composite patch respectively.


2015 ◽  
Vol 1120-1121 ◽  
pp. 670-674
Author(s):  
Abdelmadjid Ait Yala ◽  
Abderrahmanne Akkouche

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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