The optimization thickness of single/double composite patch on the stress intensity factor reduction

2013 ◽  
Vol 32 (9) ◽  
pp. 654-663 ◽  
Author(s):  
Djamel Ouinas ◽  
Belkacem Achour ◽  
BelAbbes Bachir Bouiadjra ◽  
Noria Taghezout
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Composite Patch

General Method for Optimizing Composite Patch Repairs

2015 ◽  
Vol 1120-1121 ◽  
pp. 670-674
Author(s):  
Abdelmadjid Ait Yala ◽  
Abderrahmanne Akkouche
Keyword(s):  
Mechanical Properties ◽  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Optimization Problem ◽  
Composite Patch ◽  
Matlab Program ◽  
Patch Repairs ◽  
Selection Of ◽  
General Method

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.

scholarly journals Finite element method investigation of geometrical influences of adhesive and patch in the safety for 90° elbow piping system

2019 ◽  
Vol 13 (4) ◽  
pp. 5973-5987
Author(s):  
Ibrahim Gadi ◽  
Madjid Meriem-Benziane ◽  
B. Bachir Bouiadjra
Keyword(s):  
Finite Element Method ◽  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Three Dimensional ◽  
Operating Conditions ◽  
Piping System ◽  
Composite Patch ◽  
Circumferential Crack ◽  
Pipeline Safety

Piping system elbow study is the most important part in all fields of hydrocarbons transportation which presents the behaviour of circumferential crack at elbow extrados. The effect of geometry of adhesive and patch in the crack elbow is important in pipeline safety. This study shows the details for along the direction of the circumferential elbow crack by three dimensional (FEM) which is used to determine the stress intensity factor at 90° elbow for two cases: firstly, without patch and secondly, repaired with composite patch. This method allows to predict the behaviour of cracked elbow through the analysis of crack propagation under the internal different pressures taking into consideration the operating conditions. The geometry and nature of composite patch proved   that the increase of patch thickness leads to decrease the SIF from 7 MPa.m1/2 to 6.15 MPa.m1/2. It can be concluded that the repairing by composite materials leads to reduce the stress intensity factor with patch which not only can augment the lifetime of pipeline but also decreasing the costs and the pollution.

Stress intensity factor for repaired crack with bonded composite patch under thermo-mechanical loading

2011 ◽  
Vol 30 (5) ◽  
pp. 416-424 ◽  
Author(s):  
R. Mhamdia ◽  
B. Bachir Bouadjra ◽  
B. Serier ◽  
W. Ouddad ◽  
X. Feaugas ◽  
...  
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Mechanical Loading ◽  
Composite Patch ◽  
Bonded Composite

Numerical Analysis of Asymmetrically Bonded Composite Patch Repair and Effect of In-Plane Skewed Crack Front on the SIF

2017 ◽  
Vol 30 ◽  
pp. 11-22 ◽  
Author(s):  
Baltach Abdelghani ◽  
Aid Abdelkarim ◽  
Abdelkader Djebli ◽  
Belabbes Bachir Bouiedjra ◽  
Benhamena Ali
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Crack Growth ◽  
Crack Front ◽  
Patch Repair ◽  
Growth Stages ◽  
Initial State ◽  
Element Analysis ◽  
Composite Patch

A nonlinear 3-D finite element analysis was conducted to analyze the crack front behavior of a center cracked aluminum plate, asymmetrically repaired with composite patch. According to experimental observations, the crack front was modeled as an inclined shape from the initial state where the crack front is straight and parallel to the thickness direction from the patched side toward the un-patched side. The skew degree is found to strongly influence the stress intensity factor (SIF) distribution along the crack front. In effect, the obtained trends of the SIF’s distribution are different and changes during crack growth stages. The main finding is that regardless the crack front shape (inclination), the average stress intensity factor through the crack front remains constant and consequently, it means to be an effective parameter to estimate the fatigue life and crack growth of the asymmetrically patched structures. The performed models gave good results compared to the literature and the different findings correlate well with the experimental observations and make sense with a realistic crack development.

Numerical analysis of cracked aluminum plate repaired with multi-scale reinforcement composite patches

2020 ◽  
Vol 54 (28) ◽  
pp. 4341-4357
Author(s):  
A Yousefi ◽  
M Mosavi Mashhadi ◽  
M Safarabadi
Keyword(s):  
Mechanical Properties ◽  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Cohesive Zone Model ◽  
Volume Fraction ◽  
Aluminum Plate ◽  
Zone Model ◽  
Composite Patch ◽  
Different Thickness

In this study, numerical modeling is used to investigate the performance of a single-sided composite patch with different scale fillers, as reinforcement of a cracked aluminum plate under static tension. The main concerns of previous studies are about the geometry of patches, composite layups, and failure of adhesive. In this research, the effect of patch properties such as size and fiber volume fraction, the thickness of patch, and thickness of adhesive on the overall performance of the cracked aluminum plate are investigated numerically. Indeed, first, a 3 D representative volume element (RVE) is adopted to calculate the mechanical properties of carbon nanotube (CNT)/epoxy and carbon fiber (CF)/epoxy composite patch at each specified volume fraction for investigating the effect of patch properties on the performance of a single-sided patch for crack repairing. In this regard, the cohesive zone model is adopted to analyze the debonding between the epoxy matrix and reinforcement to characterize the mechanical properties of composite patches. Finally, a linear 3 D finite element analysis is performed to calculate the stress intensity factor (SIF) for cracked aluminum plate repaired by a single-sided composite patch at each specified reinforcement volume fraction for different thickness of patch and different thickness of adhesive. The results demonstrated that the stress intensity factor highly depends on the patch properties (patch stiffness) in addition to patch thickness and adhesive thickness.

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