Fracture analysis of resistance welded L-shaped and straight sheets

A B S T R A C T In this paper, the finite element method is used to analyze the behaviour of repaired cracks in 2024-T3 aluminum with bonded patches made of unidirectional composite plates. The problem is considered in Mode I condition. First the K I stress intensity factor (SIF) is calculated by the finite element method using displacement correlation technique. Different plate and patch thicknesses and crack lengths are considered in the analyses.Then an equation is determined by using genetic algorithms for the calculation of stress intensity factor without any further finite element analysis. The equation gives reasonably accurate results.Keywords finite element analysis; genetic algorithm approach; patched crack; stress intensity factors. N O M E N C L A T U R Ea = crack length E = modulus of elasticity GAPD = genetic algorithm patch design K I = stress intensity factor for mode I condition K IP = SIF for patched condition K IC = fracture toughness p = patch thickness R 2 = coefficient of determination SIF = stress intensity factor t = aluminum thickness t a = adhesive thickness w = aluminum plate width v = poisson ratio σ = applied stress I N T R O D U C T I O NIn aircraft structures, traditional repair methods such as bolt and rivets cause stress concentration due to drilling of additional fastener holes. Therefore, the development of bonding technology has been accelerated. Adhesively bonded repairs cause minimum stress concentration and alter the load path that induces efficient load transfer from cracked structure to reinforcement. Thus, the reduction of the stress intensity factor caused by bonded patch repair prevents or retards crack re-initiation or further growth.The bonded patch offers many advantages over mechanically fastened doublers, which include improved fatigue behaviour, reduced corrosion and easy conformance to complex aerodynamic contours. 2,3 Baker pioneered studies about bonded composite repairs in aircraft and marine structures, most of which have been focused on Mode I opening of crack. Megueni et al. 4 used the finite element method to compute the stress intensity factor for repairing cracks with bonded composite patches taking account of the disbond. In the case of disbond, the increase of patch thickness reduces the negative effects of disbond. Tsai and Shen 5 performed stress analyses for four different aluminum plates, including no crack, with crack, with

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“…It can be seen from Fig. 1 that the patch prevents a significant increase of SIF, as observed in previous studies 4,13,19 …”

Section: Resultssupporting

confidence: 85%

“…1 that the patch prevents a significant increase of SIF, as observed in previous studies. 4,13,19 The patched SIF value (K IP ) is given in a normalized form in Fig. 6 by dividing it by the unpathched SIF value (K I ) to show the considerable effect of the patch.…”

Section: Variations Of Sif In Patched and Unpatched Platesmentioning

confidence: 99%

Determination of SIF for patched crack in aluminum plates by the combined finite element and genetic algorithm approach

Ergun

Taşgetiren

Topçu

2008

Fatigue Fract Eng Mat Struct

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“…However, welds often exhibit defects such as porosity, inclusions, and voids [3,4], which are influenced by factors including the chemical composition of the materials and welding conditions. The weld profile's shape results in high stress concentrations, leading to crack initiation and propagation under static or cyclic loading until the weld bead fractures [3][4][5]. Consequently, the failure behavior of welded structures has been extensively investigated in recent years.…”

Section: Introductionmentioning

confidence: 99%

Effect of Porosity Shape, Size and Distribution on Stress Intensity Factors in Spot Welded Joints: A Finite Element Study

Benala,

Zouambi,

Bouafia

et al. 2023

ACSM

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In this study, the influence of porosity on crack initiation behavior in welded structures subjected to spot welding was investigated. Three-dimensional (3D) finite element analyses were conducted using the ABAQUS finite element software under mechanical stress. The stress intensity factors (SIF) in opening and moving modes were computed employing the finite element technique. A comprehensive analysis of various parameters, including mechanical load, crack size, porosity form, porosity size, porosity-crack interaction, and crack orientation, was carried out. This investigation was approached as a mixed-mode, plane stress, and linear elastic fracture mechanics problem with a focus on the passive voice. The results demonstrated that the stress intensity factor is not only dependent on the magnitude of the applied mechanical loading but also on factors such as crack size, porosity form, defect-defect interaction, and crack orientation. Additionally, it was observed that both the size and form of porosity play a significant role in influencing the stress intensity factors. This research contributes to the understanding of fracture mechanics in welded structures and provides valuable insights for enhancing the structural integrity and reliability of such systems.

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3-D finite element analysis of stress concentration factor in spot-welded joints of steel: The effect of process-induced porosity

Bouafia¹,

Sérier²,

Amin³

et al. 2011

Computational Materials Science

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Fracture analysis of resistance welded L-shaped and straight sheets

Cited by 8 publications

References 15 publications

Determination of SIF for patched crack in aluminum plates by the combined finite element and genetic algorithm approach

Determination of SIF for patched crack in aluminum plates by the combined finite element and genetic algorithm approach

Effect of Porosity Shape, Size and Distribution on Stress Intensity Factors in Spot Welded Joints: A Finite Element Study

3-D finite element analysis of stress concentration factor in spot-welded joints of steel: The effect of process-induced porosity

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