Study of composite patch repair by analytical and numerical methods

Abstract

A combined analytical and numerical study of an isotropic cracked plate that was repaired by using a bonded composite patch was conducted. The analytical work was based on Rose's equations, whereas for the numerical investigation a three‐dimensional finite element analysis was implemented. A number of cracked plates with different crack lengths and overall dimensions of the composite repair were considered. The composite patch was made of unidirectional laminates with different stacking sequences. Both, one‐ and two‐sided patches were analysed. Results are presented for the stress intensity factor in the patched crack and the maximum stress reinforcement stress and adhesive strain. It was found that for the case of a two‐sided reinforcement the results obtained by both methods were in good agreement. However, for the case of a single reinforcement the accuracy of the analytical method decreased due to the tendency to out‐of‐plane bending as a result of bonding a reinforcing patch to only one face of a plate, which is ignored in the analysis.

Two - Dimensional Finite Element Analysis of Composite Patch Repairs Using Shell Laminate Elements

“…The accuracy of the results computed by 3D FEA has already been verified both experimentally and against other numerical and analytical techniques in previous works [5,6]. Therefore, the results computed by 2D FEA using shell laminate elements will only be compared against 3D FEA.…”

“…However, because of the significantly different mechanical properties of the materials that form a composite patch repair (metals, composites and adhesives), its design usually requires the application of three-dimensional Finite Element Analysis (3D FEA), in order to adequately calculate the resulting stress field. Even though this kind of analysis has George J Tsamasphyros, George N Kanderakis, Nikos K Furnarakis and Zaira P Marioli-Riga proven to be reliable and accurate [5,6], it demands significant computer resources and remarkable modelling effort for its application. Therefore, alternative analysis methods have been proposed by various authors for certain repair cases, in order to reduce the modelling effort and the computational time [7,8].…”

Fatigue crack growth of composite patch repaired Al-alloy plates under variable amplitude loading

“…This technique offers significant advantages over traditional repair methods "riveting, fastening, and welding" [5]. In literature, several studies have investigated this technique, both numerical and experimentally, for different specimen's dimensions, and which have the following advantages: provides a high structural efficiency and extends the life of cracked structural components at an economical cost, and reduce the stress field near the crack, leads to retardation or complete arrest of the crack growth [3,[5][6][7], hence, as a result, crack growth is delayed and the service life of the repaired structures is extended. Fortunately, the presence of humidity presents harmful effect on fatigue behavior of adhesive joints bonded with aluminium [8].…”

Material parameter modeling and solution technique using birth–death element for notched metallic panel repaired with bonded composite patch

“…[1][2][3] Thus, adhesively bonded composite patch repairs to notched metallic substrate structure have received increasingly attention, and static and fatigue strengths of repaired metallic panels with the thin (less than 12.7 mm) and thick (more than 12.7 mm) thickness have been widely investigated. 4 Generally, thin panels were analyzed by using 2-D models, [5][6][7][8][9][10][11][12][13] whereas thick panels were done as a 3-D problem. [14][15][16][17][18][19][20][21][22][23][24] With thin panels, Naboulsi and Mall 5 proposed a 2-D model for the analysis of adhesive layer, composite patch and thin notched substrate panel.…”

“…Okafor et al 11 presented 2-D FE (finite element) model to simulate stress pattern of asymmetrically repaired panel with a central notch. Oterkus 12 and Tsamasphyros et al 13 took notched substrate panel, composite patch and adhesive layer as individual layers and adhesive layer was regarded as continuous elastomer to establish 2-D two-layer model for calculating stress intensity factor at crackle tip of repaired panel. Ouinas 14 considered notched substrate plate and adhesive layer as continuous elastomers and composite patch as orthotropic elastomer to simulate crack propagation process by means of 2-D two-layer model and J-integration criterion.…”