Abstract In this paper, experimental and numerical buckling studies of adhesively bonded carbon/epoxy laminates with closed debonds are investigated. To know the effect of debonds on the load bearing capability of bonded composite laminates, two sets of studies are attempted. First, the carbon fibre reinforced (CFRP) laminates are fabricated and adhesively bonded together without any artificial debonds, secondly the closed artificial debonds of desired sizes are introduced. Studies are carried out to analyze the effect of these debonds on load bearing capacity. For the experimental studies, quasi-isotropic CFRP specimens are realized with and without artificial debonds and the buckling loads are obtained from the experiment with clamped and free boundary conditions at the loading and the non-loading edges respectively. The specimens are found to exhibit a plate-column mode of buckling. Commercially available finite element package, MSC/NASTRAN has been used for numerical analysis. The experimental and numerical loads are compared and it reveals that close correlation exits between them. From the numerical analysis, it is observed that buckling load decreases when the debond size increases.
In this paper, the effects of the delaminations size on the critical buckling load and compressive failure load of E-glass/epoxy composite laminates with multiple large delaminations are studied. A numerical and experimental study is carried out to determine the buckling load of rectangular composite plates. For the experiments (0°/90°/0°/90°)s oriented cross-ply laminated plates with multiple large delaminations and without delamination are produced by using hand lay-up technique. The experimen...
Abstract The strains at which buckling and debond growth occur in adhesively bonded composite flanges containing an initial debond were experimentally measured. Test parameters including initial debond geometry, flange material stiffness, and the adhesive critical strain energy release rate ( G c ) were investigated. Debond growth was found to be strongly dependent on initial debond length but weakly dependent on flange width; i.e., debonding resistance did not increase in direct proportion with...
Last. Sami Aksoy(Dokuz Eylül University)H-Index: 7
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The effect of a single circular delamination around the circular hole on the critical buckling load of woven fabric laminated composite plates has been investigated experimentally and numerically. The determination of the critical delamination diameter for laminated composite plates has been intended by using three dimensional buckling analysis. For the experiments, cross-ply laminated composite plates with delamination and without delamination have been produced. The experimental critical buckl...
Last. Martyn J Pavier(UoB: University of Bristol)H-Index: 33
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Delaminations cause a reduction in the compressive strength of a composite material and multiple delaminations cause greater strength reduction than single ones. Since realistic damage such as that resulting from an impact consists of multiple delaminations, it is of interest to understand the mechanism of strength reduction for laminates containing multiple delaminations. In this work, compression testing of glass fibre reinforced plastic specimens containing single and multiple embedded delami...
This paper contributes newly developed closed-form buckling solutions for generic one-edge-free problems common to partially disbonded composite structures. These solutions are shown to be accurate by comparison with experimentally measured buckling loads which are also reported in this paper. The buckling of partially disbonded regions in adhesive joints is a safety concern due to the potential for ensuing buckling-driven disbond growth. In order to design structures to be tolerant to these fla...
Buckling-driven disbond growth in adhesivelybonded flange configurations having one-edge-free boundary conditions was investigated from both theoretical and experimental perspectives. The objective of this paper is to provide predictive capability for this type of problem, and to validate the predictions by experiments. The closed-form theoretical model is shown to be accurate when predicting both buckling and disbond growth initiation strains, as measured by tests on composite splice jointed sa...
Last. Martyn J Pavier(UoB: University of Bristol)H-Index: 33
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Abstract Delaminations reduce the compressive strength of composite laminates because they allow out of plane displacement of plies to occur more easily. This work is a study of the effect of delaminations in laminates with initial curvature. Initial curvature typically results in an increased buckling load and the hypothesis was that the reduction in compressive strength due to delamination would be less in a curved specimen than a flat one. Glass fibre reinforced plastic test laminates were ma...
Abstract A comprehensive finite element (FE) analytical tool to predict the effect of defects and damage in composite structures was developed for rapid and accurate damage assessment. The structures under consideration were curved, T-stiffened, multi-rib, composite panels representative of those widely used in aerospace primary structures. The damage assessment focussed on skin-to-stiffener debonding, a common defect that can critically reduce the performance of composite structures with integr...
#1Hyonny Kim(UCSB: University of California, Santa Barbara)H-Index: 4
#2Keith T. Kedward(UCSB: University of California, Santa Barbara)H-Index: 12
An analytical methodology is presented for predicting the buckling initiation of delaminated composite plates. Both global and local sublaminate buckling deformation modes are predicted for rectangular plates of any thickness. The global behavior of the delamination zone is accounted for by summing the individual stiffness contributions of each sublaminate constituting the delamination zone. This allows for the delamination zone to be treated as a single plate when performing global buckling pre...
#1V. V. Bolotin(RAS: Russian Academy of Sciences)H-Index: 9
The most up-to-date research in the mechanics of delaminations and related crack-like defects in laminate and fiber composites is discussed. Both internal and near-surface delaminations are considered. In the latter case, local buckling of delaminations and the interaction between buckling, damage accumulation, crack growth and global buckling are considered. The problem of the evaluation of the residual load-carrying capacity of delaminated structural components is discussed, including the asse...
Last. Chang Liu(Tianjin Polytechnic University)H-Index: 4
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Abstract Ultrasonic high-frequency vibration can effectively improve the fluidity of adhesive thereby allowing adhesive to fully and more evenly permeate the surface structure of composite laminates. This effect can enhance the mechanical properties of composite adhesive bonding joints. In this study, carbon fiber reinforced epoxy (CFRE) composite laminates were used as the substrate and different ultrasonic vibration-assisted preprocessing time and power are considered. The results show that fo...
#1K. Senthil(VSSC: Vikram Sarabhai Space Centre)H-Index: 4
#2A. Arockiarajan(Indian Institute of Technology Madras)H-Index: 16
Last. R. Palaninathan(Indian Institute of Technology Madras)H-Index: 10
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Abstract Experimental studies and numerical simulations are performed to investigate the structural response of adhesively bonded CFRP cylindrical splice-joint panels subjected to axial compression. Splicer joints used in aerospace composite structures need to sustain the design ultimate loads in the presence of flaws due to manufacturing (debonds), in order to demonstrate compliance with flightworthiness. CFRP cylindrical splice-joint specimens with and without debonds are subjected to compress...
#1K. Senthil(VSSC: Vikram Sarabhai Space Centre)H-Index: 4
#2A. Arockiarajan(Indian Institute of Technology Madras)H-Index: 16
Last. R. Palaninathan(Indian Institute of Technology Madras)H-Index: 10
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Carbon fiber-reinforced polymer structures are being increasingly used in aerospace applications. In this work, analytical, numerical, and experimental investigations are carried out to understand the structural response of debonded carbon fiber-reinforced polymer splice joint subjected to compression load. It is found that debonds are of major importance for the behavior of carbon fiber-reinforced polymer splice-joint structures. A series of carbon fiber-reinforced polymer splice-joint specimen...
#1K. Senthil(VSSC: Vikram Sarabhai Space Centre)H-Index: 4
#2A. Arockiarajan(Indian Institute of Technology Madras)H-Index: 16
Last. K.M. Usha(VSSC: Vikram Sarabhai Space Centre)H-Index: 3
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Abstract This present work aims to investigate the effect of debonds on the structural performance of adhesively bonded curved carbon fiber reinforced plastic (CFRP) panels under compressive loading environment. Representative curved panels are fabricated with a quasi-isotropic lay-up. Two types of specimens are prepared for the studies, one without debonds and the other with debonds of specified size, artificially introduced within the lap region. Pulsed thermography non-destructive technique i...
In this study, an elastic–plastic stress analysis is carried out in fiber glass-epoxy adherends with DP460 ductile adhesive. Multi-linear plastic solution is applied to the joints. Analytical results are checked using a multi-linear finite element solution, ANSYS 12. Analytical and numerical solutions are found to be in good agreement. The thickness of the adherend is chosen as 1.8 mm, 2.5 mm and 3 mm. It is observed that when the thickness of the adherend is increased, the intensity of the peel...
#1K. Senthil(VSSC: Vikram Sarabhai Space Centre)H-Index: 4
#2A. Arockiarajan(Indian Institute of Technology Madras)H-Index: 16
Last. K.M. Usha(VSSC: Vikram Sarabhai Space Centre)H-Index: 3
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Abstract The principal aim of this paper is to present a comprehensive literature survey on the defects, like debonds/delamination in composite joints/structures, focusing on the effect of defects, its growth initiation and prediction methods in fibre reinforced plastics. The effects of delaminations, its size, shape and position have been extensively studied over the past few decades. Very little attention has been paid in the area of adhesively bonded joints with closed debonds. The phenomena ...