Delamination Phenomenon in Composite Laminated Plates and Beams (original) (raw)
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A Review Study of Delamination in Composite Laminated Decks Plates
2020
Failure analysis of laminated composite decks structures has attracted a great deal of interest in recent years due to the increased application of composite materials in a wide range of high-performance structures. Intensive experimental and theoretical studies of failure analysis and prediction are being reviewed. Delamination, the separation of two adjacent plies in composite laminates, represents one of the most critical failure modes in composite laminates. In fact, it is an essential issue in the evaluation of composite laminates for durability and damage tolerance. Thus, broken fibers, delaminated regions, cracks in the matrix material, as well as holes, foreign inclusions and small voids constitute material and structural imperfections that can exist in composite structures. Imperfections have always existed and their effect on the structural response of a system has been very significant in many cases. These imperfections can be classified into two broad categories: initial...
A REVIEW STUDY OF DELAMINATION IN COMPOSITE LAMINATED PLATES
A REVIEW STUDY OF DELAMINATION IN COMPOSITE LAMINATED PLATES, 2019
Failure analysis of laminated composite structures has attracted a great deal of interest in recent years due to the increased application of composite materials in a wide range of high-performance structures. Intensive experimental and theoretical studies of failure analysis and prediction are being reviewed. Delamination, the separation of two adjacent plies in composite laminates, represents one of the most critical failure modes in composite laminates. In fact, it is an essential issue in the evaluation of composite laminates for durability and damage tolerance. Thus, broken fibers, delaminated regions, cracks in the matrix material, as well as holes, foreign inclusions and small voids constitute material and structural imperfections that can exist in composite structures. Imperfections have always existed and their effect on the structural response of a system has been very significant in many cases. These imperfections can be classified into two broad categories: initial geometrical imperfections and material or constructional imperfections.
Interlaminar failure investigations on delamination growth of composite laminates
IOP Conference Series: Materials Science and Engineering, 2019
The investigation of the interlaminar damage evolution on multi-layered composites as well as the numerical modelling techniques available for the simulation of the interface delamination are still a current concern. The complexity of modelling the mechanical behaviour and fracture modes of composite laminates is increased because of the anisotropic behaviour of the material, the fibre arrangement or other important parameters, such as stacking sequence, fibre orientation angle and the configuration of the composite laminates. Different failure modes may occur on multi-layered composites, which can lead to significant stiffness and strength reduction or to the complete loss of the load carrying capacity. The interlaminar stresses are the main factors responsible for the initiation and growth of the interlaminar failures such as delamination. They may occur as a result of manufacturing defects, low-velocity impacts or as an effect of the presence of the free edges. The delamination o...
Numerical and analytical study of delamination in composite laminates
2012
A robust numerical method is developed to study delamination in composite beam structures under lateral and axial loads. A tensor symmetrisation technique is used to formulate the beam element based on the Euler beam theory with full geometrical non-linearity to achieve high computational efficiency. Ply interfaces are modelled with high-stiffness springs. It is found that the beam element suffers from membrane locking for non-symmetric laminates. A method is found to overcome it. The model is used to simulate double cantilever composite beam structure tests and end notched flexure tests. Excellent agreement is observed with analytical and existing numerical and experimental data. The model is also used to study the buckling, post-buckling and delamination propagation in moderately thick composite beams. Satisfactory agreement is demonstrated between the present predictions and existing numerical and experimental data. It is noted that the through-thickness shear effect is significant for moderately thick composite laminates.
Application of a delamination model to laminated composite structures
Composite Structures, 2002
A model for progressive interlaminar delamination is presented for laminated composite structures. Instead of a cumbersome 3D description, a computationally efficient 2D technique is adopted which models the laminated structure as an assembly of sublaminates connected through their interfaces. Constraints between sublaminates are removed to represent the presence of delaminations. The use of laminate theory results in jumps in stress resultants across the delamination tip and this helps to avoid dealing with the singular stress field at the delamination front. A stress-based failure criterion is used to predict delamination initiation. Delamination propagation is analysed by adopting a fracture mechanics approach. The major intralaminar damage mode, matrix cracking, is also included in the present analysis. This is detected by a stress-based failure criterion and a ply discount model is used to account for the effects of material degradation. Finite element analysis has been carried out to assess the deformation and the delamination development in a range of typical structures: a double cantilever beam, a cross-ply laminate and some filament-wound composite pipes. Good agreement has been achieved between the predictions and available experimental data. A study of the effect of mesh size shows that a relatively coarse mesh gives sufficiently accurate results. These examples give a useful indication of the versatility and feasibility of the present approach for real structural applications.
Numerical Analysis of Delamination Effects on Laminated Composites
A composite is a structural material which consists of combining two or more constituents. Composites have lot of advantages like high stiffness-to-weight ratio, high strength-to-weight ratio, non corrosive, high fatigue-life etc. Composite materials are classified into fibrous composite materials, particulate composite materials and laminated composite materials. Laminated composite materials consist of layers of at least two different materials that are bonded together. Composite laminates are widely used in different areas due to their easy fabrication and effectiveness. Despite of their benefits composite materials have their disadvantages. Delaminations are the common damages in laminated composites. Delamination means separation of laminate at the interface between two layers. In the present study deals with the numerical analysis of delamination effects on laminated composites using ANSYS software. Various parameters such as delamination length and locations, multiple delaminations are studied.
A Delamination Propagation Model for Fiber Reinforced Laminated Composite Materials
Mathematical Problems in Engineering, 2018
The employment of composite materials in the aerospace industry has been gradually considered due to the fundamental lightweight and strength characteristics that this type of materials has. The science material and technological progress reached matched perfectly with the requirements for high-performance materials in aircraft and aerospace structures; thus, the development of primary structure elements applying composite materials became something very convenient. It is extremely important to pay attention to the failure modes that influence composite materials performances, since these failures lead to a loss of stiffness and strength of the laminate. Delamination is a failure mode present in most of the damaged structures and can be ruinous, considering that the evolution of interlaminar defects can carry the structure to a total failure followed by its collapse. The present work aims at the development of a delamination propagation model to estimate a progressive interlaminar d...
Delamination tolerance studies in laminated composite panels
Sadhana, 2000
Determination of levels of tolerance in delaminated composite panels is an important issue in composite structures technology. The primary intention is to analyse delaminated composite panels and estimate Strain Energy Release Rate (SERR) parameters at the delamination front to feed into acceptability criteria. Large deformation analysis is necessary to cater for excessive rotational deformations in the delaminated sublaminate. Modified Virtual Crack Closure Integral (MVCCI) is used to estimate all the three SERR components at the delamination front from the finite element output containing displacements, strains and stresses. The applied loading conditions are particularly critical and compressive loading on the panel could lead to buckling of the delaminated sublaminate and consequent growth of delamination. Numerical results are presented for circular delamination of various sizes and delamination at various interfaces (varying depth-wise location) between the base-and the sub-laminates. Numerical data are also presented on the effect of bi-axial loading and in particular on compressive loading in both directions. The results can be used to estimate delamination tolerance at various depths (or at various interfaces) in the laminate.
Analysis of composite laminates with intra- and interlaminar damage
Progress in Aerospace Sciences, 2005
Failure process of composite laminate under quasi-static or fatigue loading involves sequential accumulation of intraand interlaminar damage. Matrix cracking parallel to the fibres in the off-axis plies is the first intralaminar damage mode observed. These cracks are either arrested at the interface or cause interlaminar damage (delamination) due to high interlaminar stresses at the ply interface. This paper summarises recent theoretical modelling developed by the authors on stiffness property degradation and mechanical behaviour of general symmetric laminates with off-axis ply cracks and crack-induced delaminations. Closed-form analytical expressions are derived for Mode I, Mode II and the total strain energy release rates associated with these damage modes. Dependence of strain energy release rates on crack density, delamination area and ply orientation angle in balanced and unbalanced symmetric laminates is examined and discussed. Also, stiffness degradation due to various types of damage is predicted and analysed. r
The use of advanced carbon fibre-reinforced composites in aircraft primary structures has been steadily increasing over past two decades due to their high specific strength and stiffness, and their tailoring as per the need. The composite panels used in primary structures of aircraft are liable to be buckling during its service periods. It is observed that structures can withstand substantial amount of loads after they have buckled. Therefore, an approach to efficiently design the postbuckled composite structures is required to be developed. The designers of the next generation of aircraft are looking into the aspect of postbuckling composite structures to achieve substantial improvements in aircraft structural efficiency. In this work, the postbuckling response and growth of circular delamination in flat and curved composite plates are investigated for different delamination sizes and their locations through the laminate thickness. The prediction of delamination initiation and growth is carried out using the strain energy release rates obtained from the finite element analysis and comparing them to B-K's mixed-mode fracture criterion. The failure load is thus predicted. Predicted results for onset of delamination growth compared well with experimental results. Its variation with different delamination sizes and their locations across panel thickness was also investigated. It is observed that the failure loads are influenced by the delamination sizes depending on their locations across the laminate thickness. The different delamination sizes at H/3 laminate thickness did not have significant effects on the variations of compressive strengths of the delaminated composite panel. But, the compressive strengths of the panels having different delamination sizes at H/2 laminate thickness are more than that at H/3 and increase linearly with increase in delamination sizes.