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delamination
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Delamination Modeling In Composite Material Under The First Failure Mode
, M.Sc. Thesis Sharif University of Technology ; Hosseini Kordkheyli, Ali (Supervisor)
Abstract
In this research, delamination in compound laminated materials under the I mode loading is studied. In this way, a Double Cantilever Beam is investigated, which is the only experiment to study delamination in standard compound laminated materials. At first, a survey and comprehension of the failure of these materials is performed and the major mode of failure, which is named Delamination Mode is understood. Next, a survey on the possible methods of investigating the delamination phenomena is presented. In the next chapter, possible numerical methods are analysed, and the better performance of Cohesive Zone Model and Virtual Crack Closure Technique is studied. In this research, using the...
Ultrasonic-Assisted Drilling of Glass Fiber Reinforced Composites
, M.Sc. Thesis Sharif University of Technology ; Akbari, Javad (Supervisor)
Abstract
The fiber-reinforced composite materials possess advantage for structural purpose in various industries. Delamination is recognized as one of the major causes of damage during drilling of fiber reinforced composites, which not only reduces the structural integrity, but also has the potential for long-term performance deterioration. It is difficult to produce precise quality holes with high efficiency by conventional drilling method. Drilling is frequently applied in production cycle while the anisotropy and nonhomogeneity of composite materials affect the chip deformation and machining behavior during drilling. In this thesis, a new non-traditional drilling technology is presented for solve...
Development of a Layer-wise Model For Prediction of Interlaminar Crack Growth in Laminated Composites Plates Under Cyclic Loading
, M.Sc. Thesis Sharif University of Technology ; Hosseini Kordkheili, Ali (Supervisor)
Abstract
In the present work, the beginning and progressive growth of delamination in laminated composites plates has been studied. Interlaminar stresses at free edge of laminate may give rise to edge delamination and result in failure of laminate. So we need to determine the exact interlaminar stresses to predict the failure of laminated composites. A computer code based on layerwise theory that can obtain the exact interlaminar stresses been developed. Comparison between the present study and finite element software result showed the good agreement.A fracture mechanics approach is used to analysis delamination propagation between layers of composites laminate. In this approach damage propagation...
A Nonlinear Layerwise Shell Finite Element for Delamination Analysis of Laminated Composite Structures under Large Deformation
, Ph.D. Dissertation Sharif University of Technology ; Hosseini Kordkheili, Ali (Supervisor)
Abstract
This thesis aims to develop a numerically efficient nonlinear layer-wise shell element formulation for delamination analysis of laminated composite shell structures. The element, in a mesoscale scheme, is formulated based on a zig-zag theory and features three translational degrees of freedom for each node on the mid-surface of the shell in addition with two rotational degrees of freedom for each layer. In this way, the displacement field is formulated via adapting the Mindlin-Reissner theory in each layer and an ordered second-order algorithm for finite rotations. To verify the proposed formulation, many popular benchmark problems for geometric nonlinear analysis of shell problems are...
Investigating and Designing Different Parameters of Composite Patch for Damaged Pipe
, M.Sc. Thesis Sharif University of Technology ; Abedian, Ali (Supervisor)
Abstract
This paper presents, various parameters of the composite patch for repairing and reinforcement the damaged composite pipe have been investigated. There are various parameters of the composite patch such as Laminate orientation, length, width, material and thickness of the patch. by changing these parameters in each analysis and comparing the results, the optimal patch for the damaged pipe is determined
Analysis of Delamination in Fiber-reinforced Composite Laminates Using Multiscale Modeling
, M.Sc. Thesis Sharif University of Technology ; Hosseini Kordkheili, Ali (Supervisor)
Abstract
This study presents delamination in fiber-reinforced composite laminates by using multiscale modeling. The meso modeling is used to derive the relationship between microcrack density and damage parameters. Next the selected failure model is applied to analyze the macroscale modeling. The progress of failure terms and the reduction of fiber and matrix properties implemented into ABAQUS/Standard, which enables an individual to create a new material behavior through the user subroutine UMAT. In the following, the contours associated with each of the damage parameters are obtained in each of the damage mode. Then for a specific material, the relationship between microcrack density and damage...
Study of Tool Geometry on Ultrasonic Assisted Drilling of Composite Laminates
, M.Sc. Thesis Sharif University of Technology ; Akbari, Javad (Supervisor)
Abstract
Delamination is a major problem in drilling of fiber-reinforced composite materials. Thrust force is an important factor leading to propagation of delamination during drilling process. One of effective methods to reduce machining forces is application of ultrasonic vibrations. In this study ultrasonic assisted drilling is applied to reduce thrust force in drilling of GFRP laminates. In order to conduct experiments a setup is designed and fabricated to apply both vibrations and rotation to drill bits. Using Taguchi method, a set of experiments is conducted with feed rate, spindle speed, point angle and ultrasonic vibration amplitude as control factors. The results show that applying...
Delamination Effect on Frequecny Response of a Laminated Composite Plate Using Piezoelectric Patches
, M.Sc. Thesis Sharif University of Technology ; Hosseini Kordkheili, Ali (Supervisor)
Abstract
Composite structures are subjected to different kinds of loadings in different workspaces, and sometimes these load conditions can damage them. Delamination is a common damage in composites. In this research, the delamination effect on modal behavior of a laminated composite plate is studied. To investigate this effect, the frequency response method is used and piezoelectric patches are used as a sensor and an actuator for extracting the frequency response. The aim of this project is to investigte presence and severity of the delamination. To survey the frequency response method, an intact and some damaged plates with one sensor and actuator are modeled with abaqus software and frequency...
Vibration based damage detection in smart non-uniform thickness laminated composite beams
, Article TIC-STH'09: 2009 IEEE Toronto International Conference - Science and Technology for Humanity, 26 September 2009 through 27 September 2009, Toronto, ON ; 2009 , Pages 176-181 ; 9781424438785 (ISBN) ; Saeedi, E ; Zabihollah, A ; Ahmadi, R ; Sharif University of Technology
Abstract
Laminated composite beams with non-uniform thickness are being used as primary structural elements in a wide range of advanced engineering applications. Tapered composite structures, formed by terminating some of the plies, create geometry and material discontinuities that act as sources for delamination initiation and propagation. Any small damage or delamination in these structures can progress rapidly without any visible external signs. Due to this reason early detection of damage in these systems during their service life is receiving increasing attention. The presence of a crack in a component or structure leads to changes in its global dynamic characteristics results in decreases in...
Vibration analysis of delaminated Timoshenko beams under the motion of a constant amplitude point force traveling with uniform velocity
, Article International Journal of Mechanical Sciences ; Volume 70 , 2013 , Pages 39-49 ; 00207403 (ISSN) ; Jafari Talookolaei, R. A ; Ahmadian, M. T ; Sharif University of Technology
2013
Abstract
A composite beam with single delamination traveled by a constant amplitude moving force is modeled accounting for the Poisson's effect, shear deformation and rotary inertia. The mechanical behavior between the delaminated surfaces is modeled using a piecewise-linear spring foundation. The governing differential equations of motion for such system are derived. Primarily, eigen-solution technique is used to obtain the natural frequencies and their corresponding mode shapes of such beam. Then, the Ritz method is employed to derive the dynamic response of the beam due to the moving force. The obtained results for the free and forced vibrations of beams are verified against reported similar...
Toughness enhancement in roll-bonded Al6061-15 vol.% SiC laminates via controlled interfacial delamination
, Article Journal of Materials Engineering and Performance ; Volume 22, Issue 11 , 2013 , Pages 3414-3420 ; 10599495 (ISSN) ; Bagheri, R ; Reihani, S. M. S ; Sharif University of Technology
2013
Abstract
Researchers have examined different approaches to improve damage tolerance of discontinuously reinforced aluminum (DRA). In this study, three-layer DRA laminates containing two exterior layers of Al6061-15 vol.% SiCp and an interlayer of Al1050 were fabricated by hot roll bonding. Interfacial adhesion between the layers was controlled by means of rolling stain. The results of shear test revealed that, the bonding strength of laminates was influenced by number of rolling passes. Considering this effect, the role of interfacial bonding on the toughness of laminates was studied under three-point bending in the crack divider orientation. The quasi-static toughness of the laminates was greater...
The influence of fiber/matrix debonding on inelastic micro-mechanical behavior of cross-ply IMC composites
, Article ASME 2010 10th Biennial Conference on Engineering Systems Design and Analysis, ESDA2010, 12 July 2010 through 14 July 2010, Istanbul ; Volume 4 , 2010 , Pages 197-222 ; 9780791849187 (ISBN) ; Abedian, A ; Sharif University of Technology
2010
Abstract
In this study the effect of stress field on delamination and fiber/ matrix debonding in laminated composite panels is investigated from the micro-mechanical point of view by means of 3-D Finite Element Models. Specifically, the behavior of two-layer cross-ply symmetric laminates made up of SCS-6/Ti-24Al-11Nb Intermetallic Matrix Composite (IMC) during cooling from the processing temperature is studied. The results show that large plastic strains occur at the fiber/ matrix interface at the fiber end on the laminate free edge which may eventually extend to the interface of the layers of the laminate inflicting delamination damage. This phenomenon is more serious at the corner areas of the...
Separation of delamination modes in composite beams with symmetric delaminations
, Article Materials and Design ; Volume 27, Issue 10 , 2006 , Pages 900-910 ; 02613069 (ISSN) ; Nosier, A ; Farrahi, G. H ; Sharif University of Technology
Elsevier Ltd
2006
Abstract
Delaminated composite beam under general edge loading conditions is studied. Based on a technical engineering theory an analytical procedure for calculation of strain energy release rate and its separation into modes I and II of delamination is presented. By choosing a suitable displacement field based on second-order shear-thickness deformation theory and using the principle of minimum total potential energy, the equations of equilibrium are obtained along with the appropriate boundary conditions. The J integral and its definition for different modes of fracture is used for calculation of strain energy release rate and its separation into different modes. Double cantilever beam (DCB)...
Semi-analytical solution for the free vibration analysis of generally laminated composite Timoshenko beams with single delamination
, Article Composites Part B: Engineering ; Volume 45, Issue 1 , 2013 , Pages 587-600 ; 13598368 (ISSN) ; Ahmadian, M. T ; Jafari Talookolaei, R. A ; Abedi, M ; Sharif University of Technology
2013
Abstract
A rather new semi-analytical method towards investigating the free vibration analysis of generally laminated composite beam (LCB) with a delamination is presented. For the first time the combined effects of material couplings (bending-tension, bending-twist, and tension-twist couplings) with the effects of shear deformation, rotary inertia and Poisson's effect are taken into account. The semi-analytical solution for the natural frequencies and mode shapes are presented by incorporating the constraint conditions using the method of Lagrange multipliers. To verify the validity and the accuracy of the obtained results, they were compared with the results from other available references. Very...
Predicting delamination in multilayer composite circuit boards with bonded microelectronic components
, Article Engineering Fracture Mechanics ; 2017 ; 00137944 (ISSN) ; Nourani, A ; Spelt, J. K ; Sharif University of Technology
Elsevier Ltd
2017
Abstract
The present work developed a mixed-mode cohesive zone model (CZM) with a mode I failure criterion to predict the delamination bending loads of multilayer, composite printed circuit boards (PCBs) assembled with soldered ball grid array (BGA) components that were reinforced with an underfill epoxy adhesive. Two different delamination modes were observed in these microelectronic assemblies: delamination at the interface between the solder mask and the first conducting layer of the PCB, and PCB subsurface delamination at the interface between the epoxy and glass fibers of one of the prepreg layers. The cohesive parameters for each of the two crack paths were obtained from fracture tests of...
Predicting delamination in multilayer composite circuit boards with bonded microelectronic components
, Article Engineering Fracture Mechanics ; Volume 187 , 2018 , Pages 225-240 ; 00137944 (ISSN) ; Nourani, A ; Spelt, J. K ; Sharif University of Technology
Elsevier Ltd
2018
Abstract
The present work developed a mixed-mode cohesive zone model (CZM) with a mode I failure criterion to predict the delamination bending loads of multilayer, composite printed circuit boards (PCBs) assembled with soldered ball grid array (BGA) components that were reinforced with an underfill epoxy adhesive. Two different delamination modes were observed in these microelectronic assemblies: delamination at the interface between the solder mask and the first conducting layer of the PCB, and PCB subsurface delamination at the interface between the epoxy and glass fibers of one of the prepreg layers. The cohesive parameters for each of the two crack paths were obtained from fracture tests of...
Panel flutter analysis of general laminated composite plates
, Article Composite Structures ; Volume 92, Issue 12 , November , 2010 , Pages 2906-2915 ; 02638223 (ISSN) ; Rasekh, M ; Haddadpour, H ; Sharif University of Technology
2010
Abstract
The problem of nonlinear aeroelasticity of a general laminated composite plate in supersonic air flow is examined. The classical plate theory along with the von-Karman nonlinear strains is used for structural modeling, and linear piston theory is used for aerodynamic modeling. The coupled partial differential equations of motion are derived by use of Hamilton's principle and Galerkin's method is used to reduce the governing equations to a system of nonlinear ordinary differential equations in time, which are then solved by a direct numerical integration method. Effects of in-plane force, static pressure differential, fiber orientation and aerodynamic damping on the nonlinear aeroelastic...
On the dynamic response of a delaminated composite beam under the motion of an oscillating mass
, Article Journal of Composite Materials ; Volume 46, Issue 22 , 2012 , Pages 2863-2877 ; 00219983 (ISSN) ; Kargarnovin, M. H ; Ahmadian, M. T ; Sharif University of Technology
SAGE
2012
Abstract
The dynamic response of a delaminated composite beam under the motion of an oscillatory mass moving with a constant velocity has been studied. The delaminated composite beam is modeled as four interconnected sub-beams using the delamination limits as their boundaries. The constrained model is used to model the delamination region. The continuity and equilibrium conditions are forced to be satisfied between the adjoining beams. A set of derived governing differential equations along with those obtained by imposing boundary conditions are simultaneously solved in a closed form manner. The results for the response of the delaminated beam were compared with those of the intact beam. Furthermore,...
Molecular dynamics simulation of plastic deformation and interfacial delamination of NiTi/Ag bilayer by cyclic-nanoindentation: Effects of crystallographic orientation of substrate
, Article Computational Materials Science ; Volume 168 , 2019 , Pages 229-245 ; 09270256 (ISSN) ; Sadrnezhaad, S. k ; Sharif University of Technology
Elsevier B.V
2019
Abstract
This paper presents a comparative study of plasticity and fracture behavior of the NiTi/Ag bilayer for the different crystallographic orientations of the substrate. Molecular dynamic (MD) simulation was used to determine the deformation mechanism, dislocation density, plastic energy dissipation and delamination of the NiTi/Ag bilayers near the interface, when NiTi aligned at (1 0 0), (1 1 1), (1 1 0), (3 2 1), (2 1 0) and (2 1 1) faces during the cyclic-nanoindentation test. The Griffith energy balance model was used to estimate the energy release associated with the delamination. The results of the simulation are suggested the dependence of deformation mechanism, energy release rate (Gin),...
Modeling the R-curve effects in laminate composites using the interface thick level set method
, Article Theoretical and Applied Fracture Mechanics ; Volume 108 , August , 2020 ; Kouchakzadeh, M. A ; Sharif University of Technology
Elsevier B. V
2020
Abstract
This paper presents a new model for simulating delamination growth in composites in presence of the resistance curve (R-curve) effects. This model is extended from the interface thick level set (ITLS) method which is developed recently. In this approach the common definition of damage in the constitutive relationship of the interface elements is replaced with a new damage definition based on the thick level set (TLS) method. This new damage definition provides a direct link between fracture and damage mechanics that allows use of interface elements without a predefined cohesive law. In this paper the ITLS method is adopted to incorporate the R-curve effects caused by extended bridging, in...