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Dissertations / Theses on the topic 'Delamination'

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Published: 4 June 2021

Last updated: 7 September 2024

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1

Whitcomb, J. D. "Instability-related delamination growth of embedded and edge delaminations." Diss., Virginia Polytechnic Institute and State University, 1988. http://hdl.handle.net/10919/77755.

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Compressive loads can cause local buckling in composite laminates that have a near-surface delamination. This buckling causes load redistribution and secondary loads, which in turn cause interlaminer stresses and delamination growth. The goal of this research effort was to enhance the understanding of this instability-related delamination growth in laminates containing either an embedded or an edge delamination. There were three primary tasks: 1) development of a geometrically nonlinear finite element analysis named NONLIN3D; 2) performance of a parametric analytical study to determine the effects of strain, delamination shape, and delamination size on the distribution of the strain energy release rate components along the delamination front; and 3) performance of a combined experimental and analytical study of instability-related delamination growth (IRDG). Two material systems (AS4/PEEK and IM7/8551-7) and two stacking sequences (0/90/90/0)₆ and (90/0/0/90)₆ were examined. The laminates were fabricated with Kapton inserts between the fourth and fifth plies from the top surface to give an initial delamination. The analysis predicted a large variation of G_I and G_II along the delamination front. The G_III component was always small. The location of maximum G_I and G_II depended on the delamination shape and applied strain. In general, the strain-energy release rates were small except in a small region. Hence, delamination growth was expected to occur over only a small portion of the delamination front. Experiments corroborated this prediction. The laminate stacking sequence had a large effect on the shape of the deformed region, the direction of delamination growth, and the strain at which delamination growth occurred. These effects were predicted by the analysis. The G_I component appeared to govern initial delamination growth in the IM7/8551-7 laminates. Matrix ply cracking generally accompanied delamination growth. In some cases fiber micro-buckling also occurred shortly after delamination growth occurred.
Ph. D.

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2

Ding, Wei. "Delamination analysis of composite laminates." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0001/NQ41141.pdf.

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3

Wright, Jennifer Edith. "Compound bifurcations in delamination buckling." Thesis, University of Bath, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.432375.

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4

Batel, Mehdi. "Acoustic determination of adhesive bond delamination." Thesis, Georgia Institute of Technology, 2001. http://hdl.handle.net/1853/18201.

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5

Pernice, Maria Francesca. "On delamination migration in composite laminates." Thesis, University of Bristol, 2016. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.702469.

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Carbon fibre/epoxy composite laminates are well known to be susceptible to delamination. Delamination usually grows at interfaces between plies with dissimilar fibre orientation and may migrate from one interface to another, as in low-velocity impact damage or skin-stringer debonding. Much of the modelling work in the literature focuses on delamination contained within a single ply interface, using data from characterization tests in which delamination grows at interfaces between plies of the same fibre orientation, mainly because of a lack of understanding of the fundamental causes of delamination migration. However, to obtain representative results, delamination migration should be accounted for by finite element methods aimed at accurately simulating delamination growth. The objective of this work was to investigate and understand delamination migration at interfaces between plies with dissimilar fibre orientation in composite laminates. Initially, delamination migration was observed experimentally in a Double Cantilever Beam (DCB) specimen containing ±θ ply interfaces. Finite element analyses of the DCB specimen were then performed, to simulate delamination migration using a cohesive zone model-based approach. Comparison of experimental and numerical results highlighted the need for a more detailed experimental understanding of the fundamental driving forces for delamination migration, before methods to simulate delamination migration could be developed and validated. To this end, further experimental tests were conducted, using the Delamination Migration test method, recently developed at NASA Langley Research Center, which allows the isolation of a single migration event that can then be studied in detail. A novel delamination migration specimen was employed, to investigate delamination migration at a generic 0/θ° interface. Tests were performed in the laboratories of the Durability, Damage Tolerance and Reliability Branch at NASA Langley Research Center. Damage was characterised in detail using C-scan and X-ray Computed Tomography techniques. During the test, delamination initially propagated along a 0°/θ ply interface, by growing closer to one of the bounding plies, turning into it and subsequently arresting. Eventually, delamination migrated to a different 0/θ° ply interface. Linear elastic finite element analyses and the Virtual Crack Closure Technique were employed to interpret experimental results. Results suggested that delamination migration is governed by the shear stress sign and the strain energy release rate along the delamination front, which both vary across the specimen width at a 0/θ° ply interface. Results of this study represent a step forward in the understanding of the key mechanism of delamination propagation and migration at ply interfaces with dissimilar fibre orientation, and help in the understanding of complex damage patterns such as low-velocity impact. Understanding delamination migration can inform design of damage tolerant composite structures and provide guidelines and benchmark data to develop and validate modelling methods aimed at simulating and predicting delamination migration.

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6

Chong, Iok Tong. "Steam driven delamination in electronics packages /." View Abstract or Full-Text, 2002. http://library.ust.hk/cgi/db/thesis.pl?MECH%202002%20CHONG.

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7

Dinc, Dincer. "Delamination Of Layered Materials Under Impact Loading." Master's thesis, METU, 2003. http://etd.lib.metu.edu.tr/upload/1060623/index.pdf.

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In this study, a cold worked tool steel and a low carbon steel ( St 37 ), which were joined by brazing, were subjected to impact and shear loading. The end product is used as paper cutting blades in the industry. Effects of different brazing filler metals on the delamination of the blades under impact loading and on the impact toughness of the blades were studied. The target is to achieve higher impact toughness values without delamination. Impact toughness of the steels, joined by Cu, CuNi and BNi brazing filler metals and separation of brazed surfaces under shear loading were studied. The microstructures that were formed as a result of each application were studied by scanning electron microscopy and x-ray diffraction. The results indicate that brittle intermetallic compounds are formed in BNi brazing filler metal application. It is observed that CuNi alloy with 24% wt Ni form stronger bonds with the base metals than pure Cu and 10% wt Ni CuNi alloy.

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8

Olsson, Robin. "Impact response and delamination of composite plates /." Stockholm, 1998. http://www.lib.kth.se/abs98/olss0528.pdf.

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9

Dávila, Carlos G. "Delamination initiation in postbuckled dropped-ply laminates /." This resource online, 1991. http://scholar.lib.vt.edu/theses/available/etd-07282008-134842/.

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10

Brewer, John C. (John Charles) 1961. "Failure of graphite/epoxy induced by delamination." Thesis, Massachusetts Institute of Technology, 1988. http://hdl.handle.net/1721.1/35945.

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11

Alessa, Hassan Ali. "Delamination in Hybrid Carbon/Glass Fiber Composites." University of Dayton / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1399037290.

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12

Blandon, Omar Ali. "Mechanism of Delamination of Electrospun Adhesive Nanofibers." University of Akron / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=akron1446477512.

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13

Dávila, Carlos G. "Delamination initiation in postbuckled dropped-ply laminates." Diss., Virginia Tech, 1991. http://hdl.handle.net/10919/38915.

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14

Maor, Yonah. "Delamination of oil paints from acrylic grounds." Thesis, Kingston, Ont. : [s.n.], 2008. http://hdl.handle.net/1974/1487.

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15

Wang, Bin. "Local delamination failure of thin material layers." Thesis, Loughborough University, 2017. https://dspace.lboro.ac.uk/2134/25128.

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Thin material layers have found various applications with various roles of functions, such as in fibre reinforced laminated composite materials, in integrated electronic circuits, in thermal barrier coating material system, and etc. Interface delamination is a major failure mode due to either residual stress or applied load, or both. Over the past several decades, extensive research works have been done on this subject; however, there are still uncertainties and unsolved problems. This thesis presents the new developed analytical studies on local delamination failure of thin material layers. Firstly, the analytical theories are developed for post-local buckling-driven delamination in bilayer composite beams. The total energy release rate (ERR) is obtained more accurately by including the axial strain energy contribution from the intact part of the beam and by developing a more accurate expression for the post-buckling mode shape. The total ERR is partitioned by using partition theories based on the Euler beam, Timoshenko beam and 2D-elasticity theories. By comparing with independent test results, it has been found that for macroscopic thin material layers the analytical partitions based on the Euler beam theory predicts the propagation behaviour very well and much better than the others. Secondly, a hypothesis is made that delamination can be driven by pockets of energy concentration (PECs) in the form of pockets of tensile stress and shear stress on and around the interface between a microscopic thin film and a thick substrate. Both straight-edged and circular-edged spallation are considered. The three mechanical models are established using mixed-mode partition theories based on classical plate theory, first-order shear-deformable plate theory and full 2D elasticity theory. Experimental results show that all three of the models predict the initiation of unstable growth and the size of spallation very well; however, only the 2D elasticity-based model predicts final kinking off well. Based on PECs theory, the room temperature spallation of α-alumina oxidation film is explained very well. This solved the problem which can not be explained by conventional buckling theory. Finally, the analytical models are also developed to predict the adhesion energy between multilayer graphene membranes and thick substrates. Experimental results show that the model based on 2D elasticity partition theory gives excellent predictions. It has been found that the sliding effect in multilayered graphene membranes leads to a decrease in adhesion toughness measurements when using the circular blister test.

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16

Yilmaz, Suphi. "Buckling Driven Delamination Of Orthotropic Functionally Graded Materials." Master's thesis, METU, 2006. http://etd.lib.metu.edu.tr/upload/3/12607836/index.pdf.

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In today'
s technology severe working conditions increase demands on structural materials. A class of materials which are developed to meet these increased demands is Functionally Graded Materials (FGMs). These are inhomogeneous structural materials which are able to withstand large temperature gradients and corrosive environment. Application areas of FGMs are in aerospace industry, nuclear reactors, chemical plants and turbine systems. FGMs have gradual compositional variation from metal to ceramic which give them mechanical strength, toughness and heat resistance. However under high temperature gradients, cracking problems may arise due to thermal stresses. In layered structures the final stage of failure may be delamination due to crack extension. The objective of this study is to model a particular type of crack problem in a layered structure consisting of a substrate, a bond coat and an orthotropic FGM coating. There is an internal crack in the orthotropic layer and it is perpendicular to material gradation of coating. The position of the crack inside the coating is kept as a variable. The steady-state temperature distribution between the substrate and the coating causes a buckled shape along crack face. The critical temperature change, temperature distribution, mixed mode stress intensity values and energy release rates are calculated by using Displacement Correlation Technique. Results of this study present the effects of geometric parameters such as crack length, crack position, etc as well as the effects of the type of gradation on buckling behavior and mixed mode stress intensity factors.

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17

Makama, Zakari. "Cathodic delamination of modelled sea cable connector assemblies." Thesis, University of Portsmouth, 2011. https://researchportal.port.ac.uk/portal/en/theses/cathodic-delamination-of-modelled-sea-cable-connector-assemblies(a33106ba-ff68-4ed9-bd86-ef1fb9172125).html.

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Cathodic delamination failure is believed to be caused by the production of OH- at the polymer/metal interface via oxygen reduction reactions. In cable connector assemblies, the use of manufacturing processes and materials that are resistant to cathodic delamination failures is highly desirable. Also, there is a need for an accelerated testing regime for assessing the resistance of polymer-to-metal composites to cathodic delamination failures. Cable connector assemblies are employed in marine environments for structural terminations and circuit interconnection of electrical power and signal cabling systems. They are found on offshore sea beds, ROV’s, vessels and submarines and are prone to cathodic delamination related failures particularly when the cable assemblies are coupled to dissimilar metal appurtenances in seawater, e.g., zinc anodes. The resistance to cathodic delamination failures of selected metal substrates and polymeric materials used in the manufacture and sealing of cable connector assemblies have been investigated. Materials and methods of surface preparation by grit blasting to enhance polymer-to-metal adhesion, thus increasing the service life-time expectation of cable connector assemblies have been elucidated. Methods of accelerated testing of polymer/metal bond durability using salt spray test and the validation of the results in seawater immersion tests and potentiostatic experiments have been described. Also, a novel accelerated test chamber for cathodic delamination tests was designed and manufactured. Applied potential was observed to be the factor that had the most negative effect on test samples while silicon carbide grit was found to produce the most effective surface cleanliness and roughness combination required for durable polymer-to-metal bonds.

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18

Van, Hoof J. "Modelling of impact induced delamination in composite materials." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape4/PQDD_0028/NQ52335.pdf.

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19

Huang, Haiying. "Single and multiple delamination behavior in composite plates." Diss., Georgia Institute of Technology, 1998. http://hdl.handle.net/1853/12541.

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20

Tian, Hong. "Tribology and interfacial delamination of thin film systems." Thesis, Massachusetts Institute of Technology, 1990. http://hdl.handle.net/1721.1/13675.

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21

Xia, Qingxi 1973. "Mechanics of inelastic deformation and delamination in paperboard." Thesis, Massachusetts Institute of Technology, 2002. http://hdl.handle.net/1721.1/8334.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2002.
Includes bibliographical references (p. 233-236).
Paperboard is one of the most widely used materials. The inelastic deformation of paperboard plays a crucial role during many manufacturing processes (e.g., the converting process whereby paperboard is converted into a product such as a milk carton by punching and subsequent folding) and during in-service applications. There is a scarcity of constitutive models describing inelastic behavior of paperboard under complex loading, despite the paper industry's great need of analytical tools to aid the design and manufacturing of better paperboard products. In this thesis, two constitutive models are developed to model the highly anisotropic, elastic-plastic behavior of paperboard/paper: (1) A three-dimensional elastic-plastic interface constitutive model is developed to model the out-of-plane delamination behavior of paperboard. The onset of interface separation is controlled by a limit surface in the normal-shear traction space. The limit surface is taken to shrink with a monotonically-increasing scalar internal variable reflecting damage associated with the history of inelastic relative interface displacement. (2) A three-dimensional, anisotropic continuum constitutive model is developed to model the in-plane elastic-plastic deformation of paper and paperboard. The proposed initial yield surface is directly constructed from the yield strengths measured in various loading directions and the corresponding ratios of plastic strain components. An associated flow rule is used to model the plastic flow of the material. Anisotropic strain-hardening of yield strengths is introduced to model the evolution of the yield surface with inelastic strain.
(cont.) The two constitutive models are implemented into finite element software to enable the simulation of paperboard mechanical behavior under complex, finite deformation. The models are shown to be capable of accurately capturing both the out-of-plane delamination (via the interface model) and the anisotropic in-plane elastic-plastic (via the continuum in-plane model) behavior of paperboard under complex loading. The two models are combined to simulate the mechanics of a converting process (creasing and subsequent folding) of paperboard. The simulations agree well with corresponding experimental observations. In particular, the underlying mechanisms of damage and delamination development during creasing and subsequent folding are predicted well; the macroscopic response of the bending moment vs. bending angle also agrees with experimental data. This research provides physically based three-dimensional material models of the anisotropic, elastic-plastic deformation of paperboard that enable the computational design of paperboard process and product design.
by Qingxi Steve Xia.
Ph.D.

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22

Marinari, E. "A study of epithelial cell delamination in Drosophila." Thesis, University College London (University of London), 2011. http://discovery.ucl.ac.uk/1334504/.

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The developmental refinement of an epithelium requires finely balanced rates of growth and cell loss. However, the molecular mechanisms that regulate the achievement of homeostasis, which are likely to be deregulated in tumorigenesis, remain poorly understood. In this work using the fly notum as a model system and laser cutting experiments to test in vivo tissue mechanics, I describe a novel process of live cell delamination that counter-balances tissue growth to ensure the achievement of mechanical equilibrium in the final phases of development. The fly notum is an ideal system to study this type of mechanical buffering since it remains approximately constant in size during the final phases of tissue refinement in development, whilst requiring cell growth, division and cell loss. Individual cells leaving overcrowded regions of the notum by live cell delamination follow a path of progressive junctional and apical area loss, in a 2-step mechanism that is independent of cell death. Cells first undergo serial junctional loss, leading to a cell with a small apex and few sides, followed by Myosin-II driven apical extrusion. This process of live cell delamination can be recapitulated by a simple vertex model of epithelial mechanics, where pressure is relieved as cells leave the tissue via a series of stochastic neighbor exchange events. These findings suggest that crowding-induced live cell delamination is a generic mechanism that buffers epithelia against variations in growth. This has important implications for our understanding of homeostasis and its deregulation in cancer, as well as for cancer cell invasion and metastasis.

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23

Canturri, Gispert Carla. "On delamination directionality and migration in laminated composites." Thesis, Imperial College London, 2014. http://hdl.handle.net/10044/1/18169.

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Delamination is recognised as the most critical damage process in laminated composites under compressive or bending loading conditions and managing this failure mode has been key to using composites in primary structures. However, predictive modelling of delamination growth has been limited, since even a simple, single plane defect can result in multiplane delamination growth which is often associated to other secondary processes such as intralaminar or translaminar damage. The objective of this thesis has been to experimentally investigate the fundamental phenomena associated with delamination growth which were isolated from the observations made in embedded defects: delamination preferentially grows along the direction of the fibres at a ply interface (directionality) and, if forced to grow obliquely to the fibres, a change of delamination plane typically ensues (migration). Directionality was demonstrated with a bespoke test to grow delamination in a preferential direction. The geometrical effect of the fibres on the direction of delamination growth was also studied using a macroscopic model of the delaminating interface. A numerical strategy was introduced to model directionality. Cohesive elements and the virtual crack closure technique were modified to include the effect of fibre orientation at the interface at which delamination propagated. Migration was isolated with a series of delamination tests in cross-ply laminates under variable mode mixities. Finally, the insight gained in delamination growth mechanisms was demonstrated on a set of sandwich configurations with embedded defects to understand growth in complex composite geometries. Fractographic studies were used to glean a detailed understanding of the migration process. This work has successfully characterised the detailed processes by which delaminations grow and provided knowledge to develop damage tolerant designs.

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24

Johansson-Näslund, Markus. "Numerical analysis of paperboard delamination using cohesive elements." Thesis, KTH, Hållfasthetslära, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-277779.

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A new test method for measuring the shear strength associated with mode III delamination of paperboard is studied with the purpose of reducing the size of the test configuration. The method, which uses a split cantilever beam (SCB) specimen, measures the shear strength indirectly through the fracture resistance. The methodology is based on the double cantilever beam (DCB) specimen, used for measuring the normal delamination strength of paperboard. The study is based on finite element analyses, where cohesive elements are implemented for predicting the fracture response. An experimental evaluation of the test method was carried out in a pre-study conducted between Karlstad, Skövde and Lund University together with Tetra Pak. The experiments considered both the SCB-specimen and the standardised DCB-specimen, and for determination of the fracture behaviour the cohesive law presented by Tryding & Ristinmaa (2017) were considered. The result obtained from the experiments is used as a basis for evaluating the analyses. To model the fracture development, the relation presented by Tryding & Ristinmaa (2017) is implemented in the commercial finite element software Abaqus through a user-specified element. From the analyses of the DCB-specimen it is shown that through implementation of a specified cohesive law, it is possible to simulate mode I fracture development of paperboard in an accurate manner. The results for the DCB analyses correlate well with the experimental results. The result for the SCBspecimen shows a deviating behaviour from the experimental result by underestimating the shear strength. It is noted that the specimen is subjected to notable deformations in both the first shear direction and the normal direction, preventing pure shear loading from being obtained. Based on the analyses, it is indicated that the current test configuration does not obtain pure shear separation in mode III, and thereby underestimates the actual shear strength of the paperboard. It is also shown that reducing the specimen length with 400 mm has no significant impact on the properties related to the cohesive law. By altering the initial crack length, it is possible to further reduce the length of the specimen. However, to prevent development of unstable fracture, the length of the paperboard should exceed 300 mm. Alternating the crack length and the width of the paperboard also seems to contribute to lower displacements in the normal direction and provides a better fit with the experiments. Tryding, J. & Ristinmaa, M. (2017). Normalization of cohesive laws for quasi-brittle materials. Engineering Fracture Mechanics, 178, 333-345. doi:10.1016/j.engfracmech.2017.03.020
En ny testmetod för att mäta skjuvstyrkan för modus III delaminering av kartong studeras i syftet att reducera testutrustningens storlek. Testmetoden, som använder sig av en delad konsolbalk (SCB), mäter skjuvstyrkan indirekt genom brottresistansen. Metodiken är baserad på det standardiserad konsolbalks testet DCB, var två balkar är sammankopplade och som används för att mäta delaminering styrkan i kartongens normala riktning. Studien baseras på analyser med finita element, var kohesiva element implementeras för att prediktera brottbeteendet. En experimentell utvärdering av testmetoden genomfördes i en förstudie mellan Karlstads, Skövdes och Lunds universitet tillsammans med Tetra Pak. Experimenten gjordes både för DCB- och SCB-testet, och för att utvärdera brottbeteendet användes de kohesiva lagarna som presenterats av Tryding & Ristinmaa (2017). De experimentella resultaten används som bas vid utvärdering av analyserna. För att modellera spricktillväxten implementeras de kohesiva lagarna i det kommersiella FEM programmet Abaqus genom ett användar specificerat element (UEL). Från analyserna av DCB-testet visas det att det är möjligt att simulera modus I sprickbildning i kartong genom implementering av en specifik kohesive lag. Simuleringarna av DCB-testet stämmer väl överens med de experimentella resultaten. Resultaten från SCB-analyserna visar däremot på ett avvikande beteende från experimenten genom att underskatta skjuvstyrkan. Det noteras i analyserna av SCB-testet att märkbara deformationer i både den första skjuvriktningen och normal riktningen uppkommer, vilket förhindrar att ren skjuvbelastning i modus III erhålls. Baserat på analysernas resultat indikeras det att den nuvarande konfiguration för SCB-testet inte ger ren skjuvbelastning i modus III och underskattar därför kartongens faktiska skjuvstyrka. Det visas också att en 400 mm reducering av SCB-geometrins längd inte har någon märkbar påverkan på de kohesiva egenskaperna. Genom att ändra den initiala spricklängden är det möjligt att ytterligare reducera SCBgeometrins längd. För att försäkra sig om att sprickas tillväxt förblir stabil bör däremot längden på kartongen överstiga 300 mm. Att minska den initiala spricklängden och bredden på kartongen verkar generellt bidra till lägre deformationer i normal riktningen och ett resultat som ligger närmare de experimentella. Tryding, J. & Ristinmaa, M. (2017). Normalization of cohesive laws for quasi-brittle materials. Engineering Fracture Mechanics, 178, 333-345. doi:10.1016/j.engfracmech.2017.03.020

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25

Van, Hoof Jack (Jacobus Franciscus Adrianus Maria) Carleton University Dissertation Engineering Mechanical and Aerospace. "Modelling of impact induced delamination in composite materials." Ottawa, 1999.

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26

Dardano, Nicola. "Delamination of thin layers promoted by local buckling." Thesis, IMT Alti Studi Lucca, 2022. http://e-theses.imtlucca.it/363/1/Dardano_phdthesis.pdf.

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This dissertation investigates the combined phenomena of buckling and fracture, which occur in thin superficial layers subjected to compressive forces. As a representative case, the four-point bending test on laminated specimens with midspan, through-the-width delaminations, is taken into consideration: a mechanical model of the test was developed and experimental tests on carbon fiber laminates were conducted. The thesis is subdivided into six Chapters. Chapter 1 presents a general introduction to the investigated problem. Chapter 2 illustrates the state of the art on delamination in composite materials with focus on buckling-driven delamination and four-point bending tests. Chapter 3 illustrates the experimental Mode II fracture toughness characterization of the carbon fiber laminates investigated in the thesis. In Chapter 4, the experimental campaign with four-point bending tests is illustrated. Chapter 5 presents the analytical model to simulate and interpret the four-point bending tests. Chapter 6 shows a comparison between the analytical prediction and the experimental evidence. In Chapter 7, results are summarized and future developments are outlined.

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27

DARBAN, HOSSEIN. "Multiscale modeling of delamination fracture in multilayered structures." Doctoral thesis, Università degli studi di Genova, 2018. http://hdl.handle.net/11567/930607.

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In the recent years, there has been increased interest in using multilayered structures in the construction of mechanical devices and vehicles, such as turbines, wind-blades, aircrafts or ships. These structures are often subjected to severe mechanical loads and a wide range of operational temperatures. Under such loading conditions, the stresses in multilayered structures may exceed the elastic limit, and delaminations and debonds may form and propagate as a consequence of the high interfacial tractions caused by the inhomogeneous material structure. To design layered systems and define their load-bearing capacity and life, accurate understanding of their mechanical behavior in the elastic and post-elastic regimes is needed.

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28

Allahar, Kerry N. "Mathematical modeling of disbonded coating and cathodic delamination systems." [Gainesville, Fla.] : University of Florida, 2003. http://purl.fcla.edu/fcla/etd/UFE0001246.

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29

Jinnestrand, Magnus. "Delamination in APS applied thermal barrier coatings : life modelling /." Linköping : Univ, 2004. http://www.bibl.liu.se/liupubl/disp/disp2004/tek902s.pdf.

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30

Malik, Basharat U. "Fatigue delamination growth under cyclic compression in unidirectional composites." Diss., Georgia Institute of Technology, 1995. http://hdl.handle.net/1853/12094.

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31

Harries, Richard. "Process modeling and interfacial delamination in peripheral array packages." Thesis, Georgia Institute of Technology, 1998. http://hdl.handle.net/1853/16622.

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32

Hearing, Brian Phillip 1972. "Delamination in reinforced concrete retrofitted with fiber reinforced plastics." Thesis, Massachusetts Institute of Technology, 2000. http://hdl.handle.net/1721.1/9141.

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Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2000.
Includes bibliographical references (leaves 251-269).
The addition of fiber-reinforced plastic (FRP) laminates bonded to the tension face of concrete members is becoming an attractive solution to the rehabilitation and retrofit of damaged structural systems. Flexural strength is enhanced with this method but the failure behavior of the system can become more brittle, often involving delamination of the composite. This study investigates failure modes including delamination with the use of fiber reinforced plastics to rehabilitate various concrete structures. The focus is on delamination and its causes, specifically in the presence of existing cracks in the retrofitted concrete system. First, delamination processes in FRP retrofitted concrete systems are studied through combined experimental and analytical procedures. The delamination process is observed to initiate in the concrete substrate with micro cracks that coalesce into an unstable macro crack at failure. This macroscopic behavior is modeled through a finite element procedure with a smeared crack approach, which is found to be limited in the ability to represent the stress intensity at the delamination tip. For this reason it is shown that interfacial fracture mechanics can be used to describe the bimaterial elasticity and complex stress intensity at the delamination tip and provide a criterion governing the propagation of delamination using energy methods. Then, peeling processes occurring at existing cracks in the retrofitted system are studied through fracture mechanics based experimental and analytical procedures. An experimental program involving specialized shear notch specimens demonstrates that the location of the notch and laminate development length are influential on the shear crack peeling process. A finite element procedure is used to evaluate the crack driving forces applied at the shear notch crack mouth, and the fracture analysis is extended to evaluate initiation of peeling at the shear notch scenario. Finally, delamination failures in FRP retrofitted reinforced concrete beams representing "real-life" retrofit scenarios are investigated. An experimental and analytical program is conducted to investigate influences on the failure processes. The application of the fracture based peeling analysis to a quantitative design procedure is investigated, and a computational design aid to assist the iterative design procedure is developed.
by Brian Phillip Hearing.
Ph.D.

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Gregory, Jeremy R. (Jeremy Ryan) 1976. "Relating polymer matrix composite delamination behavior to constituent properties." Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/18061.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2004.
Includes bibliographical references (p. 183-194).
Developing predictive capabilities of composite material behavior from constituent properties is an important component of accelerating materials insertion. Many models exist that accomplish this objective for a range of material properties, but no such method is available for delamination properties. This thesis explores the issues associated with predicting polymer matrix composite Mode I delamination behavior from constituent properties by examining the topic from a variety of perspectives. Nanoindentation tests of matrix materials in composites and their associated neat polymers analyze the assumption that neat matrix properties are the same as unconstrained in situ properties and therefore may be used in models predicting composite behavior from constituent properties. Quasi-static and fatigue fracture experiments using a graphite/epoxy composite and its neat resin at a variety of temperatures and loading rates allow for an examination of the dominant mechanisms involved in the fracture process, an analysis of the shifts in quasi-static behavior with temperature and potential implications for fatigue predictions, and measurement of values that will act as inputs and verification of a delamination initiation model. A global-local finite element model of a double cantilever beam specimen is used to study the prediction of delamination initiation by examining inelastic matrix deformation at the crack tip. In addition, a fiber bridging fatigue model is created to analyze crack propagation data that effectively separates the bridging and resin crack tip contributions. The final component of the thesis is to tie the various experimental and analytical studies together to create methodologies that may be used in a design or research environment
(cont.) to accelerate materials insertion. An important conclusion from the thesis is that quantitative predictions of composite fracture behavior using unmodified neat matrix properties is not feasible, but the constrained matrix properties may be used to predict composite delamination behavior. It is also shown that following a process of implementing mechanism-based models in conjunction with experimental observations is essential when implementing models that bridge lengthscales.
by Jeremy Ryan Gregory.
Ph.D.

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Petrossian, Zackarias. "Delamination in composite laminates with curvature and discontinuous plies." Thesis, University of Bristol, 1998. http://hdl.handle.net/1983/8965c2a2-d0bf-4c6b-8788-6840e4e7f559.

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Tai, Roger Cheong-Ling. "Delamination of adhesive bonded automotive joints in corrosive environments /." The Ohio State University, 1992. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487779439845532.

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Barlas, Fatma Aylin. "Variable complexity modeling of postbuckled stiffeners for delamination initiation." Thesis, This resource online, 1993. http://scholar.lib.vt.edu/theses/available/etd-10312009-020245/.

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Xu, Ying. "Detection of delamination in composites with fiber optic sensor /." View abstract or full-text, 2004. http://library.ust.hk/cgi/db/thesis.pl?CIVL%202004%20XU.

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Thesis (Ph. D.)--Hong Kong University of Science and Technology, 2004.
Includes bibliographical references (leaves 194-209). Also available in electronic version. Access restricted to campus users.

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Daniewicz, David Joseph 1965. "Edge delamination in advanced laminated composites, theory and verification." Thesis, The University of Arizona, 1990. http://hdl.handle.net/10150/277294.

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A damage evolution theory capable of predicting the effects of edge delamination phenomena on composite laminate response is developed. The theory is a mechanics-based formulation which quantifies the damage development of a laminate under general loading, and incorporates it directly to the constitutive behavior of the laminate. The theoretical development introduces a laminate-specific constant φ; the methodology of φ selection is presented for [±15/±50]s, [±45/0/90]s, and [0₂/90₂]s T300 graphite/epoxy laminates. Edge effects are demonstrated by comparing the damage state of the above laminates with and without edge delamination damage. The capability of the theory in predicting the volume scaling effect is shown through consideration of the failure strengths of the [±25/90n]s laminate series.

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Patil, Anjali Narendra. "Delamination Detection in Concrete Using Disposable Impactors for Excitation." BYU ScholarsArchive, 2013. https://scholarsarchive.byu.edu/etd/3885.

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Delaminations in concrete bridge decks result primarily from corrosion of the reinforcing bars (or rebar). This corrosion leads to volumetric expansion of the rebar. When the rebar expands, concrete cracks, and there is a localized separation of the concrete cover from the underlying concrete. Impact-echo testing is an effective technique to map delaminations on concrete bridge decks. However, mapping speed is limited by necessary retrieval of the impactor for traditional tests. To achieve higher scanning speeds, it is advantageous to use both a non-contact measurement (air-coupled impact-echo) and disposable-impactor excitation. Disposable impactors have the potential advantage of achieving greater deck scanning speeds because they do not need to be retrieved, and they can also be used with air-coupled measurement systems. This thesis reports impact excitation of concrete using disposable impactors such as water droplets and ice balls. The impact characteristics of these impactors are compared with those of steel balls and chain links. Comparing the acoustic recordings on intact and delaminated concrete surface shows that water droplets and ice balls are able to excite flexural resonant modes associated with delamination defects. The use of water droplets and ice balls for shallow delamination detection in concrete is thus demonstrated.

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Moser, Achim. "Experimentelle Untersuchungen zum Ablöseverhalten in einem Polymer-Glasfüllstoff-System." [S.l. : s.n.], 2001. http://www.bsz-bw.de/cgi-bin/xvms.cgi?SWB10047782.

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Liu, Juanyu. "Early age delamination in concrete pavements made with gravel aggregates." Thesis, [College Station, Tex. : Texas A&M University, 2006. http://hdl.handle.net/1969.1/ETD-TAMU-1767.

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Waters, Patrick. "The effects of moisture on thin film delamination and adhesion." [Tampa, Fla.] : University of South Florida, 2005. http://purl.fcla.edu/fcla/etd/SFE0001164.

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Gozluklu, Burak. "Delamination Analysis By Using Cohesive Interface Elements In Laminated Composites." Master's thesis, METU, 2009. http://etd.lib.metu.edu.tr/upload/12611005/index.pdf.

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Finite element analysis using Cohesive Zone Method (CZM) is a commonly used method to investigate delamination in laminated composites. In this study, two plane strain, zero-thickness six-node quadratic (6-NQ) and four-node linear (4-NL) interface elements are developed to implement CZM. Two main approaches for CZM formulation are categorized as Unified Mode Approach (UMA) and Separated Mode Approach (SMA), and implemented into 6-NQ interface elements to model a double cantilever beam (DCB) test of a unidirectional laminated composite. The results of the approaches are nearly identical. However, it is theoretically shown that SMA spawns non-symmetric tangent stiffness matrices, which may lower convergence and/or overall performance, for mixed-mode loading cases. Next, a UMA constitutive relationship is rederived. The artificial modifications for improving convergence rates such as lowering penalty stiffness, weakening interfacial strength and using 6-NQ instead of 4-NL interface elements are investigated by using the derived UMA and the DCB test model. The modifications in interfacial strength and penalty stiffness indicate that the convergence may be improved by lowering either parameter. However, over-softening is found to occur if lowering is performed excessively. The morphological differences between the meshes of the models using 6-NQ and 4-NL interface elements are shown. As a consequence, it is highlighted that the impact to convergence performance and overall performance might be in opposite. Additionally, benefits of selecting CZM over other methods are discussed, in particular by theoretical comparisons with the popular Virtual Crack Closure Technique. Finally, the numerical solution scheme and the Arc-Length Method are discussed.

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Datta, Sidhyartha. "Investigation of the micromechanics of delamination in fibre reinforced composites." Thesis, Imperial College London, 2005. http://hdl.handle.net/10044/1/7867.

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Greenhalgh, Emile Smith. "Characterisation of mixed-mode delamination growth in carbon-fibre composites." Thesis, Imperial College London, 1998. http://hdl.handle.net/10044/1/7975.

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Borg, Rikard. "Simulation of delamination initiation and growth in fiber composite laminates /." Linköping : Division of Solid Mechanics, Dept. of Mechanical Engineering [Hållfasthetslära, Institutionen för konstruktions- och produktionsteknik], Univ, 2002. http://www.bibl.liu.se/liupubl/disp/disp2002/tek776s.pdf.

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Tenek, Lazarus H. "Delamination dynamics and vibrothermographic-thermoelastic evaluation of advanced composite materials." Thesis, This resource online, 1991. http://scholar.lib.vt.edu/theses/available/etd-10312009-020116/.

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Gao, Jie, Zhibo Pang, Qiang Chen, and Li-Rong Zheng. "Interactive Packaging Solutions Based on RFIDTechnology and Controlled Delamination Material." KTH, Elektroniksystem, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-50193.

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Interactive packaging is an emerging research area in recent years. It brings people convenient and smart lives, reduces consumption of traditional packaging materials and direct or indirect labor costs as well. Being integrated in interactive packaging, Radio Frequency Identification (RFID) technology becomes one of the most proactive development enablers. In this paper, an interactive and intelligent packaging solution integrating passive RFID system and Controlled Delamination Material (CDM) is given at first. Package opening action is electrically controlled by the RFID system. CDM is primarily used in aerospace applications in the past and the conductor/adhesive joint can be easily opened by applying a little electric power on to the material. Some related works will be shown about the electrochemical characteristics of CDM in order to facilitate the system design. A demonstration system was developed and the test results have proved feasibility of the solution and shown the potential of low cost for mass production. Based on this solution, an interactive medication package for pervasive healthcare is further developed, using EPCglobal Gen2 RFID technology. It will make the medication being accessible for patient only at the prescribed dose and time, and medication taking information will be delivered as well. Such medication package will not only give unprecedented high patient compliance, but also improve the communication between patients and healthcare staffs.
QC 20111202

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Palmer, David W. "The effect of internal delamination on unsymmetric laminated composite plates." Diss., Georgia Institute of Technology, 1995. http://hdl.handle.net/1853/12021.

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Chen, Zi Qi. "Delamination buckling of pressure-loaded laminated cylindrical shells and panels." Diss., Georgia Institute of Technology, 1987. http://hdl.handle.net/1853/21227.

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