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Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 25 for “"cohesive failure"”.
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Multi-Scale Cohesive Failure Modeling of Heterogeneous Adhesives
… part of this work, we examine the microscopic failure processes and their effect on the macroscopic failure response of stiff-inclusion-reinforced adhesives, self-healing adhesives and rubber-toughened adhesives using the multi-scale cohesive framework. We present the effect of several …
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Exploring the link between microstructure statistics and transverse ply fracture in carbon/epoxy composites
… which is inherently statistical. Transverse failure of unidirectional plies is particularly critical in composite laminates, as it is often a precursor for other, more catastrophic failure modes such as delamination and fiber breakage. Although it is possible to attempt to orient fibers …
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Tensile Testing of Cold-Applied Joint Sealants
… All the concrete samples failed due to adhesive failure, whereas some of the Sealant 1 glass samples failed due to adhesive failure at low peak loads and others failed due to a combination of adhesive and cohesive failure. Glass samples of Sealant 2 on the other hand showed just cohesive failure. …
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The Development of a Knowledge-Based Wax Deposition, Three Yield Stresses Model and Failure Mechanisms for Re-starting Petroleum Field Pipelines. Building on Chang and Boger’s Yield Stresses Model, Bidmus and Mehrotra’s Wax Deposition and Lee et al.’s Adhesive-Cohesive Failure Concepts to better Underpin Restart Operation of Waxy Crude Oil Pipelines
… using derivative data (dynamic fluidity and failure acceleration). In addition, calorimetry (DSC) and microscopy (CPM) helped extract WAT, the gel and pour points and link gel crystal structure and its yielding and breakage to rheological properties. The yielding stresses measured …
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Water based adhesive primers on aluminum substrates
… and the crack length increased. The locus of failure also changed from cohesive failure in the adhesive for the lower temperature aged samples to a mixed mode of cohesive failure and aluminum oxide-primer interfacial failure for the 80°C aged samples.
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Cohesive Modeling of Dynamic Fracture: Rate Dependence and Intersonic Crack Motion
… Results show that exclusive shear damage in the cohesive zone is responsible for intersonic crack propagation even though the external load comprises of both shear and tensile components. The situation is very different in the subsonic regime, where crack motion is a result of combined shear and …
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A controllably adhesive climbing robot using magnetorheological fluid
… experimentally measured and compared to existing cohesive failure fluid models of yield stress adhesion. These models were found to correlate with experimental results at yield stresses below 1.12 kPa. MR fluid samples activated to have yield stresses above 1.12 kPa were limited to an adhesive …
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Fracture analysis of carbon fiber/epoxy matrix interface through microbond and cruciform tests
… to characterize the normal and shear interfacial failure of a carbon fiber/epoxy matrix system. The first part of this study is devoted to the simulation of the microbond test, in which, a drop of epoxy deposited on a carbon fiber is subjected to a longitudinal load, which eventually leads to the …
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Experimental investigation of the effects of imperfections on the behavior of composite scarf joints
… the sensitivity of the overall response and failure behavior of composite scarf joints to the details of their geometry. Three parameters, considered to be manufacturing imperfections that could occur during the repair process, are examined: a through-thickness offset between the two …
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Lyocell Fiber-Reinforced Cellulose Ester Composites - Surface and Consolidation Considerations, and Properties
… fiber pull-out phenomenon observed after tensile failure in the unmodified fiber composites. This result was then supported in the second study in which similar unmodified fiber composites experienced very little fiber pull out with evidence of a large amount of cohesive failure of the matrix …
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Observing the Main Effects of Automotive Primers when Bonding to Polyvinylchloride
… observed. Obtaining high amounts of plastic cohesive failure depends more upon the bonded substrate, as many optimal factor levels were different.</p>
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Dynamic delamination of patterned thin films
… and finite element model for the thin film. Cohesive elements are introduced along the bi-material interface to capture the decohesion process. The important role of the inertia on the crack extension and the mixed-mode failure are demonstrated by observing the traction stress evolutions at …
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Effects of tooth quality, tooth structure, and cement mixing ratios on dental adhesion
… when the smear layer covers the dentin. Mixed failure modes were detected during dentin debonding while cohesive failure within the cement were observed during enamel debonding indicating that enamel bonded better to the cement than dentin did. Improper cement mixing decreased the bond strength …
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A feasibility study of the acousto-ultrasonic technique to assure the quality of adhesively bonded sheet metal
… These regions contribute to the mixed mode failure. A bond quality (BQ) model is suggested to take into account the mixed mode failure. Destructive testing results show fairly consistent correlation of BQ values with the breaking strength of the adhesive joint failing in mixed mode failure. …
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Synthesis and Characterization of Nitrile Containing Polysiloxanes and Their Corresponding Networks as Aircraft Sealant Materials
… nonpolar networks in hydrocarbons and Jet fuel. Cohesive failure was observed for the polar networks via metal to metal (Al foil substrate to Al and Ti adherends) 180° peel test. The PCPMS elastomers had average load values twice those of the PDMS networks independent of crosslink density.
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Development of high performance and efficient coating repair systems for offshore tropical marine environment
… concern on the studied coated surfaces as cohesive failure occurred on the pre-treatment layers rather than coating adhesion failure between the coating and the treated surface.
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Analysis of the Physiochemical Interactions of Recycled Materials in Concrete
… interfacial transition zone (ITZ) and to the cohesive failure of the asphalt. It is hypothesized that the detrimental impact on the ITZ is attributable to organic compounds leached from the asphalt in the high pH pore solution. This study proves the presence of organic compounds in the pore …
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Evaluating Thermal and Mechanical Properties of Electrically Conductive Adhesives for Electronic Applications
… aging, and there was a transition from cohesive failure to interfacial failure as aging continued. A comparative study of the durability of different conductive adhesive and substrate metallization combinations suggested that the resistance of the adhesive joints to moisture attack is …
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Design and characterization of aromatic thermosetting copolyester resin for polymer matrix nanocomposites
… >50 times repeated cycles through predominantly cohesive failure along with high glass transition temperature and bonding strength required for relevant application requirements. The solid-state bonding concept can also be utilized to join similar/dissimilar polymer composites and metal articles …
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The Thermal Stability of Anodic Oxide Coatings - Strength and Durability of Adhesively Bonded Ti-6Al-4V Alloy
… specimens suggest that the process leading to failure is the formation of fluorine-containing materials within the oxide, which weakens the adherend-adhesive bond. The formation of the fluorine components is facilitated by treatment at elevated temperatures. This study suggests that the …
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