Global ETD Search
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 53 for “"kevlar"”.
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Thermoviscoelastic characterization and predictions of Kevlar/epoxy composite laminates
… the thermoviscoelastic characterization of Kevlar 49/Fiberite 7714A epoxy composite lamina and the development of a numerical procedure to predict the viscoelastic response of any general laminate constructed from the same material. The four orthotropic material properties, S₁₁, S₁₂, S₂₂, …
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A Study of Aerodynamics in Kevlar-Wall Test Sections
… to characterize the aerodynamic behavior of Kevlar-wall test sections and specifically those containing two-dimensional, lifting models. The performance of the Kevlar-wall test section can be evaluated against the standard of the hard-wall test section, which in the case of the Stability Wind …
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Characterization of structural changes in thermally enhanced Kevlar-29® Fiber
… enhanced compressive properties of heat-treated Kevlar-29® fibers. A novel theory was set forth that hydrogen bond disruption and concurrent misorientation of crystallites may account for the observed augmentation of compressive properties. To examine the said theory, virgin Kevlar-29® fibers …
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Impact and post-impact response of graphite/epoxy and Kevlar/epoxy structures
Vita. Title as it appeared in M.I.T. Graduate List, September 1987: Impact and post-impact response of laminated structures.
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Relationship between the processing parameters and tensile properties of air textured Kevlar yarns
… properties of continuous multifilament yarns. Kevlar, poly(p-phenylene terephthalamide) , due to its excellent mechanical and thermal properties has found wide ranging applications in protective clothing, however the filament has poor tactile properties. Air texturing could thus be the process …
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Understanding and Exploiting Wind Tunnels with Porous Flexible Walls for Aerodynamic Measurement
… porous, flexible walls formed from tensioned Kevlar has been characterized and new measurement techniques in such wind tunnels explored. The objective is to bring the aerodynamic capabilities of so-called Kevlar-wall test sections in-line with those of traditional solid-wall test sections. The …
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Polyimide/silica nanoparticle-modified epoxy resin and kevlar/glass fiber-reinforced polymer matrix composites for potential application in commercial aircraft radomes
… order to develop novel low-dielectric constant Kevlar and glass fiber polymer matrix composites via the wet lay-up and vacuum bagging techniques by utilizing epoxy resins modified with Polyimide (PI) and 2wt.% to 8wt.% of KH-550-modified silica nanoparticles. Dielectric constant tests revealed …
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Implementing Continuous Fiber Reinforcement for Concrete Additive Manufacturing
… designed an extruder for a continuous strand of Kevlar to be extruded alongside the concrete extrusion. Through controlling the speed at which the Kevlar extruder was linearly translated, different densities of Kevlar were created within two layers of concrete. These reinforced concrete pieces …
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Environmental effects on stitched RTM composites
… composites prepared from unstitched, Kevlar 29 stitched, and S-2 glass stitched uniweave fabric were determined. Data presented include compression strengths and compression-compression fatigue results for environmentally cycled and uncycled composites. Ten1perature cycling ranged from …
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Low velocity impact response of laminated textile coir-aramids/epoxy hybrid composites subjected to transverse penetration loading
… exists as a result of combining high performance Kevlar synthetic fibre and coir natural fibre in a specified laminated stacking sequence. In this research, quasi-static experiments were conducted at the speed of 1.25 mm/s, and low velocity impact tests were conducted using a 12.7 mm hemispherical …
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Transient moisture effects on the viscoelasticity of synthetic fibers and composites
… phenomenon. The materials studied included Kevlar® fibers, Kevlar® fiber reinforced composites, Technora fibers, poly(methyl methacrylate) (PMMA) fibers, and Nylon 6,6 fibers. Unidirectional ( 0° ) Kevlar® 49/7714 epoxy coupons undergoing desorption exhibited an increase in tensile and …
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Excitation of Acoustic Surface Waves by Turbulence
… metamaterial and flow were interfaced using a Kevlar covered single cavity whose Kevlar side faced the flow to ensure no significant disturbance to the flow and the other side was open to a quiescent (stationary) environment housing the metamaterial. Acoustic measurements were performed very …
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Aerodynamics and Acoustics of the Virginia Tech Stability Tunnel Anechoic System
… has been performed. This novel design utilizes Kevlar cloth to provide a stable flow boundary, which eliminates the need for a free jet and jet catcher. To test this concept a series of measurements were performed both to validate the reduction in overall test section noise levels and to …
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Environmental impact of various kayak core materials
… compares the environmental impact of fiberglass, Kevlar, carbon fiber, and cork. A kayak company is interested in using cork as a core material, and would like to claim that it is the most environmentally friendly of the four materials listed above. The efficacy of that claim is evaluated by …
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Designing, manufacturing, testing, and modeling motorcycle helmets using hybrid composite systems
… that minimize head injuries and fatalities. Kevlar® and carbon fiber-based materials are composites that are most often considered to absorb energy properly during a collision. Due to their extraordinary mechanical, electrical, and thermal properties and lightweight structure, they are widely …
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Multi-axial failure of high-performance fiber during transverse impact
… and razor blades using high-speed imaging. Kevlar® KM2, Dyneema®SK76 and AuTx have been impacted at velocities ranging from ∼100 m/s to ∼1200 m/s depending on projectile nose shape, with an emphasis set on determining the critical velocity wherein below said velocity significant development …
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The influence of fiber hybridisation on dynamic mechanical behavior of natural based composites
… higher costs of synthetic fibres (glass, carbon, kevlar fibre) used in fibre reinforced composite materials make it desirable to investigate natural fibres as a source of possible reinforcement in low-cost applications. Natural fibres are abundant and represent a significant cost reduction …
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Nondestructive Analysis of Advanced Aerospace Materials via Spectroscopy and Synchrotron Radiation
… as well as Synchrotron X-ray diffraction while Kevlar based fiber composites applicable to ballistic resistant armor were studied using Raman spectroscopy to investigate the mechanical state and corresponding damage and failure mechanisms. Piezospectroscopic studies on the stress state of the …
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Axial, flexural and torsional rigidities of two-dimensional braided fibre composite medical catheters
… (nuf12, nu f23, Gfl2, G23). Oversized braided (Kevlar 49 fibre and thermoset matrix) engineering model composite structures---or model catheters---have been used to verify the model. These model catheters have been produced on an existing braiding machine. Kevlar 49 fibre and epoxy resin have …
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