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 15 of 15 for “"Pre Strain"”.
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The Effect of Pre-strain and Strain Path Changes on Ductile Fracture
… The mechanical behavior of materials undergoing strain path changes can be very different from those deformed in a given direction to fracture. The work presented here employed laser drilled model materials to better understand the effect of pre-strains and strain path changes on void growth and …
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The effect of pre-strain on the fracture toughness of line pipe steel
… which typically limit the applied stresses and strains to below yield. Pipelines may be subjected to higher plastic strains before they enter service and during operation, either intentionally, as a result of the method of installation, or a requirement of the design and operation, or …
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Premature cleavage of ship plating under reversed bending
… design data to be used by the industry in predicting the effects of extreme loads such as accidents at sea or earthquakes. Since cleavage is more dangerous than ductile fracture, attention was focused on conditions controlling cleavage fracture. A careful inspection of damaged components of …
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The design and performance of non-linear vibration isolating materials.
… elastic modulus, cellular structure, static pre-strain. In many end use situations the pre-compressions and dynamic amplitudes are large and the material operates in a non-linear regime. The effects of non-linear material behaviour on the performance of systems employing cushion foams has not …
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The Variability of Strains in Bolts and the Effect on Preload in Jointed Structure
… amount of uncertainty in the resulting bolt preload. With the inability to determine the preload in bolted structures precisely, overdesign is necessary for bolts to meet safety requirements and prevent jointed structures from looseness failure. A series of comparative experiments are …
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Resetting microstructures and properties in TRIP-assisted advanced high strength steels
… steel, such as the effects of composition and pre-strain, to increase the kinetics of the underlying transformations. This study demonstrates that with proper microstructure design, the resetting process could be completed within minutes following a critical level of deformation.
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Bauschinger effect in Nb and V microalloyed line pipe steels
… to provide grain refinement, solid solution and precipitation strengthening. During the UOE forming of large diameter (more than 400 mm) welded pipes the strength drop from plate to pipe, as a result of reverse deformation (the Bauschinger effect), depends on steel grade, namely microalloying …
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Smart Surgical Needle Actuated by Shape Memory Alloys for Percutaneous Procedures
… in most of these procedures is to attain a precise navigation through tissue reaching target locations. Insufficient accuracy using conventional surgical needles motivated researchers to provide actuation forces to the needle’s body for compensating the possible errors of …
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Strechable crumpled graphene photodetector with plasmonically-enhanced photoresponsivity
… mechanical stretchability up to 200% tensile strain. We achieved the plasmonically enhanced optical absorption of graphene-based photodetector by using a hybrid structure of graphene-AuNPs. We crumpled the hybrid structure to realize mechanical stretchability and further enhancement of the …
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Modeling and Simulation of Viscoplasticity, Recrystallization, and Softening of Alloyed Steel During Hot Rolling Process
… metal during hot rolling process. Gleeble hot compression tests were performed to provide experimental stress-strain curves at different temperatures and strain rates. An inverse finite element analysis was performed to calibrate the experimental curves. Viscoplastic models including a …
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The effect of shear on the stability and dynamic properties of elastic bodies
… material which has been subjected to a static pre-strain corresponding to simple shear. Initially we consider a prototype problem wherein the theory of incremental motions provides the mechanism for analyzing Rayleigh waves propagating along the surface of an incompressible elastic half-space. …
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Shape memory alloy induced wing warping for a small unmanned aerial vehicle
… A conceptual design is introduced in which pre-strained Nitinol wires are attached to the surface of the wing. When the resistively heated wires pass a transition temperature, a phase change occurs in the wires and they contract to recover the pre-strain. As the wires contract, they twist …
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Design tools and predictions for nonlinear elastic solids in soft machine design
… 1), identify limitations (Chapter 1), and present new design tools (Chapter 2) for rheologically-complex soft solids. We identify material properties and features that may be vital for optimal soft machine performance, such as intrinsic nonlinearities, variable stiffness, and strain to …
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Ductile fracture after complex loading histories : experimental investigation and constitutive modeling
… practice, sheet metal often fails after complex strain paths that deviate substantially from the widely studied proportional loading paths. Different from previous works on the ductile fracture of sheet metal, this thesis research addresses the experimental and modeling issues related to the …
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Modeling of mechanical energy dissipation of low-dimensional resonators
… have opened up new possibilities in high-precision sensing, signal processing, and studies of fundamental physical phenomena. In the heart of the NEMS is a vibrating mechanical element, known as the resonator. The performance of the NEMS critically depends on the mechanical energy …