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Full-Text Articles in Engineering

The Cryogenic Bonding Evaluation At The Metallic-Composite Interface Of A Composite Overwrapped Pressure Vessel With Additional Impact Investigation, Eric A. Clark Dec 2009

The Cryogenic Bonding Evaluation At The Metallic-Composite Interface Of A Composite Overwrapped Pressure Vessel With Additional Impact Investigation, Eric A. Clark

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

A bonding evaluation that investigated the cryogenic tensile strength of several different adhesives / resins was performed. The test materials consisted of 6061 aluminum test pieces adhered to a wet-wound graphite laminate in order to simulate the bond created at the liner-composite interface of an aluminum lined composite overwrapped pressure vessel. It was found that for cryogenic applications, a flexible, low modulus resin system must be used. Additionally, the samples prepared with a thin layer of cured resin – or prebond – performed significantly better than those without. It was found that it is critical that the prebond surface must …


Multiscale Modeling Of Impact On Heterogeneous Viscoelastic Solids With Evolving Microcracks, Flavio V. Souza Apr 2009

Multiscale Modeling Of Impact On Heterogeneous Viscoelastic Solids With Evolving Microcracks, Flavio V. Souza

Department of Engineering Mechanics: Dissertations, Theses, and Student Research

Multiscale computational techniques play a major role in solving problems related to viscoelastic composite materials due to the complexities inherent to these materials. In the present work, a numerical procedure for multiscale modeling of impact on heterogeneous viscoelastic solids containing evolving microcracks is proposed in which the (global scale) homogenized viscoelastic incremental constitutive equations have the same form as the local scale viscoelastic incremental constitutive equations, but the homogenized tangent constitutive tensor and the homogenized incremental history dependent stress tensor depend on the amount of damage accumulated at the local scale. Furthermore, the developed technique allows the computation of the …


The Effect Of Silicon Content On Impact Toughness Of T91 Grade Steels, Ajit K. Roy, Pankaj Kumar, Debajyoti Maitra Mar 2009

The Effect Of Silicon Content On Impact Toughness Of T91 Grade Steels, Ajit K. Roy, Pankaj Kumar, Debajyoti Maitra

Mechanical Engineering Faculty Research

The impact resistance of silicon (Si)-containing modified 9Cr-1Mo steels has been investigated within a temperature regime of -40 to 440°C using the Charpy method. The results indicate that the energies absorbed in fracturing the tested specimens were substantially lower at temperatures of -40, 25, and 75°C compared to those at elevated temperatures. Lower impact energies and higher ductile-to-brittle-transition-temperatures (DBTTs) were observed with the steels containing 1.5 and 1.9 wt.% Si. The steels containing higher Si levels exhibited both ductile and brittle failures at elevated temperatures. However, at lower temperatures, brittle failures characterized by cleavage and intergranular cracking were observed for …


Response Of Rigid Polyurethane Foam-Filled Steel Hollow Columns Under Low Velocity Impact, Alexander Remennikov, Brian Uy, Kong Sih Ying Jan 2009

Response Of Rigid Polyurethane Foam-Filled Steel Hollow Columns Under Low Velocity Impact, Alexander Remennikov, Brian Uy, Kong Sih Ying

Faculty of Engineering - Papers (Archive)

This paper presents the results of experimental investigations on rigid polyurethane foam-filled steel hollow columns under dynamic loading conditions.


Mitigation Of Impact Vibrations Using Impedance Mismatch In Cylindrical Structures, Sachiko Sueki Jan 2009

Mitigation Of Impact Vibrations Using Impedance Mismatch In Cylindrical Structures, Sachiko Sueki

UNLV Theses, Dissertations, Professional Papers, and Capstones

The focus of this work is to study the phenomenon of material impedance mismatch to determine its effect on the mitigation of high frequency accelerations in projectile and long bar structures within linear ranges of materials. In this study, the acceleration responses of structures with various materials and material combinations were studied experimentally, numerically and by the Finite Element Analysis (FEA). Air-gun tests conducted by the US Army Research Laboratory were modeled using FEA to simulate the acceleration pulse and shock waves experienced by artillery components during a launch. After the prototype of projectile was selected, further studies were conducted …