In this analytical investigation of the initial response of a thin, circular, homogeneous, and isotropic ring to a transverse shock pulse, the radial and tangential components of displacement and velocity are found in series form by use of Duhamel's integral. A plane shock front is assumed to propagate normal to a diameter of the ring with constant linear velocity and to be followed by a parabolic decay. It is also assumed that the motion of the ring does not influence the pressure of the wave and that the wave exerts only radial forces on the ring. Classical, small-deflection linear theory, neglecting rotatory inertia and shear effects, is used in conjunction with the classical treatment of distinct extensional and flexural modes. For the stated loading scheme, Duhamel 's integral cannot be obtained in closed form; however, by use of numerical integration an example problem is solved and the resulting displacement and velocity histories are plotted. The flexural velocity showed unexpectedly large values at relatively late times. An alternate analytical solution using a double Fourier series is also developed, but no numerical results were determined. The flexural response from the solution of an approximate problem consisting of a moving concentrated force on a ring was also investigated to help explain this unexpected response. An area deserving further consideration is raised by the problem of the relative importance of using a sweeping type load as opposed to using the mathematically simpler all-at-once type loading. / M.S.

no abstract provided by the author / Master of Science

A laser-driven miniflyer system is built in design similar to those at the Los Alamos National Laboratory and Eglin Air Force Base. It is composed of three parts: laser drive source, impact experiment assembly, and diagnostics. The laser drive source is a Nd:YAG laser operating at 1064nm at a maximum energy of 3 J. The impact experiment assembly consists of a BK7 substrate on to which is deposited an ablation layer consisting of carbon, alumina, and aluminum. Mounted on the ablation layer is a metal foil (flyer). The carbon in the ablation layer absorbs the laser energy to form a rapidly expanding plasma. The alumina and aluminum layers provide thermal insulation and also contain the plasma. The set-up is expected to provide flyer velocities in the range of 100 to 1000 m/s. Diagnostics consist of a Photonic Doppler Velocimetry (PDV) system that uses Doppler-shifted coherent laser light to measure the instantaneous velocity of a moving surface, as well as velocity dispersions caused by mechanical or material heterogeneities. This thesis will provide a description of the set-up of the laser-driven miniflyer system, as well as an evaluation of the flyer velocity, measured using the PDV system, as a function of laser energy. The flyer velocity trends will be used in order to characterize and calibrate the system. A manual providing system operation instructions will also be included to serve future users of this miniflyer system

Approved for public release; distribution is unlimited. / During World War II many surface combatants were damaged or severely crippled by close-proximity underwater explosions from ordnance that had actually missed their target. Since this time all new classes of combatants have been required to conduct shock trial tests on the lead ship of the class in order to test the survivability of mission essential equipment in a severe shock environment. While these tests are extremely important in determining the vulnerabilities of a surface ship, they require an extensive amount of preparation, manhours, and money. Furthermore, these tests present an obvious danger to the crew on board, the ship itself, and any marine life in the vicinity. Creating a virtual shock environment by use of a computer to model the ship structure and the surrounding fluid presents a valuable design tool and an attractive alternative to these tests. This thesis examines the accuracy of shock simulation using the shock trials conducted on USS WINSTON S. CHURCHILL (DDG 81) in 2001. Specifically, all three explosions that DDG 81 was subjected to are simulated and the resulting predictions compared with the actual shock trial data. The effects of fluid volume size, mesh density, mesh quality, and shot location are investigated. / Lieutenant, United States Navy

Thesis (M.S.)--State University of New York at Binghamton, Department of Mechanical Engineering, 2005. / Includes bibliographical references (p. 78-80).

Heterogeneities at the meso-scale strongly influence the shock compression response of composite materials. These heterogeneities arise from both structural variations and differing physical/mechanical properties between constituents. In mixtures of reactive materials, such as Ni and Al, the meso-scale heterogeneities greatly affect component mixing and activation, which, in turn, can induce a chemical reaction. Cold-rolled multilayered composites of Ni and Al provide a unique system for studying the effects of material heterogeneities on a propagating shock wave, due to their full density, periodic layering, and intimate particle contacts. Computational analysis of the shock compression response of fully dense Ni/Al multilayered composites is performed with real, heterogeneous microstructures, obtained from optical microscopy, using the Eulerian hydrocode CTH. Changes in the orientation, density, structure, and strength of the material interfaces, as well as the strength of the constituents, are used to understand the influence microstructure plays on the multilayered composite response at high strain rates. The results show a marked difference in the dissipation and dispersion of the shock wave as the underlying microstructure varies. These variations can be attributed to the development of two-dimensional effects and the nature of the wave reflections and interactions. Validation of the computational results is then obtained through time-resolved measurements (VISAR, PDV, and PVDF stress gauges) performed during uniaxial strain plate-on-plate impact experiments. The experimental results prove that the computational method accurately represents the multilayered composites, thereby justifying the conclusions and trends extracted from the simulations. The reaction response of cold-rolled multilayer composites is also investigated and characterized using uniaxial stress rod-on-anvil impact experiments through post-mortem microscopy and x-ray diffraction. This extensive understanding of the shock compression response of the multilayers systems is contrasted with other composites of Ni and Al, including shock consolidated and pressed (porous) powder compacts. A comprehensive design space is then developed to assist in the understanding and design of Ni/Al composites under conditions of high pressure shock compression. Research funded by ONR/MURI grant No. N00014-07-1-0740.

No description available.

Thesis (Ph. D.)--University of Missouri-Columbia, 2001. / Typescript. Vita. Includes bibliographical references (leaves 100-104). Also available on the Internet.

Thesis (Ph. D.)--University of Missouri-Columbia, 2001. / Typescript. Vita. Includes bibliographical references (leaves 100-104). Also available on the Internet.

Thesis (Mechanical Engineer and M.S. in Mechanical Engineering)--Naval Postgraduate School, June 2003. / Thesis advisor(s): Young S. Shin. Includes bibliographical references (p. 161-162). Also available online.