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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.

Unidirectional solidification of Y O (CeO )-Mo and Y O (CeO )-W composites.

Graves, Jeffrey Arthur 12 1900 (has links)
No description available.

A modified rail shear test for thin composite plates

Grayson, John Michael 05 1900 (has links)
No description available.

Structural analysis of stretched membrane reflector modules using advanced composites

Ganapathy, Visvanathan, 1957- January 1987 (has links)
The concept of achieving low cost (≈ $20/m²) and ultra low weight (5 kg/m²) for heliostats is explored theoretically and experimentally. The objective of this work is to significantly improve the cost and performance of the structure under concern, without sacrificing strength and efficiency. The focus is on an innovative design of stretched-membrane heliostats. A reflective membrane of thin film is supported by a taut fishnet structural membrane consisting of graphite fiber-polymer matrix composite. The reflective and structural membranes are attached to a ring frame made of wood. The nonlinear problem of stress-strain analysis is formulated and solved using the finite-element code NASTRAN. The analysis is done for loads which include the initial stretching of the film and structural membrane and the pressure load due to wind. The scope of the present work is limited to analyzing the structural deformation behavior of flat-plate heliostats and partial extension to parabolic and semi-hemispherical dish reflectors.

Transient response of laminated composites with subsurface cracks.

Karim, Md. Rezaul. January 1988 (has links)
The dynamic response of subsurface cracks in fiber reinforced composites is analytically studied. The response of layered half-space and three-layered plate with two interface cracks excited by a plane SH-wave and line load respectively are studied by formulating the problem as integral equations in the frequency domain. The governing equations along with boundary, regularity and continuity conditions across the interface are reduced to a coupled set of singular integral equations by using Betti's reciprocal theorem along with the Green's functions. In addition, the transient response of an orthotropic half-space with a subsurface crack subjected to inplane line load at an arbitrary angle is analyzed. Two new Green's functions for the uncracked medium are developed and used along with the representation theorem to derive the scattered field. Satisfaction of the traction free condition at the crack surfaces gives rise to a system of singular integral equations. Singular integrals involved in the analysis are computed numerically by removing the poles. Part of the integrals containing the poles are then obtained analytically by using residue theorem. The solution of singular integral equations are obtained by expanding the unknown crack opening displacements (COD) in terms of a complete set of Chebychev polynomials. The problem is first solved in the frequency domain, the time histories are then obtained numerically by inverting the spectra via Fast Fourier Transform (FFT) routine. Numerical results are presented for isotropic and anisotropic materials for several different crack geometries. The results show significant influence of crack geometries and material properties on the COD and surface response of composites.

Design and evaluation of test apparatuses and methods for extension-twist coupled laminates

Hooke, David A. 12 1900 (has links)
No description available.

Energy-dissipating tensile composite members with progressive failure

Dancila, Dragos Stefan 05 1900 (has links)
No description available.

Impact response of a laminated beam on an elastic foundation

Tudela, Mark A. 05 1900 (has links)
No description available.

The effect of microstructure on the mechanical properties of a 30% titanium diboride/70% alumina composite

Carney, Alison Fox 08 1900 (has links)
No description available.

Structural Testing and Analysis of Hybrrid Composite/Metal Joints for High-Speed Marine Structures

Kabche, Jean Paul January 2006 (has links) (PDF)
No description available.

The accelerated characterization of viscoelastic composite materials

Griffith, William I. 16 September 2009 (has links)
A brief review of necessary fundamentals relative to composite materials and viscoelasticity is provided. Subsequently the accelerated characterization techniques of Time Temperature Superposition and Time Temperature Stress Superposition are treated in detail. An experimental procedure for applying the latter to composites is given along with results obtained on a particular T300/934 graphite/epoxy. The accelerated characterization predictions are found in good agreement with actual long term tests. A postcuring phenomenon is discussed that necessitates thermal conditioning of the specimen prior to testing. A closely related phenomenon of physical aging is described. The effect of each on the glass transition temperature and strength is discussed. Creep rupture results are provided for a variety of geometries and temperatures for T300/934 graphite/epoxy. The results are found to compare reasonably with a modified kinetic rate theory. / Ph. D.

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