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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.
1

Effect of composite microstructure on electrical and mechanical properties of poly(vinyl acetate) composites with carbon black and clay.

Miriyala, Sethu M. 15 May 2009 (has links)
The electrical and mechanical behavior of carbon black filled poly(vinyl acetate) latex-based and solution-based polymer composites was examined. A set of experiments were performed to distinguish composites with a segregated network (emulsion-based) from those with random dispersion (solution-based) of the filler. The percolation thresholds for the emulsion-based composites were near 1.2 vol% carbon black, while the solution-based composites were around 8.2 vol% carbon black. This difference is due to the segregated network formation, which leads to excluded volume effects in emulsion-based systems. This excluded volume created by the solid polymer particles forces the carbon black particles into conductive pathways at low concentration. In the solution-based case, fully solvated polymer results in a random dispersion of carbon black. The segregated network composite also shows significant improvement in both electrical conductivity and storage modulus with low carbon black loading, while the solution-based composite achieves significant property enhancements at higher carbon black loading because of the greater percolation threshold. The effect of clay in both emulsion and solution-based composites with carbon black was also studied by preparing composites with three clay concentrations (0.2, 0.4 and 2 wt%). In emulsion-based composites, low clay concentration reduced the percolation threshold from 1.2 vol% to 0.8 vol% carbon black, but with solution-based composites clay increased the percolation threshold from 8.2 vol% to 11.7 vol% carbon black. It is assumed that clay helps to force the carbon black particles into the conductive pathways in the emulsion-based composites. In solution-base composites, clay improves the dispersion of carbon black, thereby destroying the carbon black network and reducing conductivity and storage modulus. The storage modulus in emulsion-based composites improved with 0.2 wt% clay but greater clay concentration resulted in a drop in modulus due to porosity from excess excluded volume effects.
2

Characterization of Fibre Reinforcements for Non-structural Composite Parts

Badripour, Yousef 15 November 2018 (has links)
Fibre reinforced composite materials have attracted attention from industry and academia due to their high specific stiffness and strength. Commonly used manufacturing processes include the Liquid Composite Moulding (LCM) group of processes, where a liquid polymer resin impregnates a dry preform that is prepared in advance. The consistency of the resin infusion process and properties of the final composite are highly dependent on preform quality and reproducibility. Preform quality, in turn, depends on a process called draping. This work aims at understanding and developing quantitative knowledge of key elements of reinforcement behaviour during preforming. Testing characterization methods for dry fabrics are introduced and discussed. Moreover, the thesis probes relations between fabric properties such as their architecture and fibre type, and elements of their draping and preforming behaviour such as bending stiffness and in-plane shear properties of the dry fabrics. Most materials used in this work were selected by the industrial partner, Hutchinson Aerospace and Industry, based in Montreal. Some experiments were conducted using Hutchinson’s characterization devices, which are introduced in the relevant chapters.
3

Modélisation des caractéristiques mécaniques et études expérimentales de l'endommagement d'un composite.

Dody, Michel, January 1900 (has links)
Th. univ.--Sci. ing.--Besançon, 1985. N°: 6.
4

Effect of composite microstructure on electrical and mechanical properties of poly(vinyl acetate) composites with carbon black and clay.

Miriyala, Sethu M. 15 May 2009 (has links)
The electrical and mechanical behavior of carbon black filled poly(vinyl acetate) latex-based and solution-based polymer composites was examined. A set of experiments were performed to distinguish composites with a segregated network (emulsion-based) from those with random dispersion (solution-based) of the filler. The percolation thresholds for the emulsion-based composites were near 1.2 vol% carbon black, while the solution-based composites were around 8.2 vol% carbon black. This difference is due to the segregated network formation, which leads to excluded volume effects in emulsion-based systems. This excluded volume created by the solid polymer particles forces the carbon black particles into conductive pathways at low concentration. In the solution-based case, fully solvated polymer results in a random dispersion of carbon black. The segregated network composite also shows significant improvement in both electrical conductivity and storage modulus with low carbon black loading, while the solution-based composite achieves significant property enhancements at higher carbon black loading because of the greater percolation threshold. The effect of clay in both emulsion and solution-based composites with carbon black was also studied by preparing composites with three clay concentrations (0.2, 0.4 and 2 wt%). In emulsion-based composites, low clay concentration reduced the percolation threshold from 1.2 vol% to 0.8 vol% carbon black, but with solution-based composites clay increased the percolation threshold from 8.2 vol% to 11.7 vol% carbon black. It is assumed that clay helps to force the carbon black particles into the conductive pathways in the emulsion-based composites. In solution-base composites, clay improves the dispersion of carbon black, thereby destroying the carbon black network and reducing conductivity and storage modulus. The storage modulus in emulsion-based composites improved with 0.2 wt% clay but greater clay concentration resulted in a drop in modulus due to porosity from excess excluded volume effects.
5

Etude du comportement des structures composites endommagées par un impact basse vitesse Application aux structures aéronautiques /

Eve, Olivier. Zeghloul, Abderrahim January 1999 (has links) (PDF)
Thèse doctorat : Sciences de l'ingénieur. Génie mécanique : Metz : 1999. / Bibliogr. p. 149-159.
6

Compression et microflambage dans les matériaux composites à fibres longues

Grandidier, Jean-Claude. Potier-Ferry, Michel. January 1991 (has links) (PDF)
Thèse de doctorat : Physique : Metz : 1991. / 1991METZ004S. 62 ref.
7

Thermal analysis of the continuous filament winding process

James, Darryl L. 12 1900 (has links)
No description available.
8

On-line consolidation of thermoplastic towpreg composites in filament winding

Wagner, Philip Cameron 12 1900 (has links)
No description available.
9

A combined experimental analytical methodology for characterizing the thermoviscoplastic deformation of a metal matrix composite /

Rogacki, John R. January 1992 (has links)
Thesis (Ph. D.)--University of Washington, 1992. / Vita. Includes bibliographical references (leaves [74]-80).
10

Durability of polymeric composites after elevated temperature aging /

Poole, Eric L. January 1997 (has links)
Thesis (Ph. D.)--University of Washington, 1997. / Vita. Includes bibliographical references (leaves [134]-141).

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