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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.
171

Comparison of static and dynamic test methods for determining the stiffness properties of graphite/epoxy laminates

Turner, Michael Derryck January 1979 (has links)
Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 1979. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND AERONAUTICS. / Includes bibliographical references. / by Michael Derryck Turner. / M.S.
172

Design, manufacturing, and testing of high speed rotating graphite/epoxy shafts

Bauchau, Olivier André January 1981 (has links)
Thesis (Sc.D.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 1981. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND AERO. / Includes bibliographical references. / by Olivier Andre Bauchau. / Sc.D.
173

The catastrophic failure of pressurized graphite/epoxy cylinders

Graves, Michael Jeffrey January 1982 (has links)
Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 1982. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND AERO / Includes bibliographical references. / by Michael Jeffrey Graves. / Ph.D.
174

Spatial variability characterisation of laminated composites

Naskar, Susmita January 2018 (has links)
Advanced lightweight structural materials like composites are being increasingly utilized in various engineering applications due to high specific strength and stiffness with tailorable properties. Even though composites have the advantage of modulating a large number of design parameters to achieve various application-specific requirements, this concurrently brings the challenge of dealing with inevitable uncertainties during manufacturing and service-life conditions. This dissertation focuses on practically relevant modelling of random spatial variability coupled with the influence of damage to quantify the effect of source-uncertainties following an efficient surrogate based framework. Layer-wise random variable based approach and the random field based approaches of uncertainty modelling are investigated to quantify the stochastic dynamics and stability characteristics of in a probabilistic multi-scale framework. A novel concept of stochastic representative volume element is proposed to consider the spatially varying structural attributes effectively. A physically relevant random field based modelling approach with correlated material properties is adopted based on the Karhunen-Loève expansion. To understand the relative influences, sensitivity of the stochastic input parameters are analyzed for the global structural responses of composite laminates considering micro and macro mechanical properties separately. Besides the conventional sources of uncertainty in material and structural properties, another source of uncertainty is considered in the form of noise. Besides probabilistic analysis, this dissertation proposes a fuzzy representative volume element based approach for modelling spatial variability in non-probabilistic analysis for the cases where statistical distributions of the stochastic input parameters are not available. The results reveal that stochasticity affects the system performance significantly. A notable difference in the global stochastic behaviour is identified depending upon the adopted uncertainty modeling approach. Thus, it is imperative to appropriately model the sourceuncertainties during the analysis and design process. The dissertation provides comprehensive insights on the effect of source-uncertainties on composites following an efficient, yet practically relevant modelling approach.
175

Placas laminadas em materiais compostos de fibras longas: propriedades termoelásticas dos materiais constituintes; propriedades equivalentes das lâminas; critérios de ruptura e análise pelo método dos elementos finitos / Long fiber composite materials laminated plates: constituent materials properties; laminae equivalents properties; failure criteria and finite element method analysis

Magagnin Filho, Nilson 29 April 1996 (has links)
Os materiais compostos de fibras longas vêm se destacando entre o conjunto de novos materiais em desenvolvimento, com larga aplicação na indústria e também na construção civil. Elabora. se aqui um texto introdutório no campo das placas laminadas constituídas de lâminas em compostos de fibras longas. A partir das propriedades dos materiais constituintes, fibra e matriz, são apresentadas as teorias para a determinação das propriedades equivalentes das lâminas. A teoria da anisotropia elástica é formulada e a teoria dos laminados em flexão é desenvolvida. Conclusões com respeito ao acoplamento de esforços em tais estruturas são mostradas. Os modos básicos de ruptura da fibra, matriz e da interface entre ambas são apresentados, bem como os modos básicos de delaminação. Alguns critérios de ruptura são mostrados, assim como um critério de escoamento. Ao fim alguns exemplos ilustram a análise pelo método dos elementos finitos de tais estruturas feita por programa disponível em literatura, com a implementação de subrotina para análise da temperatura. / Long fiber composite materials have been standing out among the group of new materials in development with wide industrial application and also in civil construccion. Here is elaborated an introductory text in laminated plates field constituted of long fiber composite laminae. Starting from constituent materials properties, fiber and matrix, the theories for determination of laminae equivalent properties are presented. Elastic anisotropy theory is formulated and the bending laminated theory is developed. Conclusions about the coupling efforts in such structures are showed. Fiber, matrix and the interface between both failure basic modes are presented, as well as delamination basic modes. Some failure criteria are showed, as well as a yielding criteria. At the end some examples illustrate the finite element method analysis of such structures made by available literature programme with temperature analysis subroutine implementation.
176

Estudo de emendas dentadas em Madeira Laminada Colada (MLC): avaliação de método de ensaio / not available

Alcebíades Negrão Macêdo 20 September 1996 (has links)
Este trabalho consiste no estudo teórico e experimental das emendas dentadas em madeira laminada colada (MLC), cujo objetivo principal é avaliar o método proposto no Projeto da Nova Norma Brasileira PNBR 7190 (1996) para a caracterização da MLC, com ênfase às emendas dentadas. As espécies de madeira estudadas foram o Pinus elliottii e o Eucalipto grandis e o adesivo utilizado foi o CASCOPHEN RS-216, à base de resorcinol, produzido pela Alba Química Indústria e Comércio Ltda. A emenda dentada usada no estudo foi a correspondente ao comprimento de 20 mm da DIN 68140, geometria esta adotada pelo parque produtor de MLC no país. Nos ensaios são avaliadas as resistências ao cisalhamento na lâmina de cola, a tração normal à lâmina de cola e a resistência a tração das emendas dentadas. O desempenho das ligações foi avaliado em função da relação entre os valores obtidos nos ensaios com madeira colada e madeira maciça, bem como pelo modo de ruptura dos mesmos. Como conclusão obteve-se que o processo de colagem adotado foi bem sucedido para todos as amostras de caracterização da MLC, independente da espécie de madeira e do tipo de ruptura obtido. O método proposto no Projeto da Nova Norma Brasileira PNBR 7190 (1996) mostrou-se adequado para a caracterização das propriedades de resistência da MLC. / This work consist in the theoretical and experimental study of finger joints in glued laminated timber (GLULAM), with main objective to evaluate the method proposed in the New Brazilian Draft Code PNBR 7190 (1996) to characterization of GLULAM, with emphasis to finger joints. The species of wood studied were the Pinus elliottii and Eucalipto grandis and the adhesive was the CASCOPHEN RS-216, resorcinol-based, produced by Alba Química Indústria e Comércio Ltda. The geometry of finger joint used in the study was the correspondent to DIN 68140, this is the adopted by producer park of GLULAM in the country. In the tests were evaluated the shear resistance of glue lamina, the perpendicular tension resistance of glue lamina and parallel to grain tension resistance of finger joints. The performance of jointing was evaluated as a function of the relation between the values obtained in the tests with glued wood and clear wood, as well as rupture mode. Concluding remarks that gluing process adopted was well successful to all specimens of wood specie and rupture mode. The method proposed by New Brazilian Draft Code PNBR 7190 (1996) is adequate to characterization of the resistance properties of GLULAM.
177

Low-cycle fatigue study of fiberglass-reinforced plastic laminates.

Struminsky, Eugene. January 1971 (has links)
No description available.
178

The effects of curvature on axial flux machine cores

Hewitt, Andrew January 2005 (has links)
This work is an investigation into the curvature related potential for flux to flow in the radial direction in the back-iron of laminated axial flux machine cores. Analytical and numerical models are presented. Analysis based on these models has shown that, in practical axial flux machines, the radial component of the flux density can be neglected with respect to the flux density distribution in the core back-iron. It has also been found that if the core permeability, core conductivity and number of poles are sufficiently high then power loss due to curvature related cross-lamination flux is negligible compared to normal eddy current losses. A closed form expression to predict losses due to curvature related radial flux is also presented. This expression allows axial flux machine designers to make quick assessment of the need to consider these losses when designing axial flux machines.
179

Modeling of composite laminates subjected to multiaxial loadings

Zand, Behrad, January 2007 (has links)
Thesis (Ph. D.)--Ohio State University, 2007. / Title from first page of PDF file. Includes bibliographical references (p. 291-304).
180

Strain Rate-Dependent Behavior of Laminated Strand Lumber

Syron, William Donald January 2010 (has links) (PDF)
No description available.

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