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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

Optimization of the material selection process for cryogenic composite overwrapped pressure vessels

Dyess, Mark Vernon 03 May 2008 (has links)
The objective of this research was to develop a test methodology for the evaluation of materials for possible use in cryogenic composite overwrapped pressure vessels (COPVs). This paper investigates various micromechanical and macromechanical techniques to test the interaction between fibers and resins. Uniaxial tension testing was performed at ambient and cryogenic temperatures on neat resin samples, straight-sided composite specimens, and NOL ring specimens. COPVs were constructed and burst tested to provide a performance comparison. Results show resins suitable for use at cryogenic conditions display a LN2 temperature elongation to failure greater than 2% and an ambient temperature elastic modulus less than 35 MPa. NOL rings were determined to be the preferred composite test method rather than straight-sided specimens. Mechanical performance of the NOL rings compares well with actual COPV performance.
2

Mykensk alabastron från SH IIIC : Den mykenska samhällsförändringen genom keramiken / Mycenaean alabastron from LH IIIC : The societal change of the Mycenaean culture through the study of pottery

Cassman, Julia January 2022 (has links)
Mycenean society on mainland Greece started to decline with the collapse of the palatial system during the 13th century BC. Following the collapse was a big change in the ceramic repertoire of the Aegean area, this new period was later named the post-palatial period or late helladic IIIC which was based on the types of ceramics found during the period. The changes in the societies of the Aegean can be seen in the ceramics, which is one of the best-preserved materials from Mycenaean society. The changes are believed to have had a major impact on both the production and consumption of ceramic containers, which can be seen in the styles that were typical of the Greek mainland, but also in the spatial distribution and the use of ceramics. The purpose of this study is to analyze a ceramic object (an alabastron) from Uppsala University Museum Gustavianums antiquities collection and through the study find out how the object fits into the changes that took place in Mycenaean society around 1200 BC. The essay and the questions are mainly based on the ceramic object analyzed in the main part of the essay, where the purpose is to document and then analyze the vessel's manufacture, function, shape, decoration and the context. In this essay, theory and method is based on Panofskys’ framework for studies of iconography and iconology.
3

Mesomechanical Model for Failure Study of Two Dimensional Triaxial Braided Composite Materials

Li, Xuetao 01 December 2010 (has links)
No description available.

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