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contributor authorL. M. Murphy
date accessioned2017-05-08T23:25:40Z
date available2017-05-08T23:25:40Z
date copyrightMay, 1987
date issued1987
identifier issn0199-6231
identifier otherJSEEDO-28197#111_1.pdf
identifier urihttp://yetl.yabesh.ir/yetl/handle/yetl/103005
description abstractLarge deformable membranes are currently used as optical reflector surfaces for solar concentrators. In this paper, we study moderate axisymmetric deformations of optical membrane surfaces and their impact on the macroscopic optical quality of the deformed surface. A uniform pressure loading applied to an initially flat membrane surface is assumed in attaining the final concentrator surface shape. The problem is important in the design of focusing stretched-membrane heliostat modules. Insights into the design of stretched-membrane parabolic dish reflectors also result from this work. This paper presents several simple design and sizing relationships, based on a nonlinear variational principle, in terms of common engineering parameters. Good approximate predictions of the nonlinear load-deformation response and the stress state in the membrane are derived; simple but accurate predictions for membrane surface slope and nominal focal length also result. The phenomena that lead to deviation of the surface shape from the desired parabolic reflector shape are identified and design procedures to minimize those deviations are deduced. Results show that the macroscopic optical surface quality, for a given nominal f /D (concentrator focal length/diameter), is highly dependent on the non-dimensionalized membrane stiffness parameter, Et /T o (membrane modulus × thickness/initial tension). Further, for the heliostat cases of interest, the focal-length variations relative to the desired parabolic shape were shown to be about ±5 percent about the nominal value.
publisherThe American Society of Mechanical Engineers (ASME)
titleModerate Axisymmetric Deformations of Optical Membrane Surfaces
typeJournal Paper
journal volume109
journal issue2
journal titleJournal of Solar Energy Engineering
identifier doi10.1115/1.3268187
journal fristpage111
journal lastpage120
identifier eissn1528-8986
keywordsDeformation
keywordsMembranes
keywordsShapes
keywordsDesign
keywordsStress
keywordsOptical mirrors
keywordsVariational principles
keywordsSolar energy concentrators
keywordsStiffness
keywordsTension
keywordsThickness
keywordsSurface quality AND Pressure
treeJournal of Solar Energy Engineering:;1987:;volume( 109 ):;issue: 002
contenttypeFulltext


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