Structural design considerations for stretched-membrane heliostat reflector modules with stability and initial imperfection considerations

Abstract

This report extends the work of several previous reports that present the background leading to the development of stretched-membrane modules and analysis methods to study the structural response of the stretched-membrane module. Specifically, this report presents and discusses the design implications based on our analysis of single- or double-membrane concepts, and the amplification of initial imperfections and deflections caused by loading, which results from stability considerations. In this document, we present analysis results for both single- and double-membrane concepts corresponding to a range of design and loading conditions. Further, we show that stretched-membrane/frame combinations respond quite differently to external loads than can be inferred by studying the decoupled frame and membrane independently. Thus the coupled membrane/frame problem should be considered to assure an accurate description of its response. For idealized configurations and loadings, we discuss the relative merits of various design features for both of these designs. In addition, we studied the structural stability (i.e., the tendency of structural deformation to grow with little increase in applied load) of the tensioned-membrane, compressed-frame combination. Moreover, we demonstrate how stability considerations are important in determining the amplification of both initial displacement imperfection and the deformations caused by wind and weight loading onmore » the structure.« less