Structural Modeling of a Five-Meter Thin-Film Inflatable Antenna/Concentrator
Inflatable structures have been the subject of renewed interest in recent years for space applications such as communications antennas, solar thermal propulsion, and space solar power. A major advantage of using inflatable structures in space is their extremely light weight. An obvious second advantage is on-orbit deployability and related space savings in the launch configuration. A recent technology demonstrator flight for inflatable structures was the Inflatable Antenna Experiment (IAE) that was deployed on orbit from the Shuttle Orbiter. Although difficulty was encountered in the inflation/deployment phase, the flight was successful overall and provided valuable experience in the use of such structures. Several papers on static structural analysis of inflated cylinders have been written, describing different techniques such as linear shell theory, and nonlinear and variational methods, but very little work had been done in dynamics of inflatable structures until recent years. In 1988 Leonard indicated that elastic beam bending modes could be utilized in approximating lower-order frequencies of inflatable beams. Main, et al. wrote a very significant 1995 paper describing results of modal tests of inflated cantilever beams and the determination of effective material properties. Changes in material properties for different pressures were also discussed, and the beam model was used in a more complex structure. The paper demonstrated that conventional finite element analysis packages could be very useful in the analysis of complex inflatable structures. The purposes of this paper are to discuss the methodology for dynamically characterizing a large 5-meter thin film inflatable reflector, and to discuss the test arrangement and results. Nonlinear finite element modal results are compared to modal test data. The work is significant and of considerable interest to researchers because of 1) the large size of the structure, making it useful for scaling studies, and 2) application of commercially available finite element software for modeling pressurized thin-film structures.
Stags Example Problems Manual
This document summarizes the STructural Analysis of General Shells (STAGS) development effort, STAGS performance for selected demonstration problems, and STAGS application problems illustrating selected advanced features available in the STAGS Version 5.0. Each problem is discussed including selected background information and reference solutions when available. The modeling and solution approach for each problem is described and illustrated. Numerical results are presented and compared with reference solutions, test data, and/or results obtained from mesh refinement studies. These solutions provide an indication of the overall capabilities of the STAGS nonlinear finite element analysis tool and provide users with representative cases, including input files, to explore these capabilities that may then be tailored to other applications.
POST-FLIGHT TESTING AND ANALYSIS OF ZERO-G FOAM RIGIDIZED STRUTS
Strengthening inflated structures through rigidization of the enclosing membrane has been suggested as a way to improve robustness. Toward this end, rigid foam appears to hold signtjicant promise as a replacement ftir the pressurized gas of early inflatables. In March 1998, an experiment designed to manufacture foam rigidized struts was flown on the NASA KC-l 35 aircraft. This paper presents a description of the experiment and a comparison of properties offoam rigidizedstruts manufactured in the microgravity environment to those of struts manufactured in a I-G environment, The density proftle of the rigidizing foam and other morphological characteristics were not significantly affected by gravity in this experiment, This is due in part to the small struts required by the short duration of O-G in the NASA KC-135. Adhesion of the foam to the Kapton, however, was signtficantly d@et-ent in ., ”