Mahesh Tampi and Christopher Jenkins on Local Membrane Vibrations and Inflatable Space Structures

April 21, 2012 - PRLog -- Conference Proceeding Paper-Part of:    Space 2000

Abstract: The study of vibrating membranes goes back at least 3 centuries. Motivations for such studies were the solution of practical problems; a rich example is the investigation of acoustics of musical instruments such as drums and bells. In modern times, membranes have provided a canonical formalism for mathematical analysis, due to their vanishing thinness and resultant absence of any bending rigidity. Moreover, numerous practical applications exist for membrane structures, and are in fact growing in importance.

Examples are architectural and civil structures, diaphragms in switches and transducers, biomedical prosthesis such as artificial arteries and organs, and space-based applications such as radio antennas and optical reflectors. Dozens of theoretical studies exist in the literature with regard to membrane vibrations. These cover linear and nonlinear models, various shapes and boundary configurations, and numerous analysis methods including closed-form, asymptotic expansions, and numerical methods (FEM, BEM, etc.).

Such studies are ongoing and of current interest. However, probably less than one dozen experimental studies can be found in the open literature. Even the simplest classical cases have not been thoroughly investigated. This is due at least in part to the extreme flexibility and lightness of membranes and the noncontact measurement methods thus implicated. What data that does exist is significantly limited, inaccessible, and insufficient for use in validating theoretical results.

Local vibrations are not explored at all. Moreover, answers to pressing questions in modern applications need to be addressed. Interesting and important problems currently exist such as: How do effects like wrinkling, thermal loading, and manufacturing variables affect the vibrational response of membrane/inflatable space structures? Can adaptive control methods use vibration information for local and global state estimates in such structures In this presentation, we first provide some background on shape control of precision membrane/inflatables, including applications, solution methods, and results. Then we present some new experimental results for the vibrating circular membrane, generated with a non-contact scanning laser vibrometer. Finally, we provide some comments on use of local membrane vibrations for shape control purposes.

For more info:
http://cedb.asce.org/cgi/WWWdisplay.cgi?120385