Free Vibration Analysis of Dual-Material-Inflated Torus with Acoustic-Structure Interaction

Abstract

With the expansion of satellite technology, there has been a simultaneous increase in the mass and size of the satellite. Thus, it seems an arduous task to launch the satellites with large and heavy accessories with current rocket technology. The inflatable structures are appealing with relevance to featherweight, high strength-to-mass ratio, minimal stow volume, and immense packing efficiency added with economical deployment cost. The toroidal shape is a crucial element in providing structural support to various imminent inflatable space structures encompassing large deployable communication antennas, solar thermal propulsion, and solar sail. In a unique study, the free vibration response of an inflatable torus made up two different materials of the same thickness (125 \(\upmu \)m), namely, Teflon (Elastic modulus, \(E=0.5\) GPa) and Kapton (\(E=2.5\) GPa) film have been investigated at varying pressure (3–9 kPa) by incorporating acoustic–structure interaction. The vision is to study the effect of pressure and, dual-material orientation (0\(^\circ \) and 6\(^\circ \)) on the change in resonant frequencies. It is noticed that with a hike in inflation pressure, the corresponding modes shift to higher frequencies, and the same trend is realized when using dual material but at translated higher frequencies. Also, the Modal Assurance Criterion (MAC) analysis is used to determine the similarity of mode shapes. This involves extracting the eigenvectors by post processing of the data obtained from finite-element simulations. On comparing, distinct eigenvectors corresponding to the modes are obtained. It is envisaged that the test template put together with numerical validation can pave the way for the rigorous design of inflatable torus structure.KeywordsInflated torusDual materialFree vibrationAcoustic-structure interactionModal assurance criterion