VIBRATION CONTROL OF INFLATABLE TORUS

Abstract

Inflatable structures become very popular due to its vast application in the engineering as well as structural field. These structures are light weighted and posses high strength (compared to strength to mass ratio).These qualities make it a perfect structural member in space Antenna field. The pay off load send in the space by any space agency is limited due to high cost of the launch vehicles and limited space availability. Here inflatable structures come into picture due to light weight and minimum stowage capacity these structures can be easily transported from one location to another in minimum cost. The design issues in the field of satellite antenna are its limitation of the size of pay off load and the space availability during the time of launching. For the reduction of size and mass of launch vehicle, gossamer structures or popularly known as inflatable structures are very useful. The only key issue is its susceptibility against vibration disturbances because it has poor damping capacity and low stiffness. This dissertation explains the dynamic dynamics of inflatable torus and its vibration control with the help of piezoelectric actuators. Further a experimental approach is also explained to control the vibration of toroidal structures. The torus is modeled with the help of finite element model. A commercial finite element software package ABAQUSTM is used to model the torus because it is very tedious job to model the torus analytically. The equation of motion for both inflatable structures and piezoelectric materials are explained. The torus natural frequencies and mode shapes are calculated. In the analysis it is observed that the internal pressure and aspect ratio of the torus play significant role. When aspect ratio is small the torus behaves like a ring but when it is increased the mode shapes changes