Hind D. Derar

Date of Award

2008

Level of Access Assigned by Author

Campus-Only Thesis

Degree Name

Master of Science (MS)

Department

Mechanical Engineering

Advisor

Vincent Caccese

Second Committee Member

Mohen Shahinpoor

Third Committee Member

Senthil Vel

Abstract

At the end of Space Shuttle mission, it re-enters the earth's atmosphere with a speed that exceeds 17000 mph, slowing down to landing speed causes friction that results in external surface high temperatures, as high as 3000 °F which is above the melting point of steel. While in Orbit, the orbiter airframe and major systems are exposed to external temperature fluctuations between the day and night phase from -200 °F to +200 °F during each 90-minute orbit. Therefore, to protect the Orbiter, its occupants, its airframe and major systems from the temperature extremes, special thermal shields were invented known as the Thermal Protection System (TPS) to withstand stresses and vibrations that are experienced during launch as well as thermally induced stresses imposed during temperature changes. Adding these thermal tiles to the structure changes its material properties since they are an addition to the mass. Modes are dependent on the material properties such as mass, stiffness and damping properties also determined by the boundary conditions of the structure. Any change in either the material properties or the boundary conditions will change the modes causing the structure to vibrate differently. This study is intended to further develop methodologies that can accurately measure, monitor and predict the condition of the Thermal Protection System (TPS) of primary and secondary structural components of the Space Shuttle. In addition, investigate the structural and non-structural systems as the non-structural mass can affect the evaluation of vibration structure. The research is performed using a combination of experimental methods that consist of physical impact tests, analytical methods, monitoring techniques and data analysis techniques.

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