To determine the effect of thermal shock On a fixed glass dome

Abstract

An infrared (IR) homing of an aircraft is an enclosure that protects the infrared (IR) seeker, enhances the aerodynamic ability of the dome and decreases the resistance in flying. It also protects IR seeker which is important for cueing of targets and tracking of the final approach. High speed aircrafts mostly consist of glass domes in the front that are clamped or bonded inside a metallic housing. A sudden short duration of high speed during a chase is encountered in which the bonded dome has to bear the pressure and a frictional rise in temperature on the outer surface whereas the inner surface will not be able to reach the same temperature. This sudden rise in temperature and the resultant uneven temperature distribution on the outer and inner surface along with the air pressure creates stresses in the dome mostly due to thermal shock and difference in coefficients of thermal expansions of the metal and glass. Thus, the material of the dome must have good mechanical properties to withstand thermal shock. In this thesis, a thermal-structural coupled analysis of the dome has been performed based on two materials i-e BK7 and spinel. The temperature and pressure loads derived from the fluent have been forced on to the surface of the dome which yields maximum stress (σ), maximum deformation and thermal shock on the dome. The results are analyzed to find the Survivability of the dome