Analysis of CFRP Flight Interface Brackets under Shock Loads

Abstract

Interface structures in spacecraft’s and flight vehicles encounter mechanical shocks from a variety of sources such as stage separation, release operations and sudden external disturbances. The flight interface brackets must be designed, analysed and tested to withstand these shock loads acting for short durations. Due to high strength-to-weight ratio and resistance to corrosion carbon fiber reinforced polymer (CFRP) is popularly adopted as flight interface brackets and are replacing metals. The response of CFRP flight interface brackets under shock loading is not fully understood. This paper presents transient shock analyses performed on typical flight interface brackets such as flat rectangular and L-shape CFRP brackets with fiber orientations in 33 different stacking sequences for fixed-fixed and cantilever boundary conditions;and subjected to impulse loading. Results indicated that the stacking sequence [90/0/0/90]s proved best for rectangular fixed and cantilever conditions while stacking sequence [90/90/90/90]s yielded best results for L-shaped cantilever and fixed-fixed boundary conditions with minimum reaction load at fixed end.