Numerical and experimental fatigue life estimation of airplane emergency door bracket in various mission profiles

In this paper, fatigue analysis and life estimation in the bracket of an airplane emergency exit door was investigated. The design and static analysis of door has already been carried out. The critical parts of door structure were selected based on static stress analysis and principal structural elements criteria. The bracket is one of 4 critical parts of door, selected due to those criteria. The stress spectrum on the bracket was obtained from airplane flight profiles and the loads of door existing in the flight envelope. By using the rain flow cycle counting algorithm, the fatigue life of bracket has been calculated. Two codes were developed by using Matlab software. One code was obtained the stress spectrum in a flight block and another code was count the stress cycle based on the rain flow method. The results were shown that bracket was safe at flight envelope. Finally, some fatigue tests has been carried out on the bracket and good agreement was found in the results evaluated numerically and that obtained experimentally.