Analysis of Fatigue Cracks in Frame 360 Section 41 of B747

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Mashayekhi, Rouhollah | 2014

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Type of Document: M.Sc. Thesis
Language: Farsi
Document No: 46295 (45)
University: Sharif University of Technology
Department: Aerospace Engineering
Advisor(s): Adibnazari, Saeid
Abstract:
In this project, the structure of an aircraft and its sensitive areas has been studied for fatigue damages and then the design philosophies have been analyzed. Subsequently, relevant analysis and calculations have been conducted on a critically important part of the airframe (due to its location), which has suffered fatigue due to the age of the aircraft. This part belongs to the airframe of a Boeing 747, known as frame 360 in section 41 of the body of the aircraft, in which the numerous flight cycles have led to the creation and propagation of fatigue crack.
In the first stage of this project, the remaining life time of the frame has been estimated using theoretical relationships. In the second stage, cracks observed on the frame have been modeled using a software called Abaqus, and then the stress intensity factor and the remaining fatigue life of this frame have been estimated for two different scenarios, firstly, the frame, as is, and without any repair or modifications; and secondly, with a reinforcement plate attached on the frame. Finally, the results of the two scenarios have been compared a recommendation for increase in the life of the airframe has been made.
Keywords:
Fatigue Crack ; Crack Growth ; Safelife ; Fatigue Life ; Damage Tolerance ; Boeing 747 Aircraft

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