Fail-Safe Design Analysis of an Aircraft Fuselage with Crack Stopper Strap

Abstract

This paper reveals one of the design philosophies, fail-safe is used to arrest the crack propagation of airframe. The two important cracks considered for the design of pressurized fuselage are circumferential and longitudinal. The fuselage cabin pressurization and depressurization cycle create a fatigue load on the airplane structure and produce cracks where the tensile stress is maximum on the structural components. If the crack propagation is not controlled, they propagate during the flight and eventually land on the complete loss of the airplane structure. The design feature introduced into the airframe bulkheads to stop the crack propagation during the flight is crack tear straps. The approach utilizes a finite element modeling and analysis to assess the damage in the bulkheads and stringers with crack stopper straps and without crack stoppers. The design and analysis tools used in the in this work are Catia V5 and ANSYS. The analysis is carried out under fixed support conditions of the fuselage structure at the maximum design load conditions. The fatigue life of the stiffened panel with tear strap is more than the panel without tear strap. The deformation under cyclic loads for the panel with strap is less than the fuselage stiffened panel without crack strap