Method of optimizing stiffened panels under stress
AssigneeAirbus France
InventorsCeline Gallet, Eric Buchet, Michel Salaun
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Abstract
The subject of the disclosed embodiments is a method of optimizing stiffened panels under stress. In particular, the method makes it possible to determine the stress distribution in stiffened panels with postbuckling taken into account. The method proposed is a coupling between an overall, linear stress calculation approach, based on strength-of-materials results, and a local, nonlinear approach for the behavior of the stiffened panel. The disclosed embodiments fall within the field of aeronautical design, at the pilot study stage in the definition of a civil transport airplane of conventional architecture.
Claims11
Method of optimizing the design of stiffened panels intended for the fuselage of an aircraft (5) under load, said fuselage being divided up into a set of rings (1), each ring being decomposed into subsystems (2), each subsystem being composed of a stiffener (3) and a skin portion (4) to which said stiffener is fastened, said subsystem (2) being subjected to a combined loading of compression and shear stress, characterized in that said method comprises the following successive steps:
- a) the local characteristics of the ith subsystem in the initial state, corresponding to a state with no buckling, are determined;
- b) the initial overall characteristics of the ring are determined, namely the initial offset of its neutral bending axis ΔZ0, its static moment [EW]0 and its flexural rigidity [EI]0 are determined from the local characteristics of the ith subsystem;
- c) the following are determined in an iterative loop and each iteration n:
- the working local characteristics of the subsystem taking into account the loss of rigidity due to buckling, and
- the new overall characteristics of the ring, namely its offset [ΔZ0]n, its flexural rigidity [EI]n and its static moment [EW]n, the convergence of the iterative loop being obtained if the new offset is below a threshold;
- d) the final stress distribution in the subsystem is determined;
- e) the safety margins are determined from the final stress distribution in the subsystem taking postbuckling into account;
- and
- f) the mass function of the subsystem is minimized while respecting the safety margins.
Dependencies are inferred from the claim text.