This paper on "Efficient Finite Element Modelling of Buckling and Post-Buckling Behaviour of Flat Stiffened Panels" was presented at the NAFEMS World Congress on The Evolution of Product Simulation From Established Methods to Virtual Testing & Prototyping - 24-28 April 2001, The Grand Hotel, Lake Como, Italy.

Abstract

Fuselage panels are commonly fabricated as skin-stringer constructions, which are permitted to locally buckle under normal flight loads. The buckling and post-buckling analysis of these structures is presently based on empirical and semi-empirical data. These methods are therefore conservative and hence can result in over designed structures. In related work a Finite Element methodology for the analysis of flat, riveted stiffened panels loaded in compression has recently been developed, which has the potential to eliminate analysis conservatism. The drawback with this modelling methodology is the time and cost required to build and run these models.
This paper reports on the development of a modelling strategy to reduce the computational effort required to perform non-linear Finite Element analysis on large fuselage panels. The non-linear pre and post buckling stiffness of the structure is represented by simple spring and beam elements. Each element encapsulates both geometric and material non-linearity for one translational degree of freedom of the collapsing panel.
A number of approaches were examined to create the 1D element properties using results from detailed 3D Shell models, theoretical analysis, and mechanical tests. Results from the Finite Element analyses were compared to experimental data and correlation between idealised elements and the test data was good. These results have been very promising, significantly reducing the analysis time with no associated penalty in accuracy. The idealisation method has potential for application to complex non-linear problems, as exemplified here by buckling, in large analysis models allowing for the rapid evaluation of critical regions and loads early in the design programme.