ESDU Engineer

Flat Panels in Shear : The Strength Analysis Group is in the process of issuing a new Data Item (ESDU 02005) in the Structures Series.

Data Item No. 02005 is accompanied by ESDUpac A0205 which provides a Fortran computer program for the analysis of a flat, stiffened panel forming the web of a beam (such as an aircraft wing-spar) under a bending moment and shear load, the web having buckled under shear. The flanges (longitudinal members, assumed to be of angle section) and stiffeners (transverse members) may be on one side or both sides of the plate.

The program provides options to select one of seven riveted or bolted lipped or unlipped stiffener cross sections, each with or without a pad, or one of three integral cross sections.

The program offers two calculation procedures. One procedure yields the minimum reserve factors of the plate, stiffener and flange, the ratio of the nominal shear stress to the plate buckling stress, and the weight per unit length of up to 625 user-specified geometries. Alternatively, a detailed analysis of the strengths and buckling loads of the individual components of a single panel can be provided. The first procedure allows the relative performance of the designs to be compared and the user can specify up to 5 values for each of the plate thickness and of the stiffener pitch, height and thickness. In the second case, the program provides information on the plate strength remote from the edges and at the plate-to-flange joint, the buckling and forced crippling of the stiffeners, together with failure where research meets designthe stiffener attachments, the strength of the flanges and their attachments, and the post-buckled stiffness of the panel. The manufacturing eccentricity of the stiffener can be taken into account and the inelastic behaviour of the material of the plate and stiffener is handled by modelling the stress-strain curve following the methods in ESDU 76016.

The Item consists of two sections. Section 1 describes the application of the program and its theoretical basis. Section 2 of the Data Item may be considered as a Programs User’s Manual. It describes the use of the program, its input and output, and gives example calculations using the program.

The input data have a number of checks applied to them and the various error and warning messages that may then be generated are listed. The program is supplied as source code and in compiled executable form, and in a user-friendly form that prompts for input data on screen. All versions are available in the Series Software Volume, on the CD and in the internet version of the Series.

Neil Dev-Anand is the Senior Engineer responsible for the Structures Series. He can be contacted at ndev@esdu.com