Computer Analysis of the F-111 Wing Assembly

A new computer program, developed by modifying and extending an existing space-frame analysis program (STAIR) is described. This program, designated MAST, is designed to analyze structures which are represented as assemblages of pin-ended bars and quadrilateral and triangular idealized membrane elements. The finite-element idealizations of the solution of three types of problems are described. These are (1) internal force analysis of stressed-skin structures; (2) stress analysis of plates and shells subjected to extensional and flexural deformations; and (3) stress analysis of structural components in three-dimensional stress states. Application of the technique is illustrated by describing the analyses performed on the F-111 wing and wing pivot assembly. These involved an internal load analysis of the entire wing assembly, followed by stress analyses of components of special interest within the pivot fitting. The results of the stress analyses are compared with those from a three-dimensional photo-elastic investigation and from full-scale model tests.