Finite Element Analysis And Optimum Design Of Semi-Monocoque Airframe Str- Part I Finite Element Analysis

The prediction of the structural behavior of a practical fiber reinforced composite airframe structure presents a problem of extreme complexity. Extensive efforts have been expended over the years in the development of techniques to provide results of acceptable accuracy. Studies have been conducted to use the finite element methods for the analysis of composite airframe structures, and the results are brought into closer conformity with the test data. Based on the rather good results, a composite structural optimization program is aeveloped with stress and displacement constraint. Recent developments in two parts are addressed in two papers. Part one concerns the finite element analysis of composile airframe structures. A family of composite flange and membrane semi-monocoque elements are derived which are general adequate for determining the primary load path of most helicopter and aircraf t structures. Part two describes the Optimality Criterion Method and Sequential quadratic Programming Method to approach the stress-displacement constrained airframe design where composites are used in conjunction with metals.