Finite Element Analysis of a Composite Bulkhead Structure

Abstract

Reducing structural weight is one of the major ways to improve aircraft performance. Lighter and/or stronger materials allow greater range and speed and may also contribute to reducing operational costs. Nowadays composite materials are widely used in “primary” structural components such as fuselage, for which contrasting requirements like lightness and structural strength are required, so particular attention is necessary during its design. In this paper a composite front bulkhead, subjected to ultimate pressure load, was examined. The front bulkhead is made of a composite skin, stiffened with seven vertical stiffeners linked through metallic fittings; the whole system is joined to the fuselage by rivets. A Finite Element model was established: the used elements were four nodes shells, simulating composite layers, and two nodes bar elements, simulating rivets; the structure was clamped and a pressure load was applied to the skin. A linear static stress analysis was performed to calculate strains in particular points in which strain gauges or rosettes are placed: the numerical results, compared with experimental ones, show a good degree of correlation. Stress calculations were performed in order to verify the front and rear bulkhead structural safety.