Non-Deterministic Optimization of Composite Structures Reliability

Abstract

A formal computational method is introduced to optimize composite structures for maximum reliability while accounting for uncertainties in fabrication, material properties, and loading. The approach is based on the combined use of probabilistic structural analysis, probabilistic composite mechanics, and a library of optimization algorithms. The effectiveness of the developed methodology is demonstrated by applying it to a composite simulated fuselage. With the use of optimization, the maximum displacement in the fuselage center is reduced by a factor of 4.5 while the reliability to preve nt ply failure is increased from 965/1,000 to 9 ,995/10,000. One end of the composite simulated fuselage is re -designed to include a grid system backed by a flat plate. The robustness of the optimized design is assessed using progressive damage analysis. The results show that, for the optimum design, damage initiation and burst pressures are respectively 2.5 and 1.3 times higher than those of the initial design.