Surrogate Modeling of Stability Constraints for Optimization of Composite Structures

Problem of aircraft structural components (wing, fuselage, tail) optimization is considered. Solution of this problem is very computationally intensive, since it requires at each iteration a two-level process. First from previous iteration an update step at full component level must be performed in order to take into account internal loads and their sensitivities in the whole structure involved by changes in local geometry. Second numerous local analyzes are run on isolated elements (for example, super stiffeners) of structural components in order to calculate mechanical strength criteria and their sensitivities depending on current internal loads. An optimization step is then performed from combined global-local sensitivities. This bi-level global-local optimization process is then repeated until convergence of load distribution in the whole structure. Numerous calculations of mechanical strength criteria are necessary for local analyzes and results in great increase of the time between two iterations. In this work an effective method for speeding up the optimization process was elaborated. The method uses surrogate models of optimization constraints (mechanical strength criteria) and provides reduction of the structure optimization computational time from several days to a few hours.