An enhanced multiobjective formulation technique for multidisciplinary design optimization

An enhanced multiobjective formulation technique, which allows specific objective functions to be emphasized during the optimization process, has been developed and demonstrated on a high speed aircraft design application. The Kreisselmeier-Steinhauser (K-S) function approach, which has been used successfully in a variety of multiobjective optimization problems, has been modified using weight factors which enables the designer to impose increased emphasis on specific objectives during the design optimization process. The developed technique has been applied to two problems. The first is a classical three bar truss problem, and the second is a high-speed aircraft application in which the multiobjective optimization procedure simultaneously minimizes the sonic boom and the drag-to-lift ratio (C_D/C_L) of the aircraft while maintaining the lift coefficient within prescribed limits. The flow equations are solved using a threedimensional parabolized Navier-Stokes solver. Sonic boom analysis is performed using an extrapolation procedure. The aircraft configuration is that of a doubly swept wingbody. The results are compared with those resulting from an equally weighted K-S multiobjective optimization. Results show improvements from the equally weighted optimization in both problems.