Abstract: The numerical drawbacks of standard collaborative optimization strategy (CO) and their reasons are pointed out. As to resolve the computationally difficulty caused by breaking Kuhn-Tucker condition in system level optimization, an enhanced collaborative optimization strategy with feasible direction sequential unconstrained minimization technology (FD-SUMT) exterior method (ECO-FSM) is proposed. FD-SUMT exterior method independent of Lagrange multiplier is employed in system level optimization, which restricts the system level design variables in their feasible region and eliminates the singularity phenomenon resulted from the boundaries violation of design variables in traditional SUMT exterior method. The penalty factor is updated in terms of the dynamical inconsistence information among different disciplines to accelerate the inter-disciplinary coordination. Several test problems are used to validate the performance of ECO-FSM, moreover, comparative study with other enhance CO is also carried out. Study results reveal that boundaries violation of design variables in system level optimization is eliminatedisFD-SUMTirection during ECO-FSM optimization process, and convergence performance, numerical robustness and convergence speed are evidently upgraded as well. Eventually, ECO-FSM is verified to be practical for engineering problems through a conceptual optimization design of subsonic jet transport using ECO-FSM.

Key words: Collaborative optimization strategy, Feasible direction SUMT exterior method, Multidisciplinary design optimization