Abstract: A novel multidisciplinary collaborative optimization method – Design space decrease collaborative optimization (DSDCO) is presented. According to the subsystem-level optimization results, the equations of planes used to decompose design space are determined. Then, the current design space is divided into several subspaces reasonably. Some infeasible design subspaces are deleted and the rests are passed to the system-level optimization as the elements of the system-level variables space. The system-level optimization value in each subspace is analyzed, then the preferred system-level optimization results and the next iteration design space are chosen. The iteration process is continued until the system-level optimization solution is converged. In DSDCO, as the design space is updated, the system-level optimized mathematical function is corrected. The system-level nonlinear equality constraints in conventional collaborative optimization(CO) are turned into linear inequality constraints, i.e. variable boundaries, so the computation difficult problem in the conventional CO is avoided. For MDO problem with variable boundaries, DSDCO has no limit to the start point and constraint function convexity. Three typical examples of a numerical test problem, a gear reducer design problem and a spring design problem illustrate the capabilities of the DSDCO method.

Key words: collaborative optimization(CO), design space, multidisciplinary design optimization(MDO), nonlinear constraint