What MDO really does MSDO Framework MDO mathematically traces a path in the design space Design Vector Simulation Model Objective Vector from some initial design x towards improved designs 「1 Discipline A Discipline B (with respect to the objective J). J. It does this by operating on a large number of variables Discipline C and functions simultaneously-a feat beyond the power of the human mind. Coupling Multiobjective Optimization Approximation The path is not biased by intuition or experience. Optimization Algorithms Methods This path instead of being invisible inside a "black box" Numerical Techniques Sensitivity Tradespace (direct and penalty methods) becomes more visible by various MDO techniques such Analysis Exploration as sensitivity analysis and visualization Heuristic Techniques Coupling (DOE) (SA,GA) Isoperfommance Optimization does not remove the designer from Output Evaluation the loop,but it helps conduct trade studies Massachusetts Institute af Technology-Prof de Weck and Prot Wicox System Engineering by J.J.Gao CLCO 国 25 System Engineering by J.J.Gao ③cLGo 国 26 Simulation versus Optimization Typical Process in MDO (1) Define overall system requirements There are two distinct components of the MSDO (2) Define design vector x.objective J and constraints process: (3) System decomposition into modules The optimization algorithm decides how to move (4) Modeling of physics via governing equations at the module level-module execution in isolation through the design space. (5) Model integration into an overall system simulation The simulation model evaluates designs chosen by the (6) Benchmarking of model with respect to a known optimizer.Both objective functions and constraints must system from past experience,if available be evaluated. (7) Design space exploration(DoE)to find sensitive and important design variables x, Sometimes,disciplinary simulation models can be used (8) Formal optimization to find min J(x) in an optimization framework,but often they are not (9) Post-optimality analysis to explore sensitivity and appropriate. tradeoffs:sensitivity analysis,approximation methods,isoperformance,include uncertainty System Engineering by J.J.Gao ③ctGe 27 System Engineering by Gao ③c1G0 28+ - System Engineering by J. J. Gao 25 What MDO really does + - System Engineering by J. J. Gao 26 MSDO Framework + - System Engineering by J. J. Gao 27 Simulation versus Optimization + - System Engineering by J. J. Gao 28 Typical Process in MDO