Robust design is defined as a systematic approach to finding optimum values of design factors which result in economical designs with low variability. Many Japanese and U.S. companies strive to achieve robust design through the use of Statistical Process Control (SPC) and Six Sigma approaches. However, these methods are usually applied to address manufacturing variability in the later stages of the design process, when as much as 70-80% of the LCC has already been committed through earlier design decisions. These early design decisions have been predominantly product performance based and passed on to subcontractors, suppliers, and vendors for implementation. It is during the early stages, i.e. conceptual/preliminary or system design, where technology uncertainty and design freedom are the greatest, and it is when life cycle affordability must be addressed. All of theses processes involve a relationship between time and cost.Theoretical Cost/Time Analysis (CTA) curves will be developed from Process Based Cost (PBC) models for the critical aeronautical system process of certification. CTA will also be included in a system level Aircraft Life Cycle Cost Analysis (ALCCA) for cost-performance trades using Robust Design Simulation (RDS) in a Mutidisciplinary Design Optimization/Systems Analysis (MDO/SA).
Potential Commercial Applications:Activity Based Costing (ABC) methods are being developed for re-engineering business processes in many industries. For selection of new technologies in the aircraft design process, PBC methods can be used to address downstream processes, such as certification cost/time considerations. An ALCCA using Robust Design Simulation (RDS) and PBC models can provide a set of PC-based software tools for rapid evaluation of new processes, including development, manufacturing, certification and support.
