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Aircraft designers are faced with a process that requires too many resources to encompass all requirements, design options, and tools. To find a set of feasible, not necessary optimal, solutions a human uses feasilization; integrating heuristics of problem simplification, problem decomposition, and trial and error methods. This paper focuses on problem decomposition, discussing implementation and usefulness. Problem decomposition yields a tree of product design problems. The tree structure offers a straightforward interface for inspecting the design specification and addition of new engineering knowledge. Using the product design process commonality, every problem can be solved using the same framework. The methodology is tested in a conceptual design study of a wing-type product, based on structural design considerations.

The Multi-Disciplinary Design Optimisation (MDO) process of products can be supported by automation of analysis and optimisation steps. The Design and Engineering Engine (DEE) is a useful concept to structure this automation. Within the DEE, a product is parametrically defined using Knowledge Based Engineering (KBE) techniques. The analysis of a particular product instantiation of this product model is performed by discipline analysis tools and a search engine provides a strategy to drive the design toward a feasible design, satisfy functional and performance requirements and constraints. To power the automatic analysis in this MDO setting an Agent Based Framework (ABF) has been developed. From the first release agent implementation several positive and negative aspect were found and addressed. It appeared that the framework requirements from literature often have a holistic approach, striving for integration of the MDO problem on the desktop of the engineer, rather than make use of distributed design capabilities in teams of engineers. In this perspective four levels of scoping are identified; organisational scoping level, framework or integration level, tool or engineering service level and data scoping level. These four scoping levels are a good frame of reference to link the identified actors, the four main established functions of a framework and the recent contributions in engineering framework development. Moreover the four levels of scoping helped to show not only the existence of product and process knowledge but also pointed out that there is a need to glue these independent knowledge areas together by using problem knowledge. Whit this problem knowledge, in form of a problem definition language, it should be possible to dictate the behaviour of the MDO framework. Conclusively, the second release agent software is described and various industrial use cases and accompanying network architectures are described for which the framework software will be made compatible with. Finally a status update to the implementation is provided.

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In this paper a fuselage shell, made of fibers composite material, of a passenger aircraft is optimized to get a minimum weight. Two different structural configurations of foam-filled sandwich and stiffened shells are analyzed under the dynamic loads due to the gust. A knowledge based engineering (KBE) approach is formulized to automate the multidisciplinary optimization problem in three different layers. The first layer takes care of the optimization of full fuselage under the constraints of real and negative eigenvalues to get an asymptotically stable closed-loop system. The second layer and third layers, take care of the optimization of the several sections along the length of the fuselage and the optimization of a particular panel of a section, respectively. The constraints in the second and third layers include the critical buckling and wrinkling stresses of the panels and the sections, under bending and torsion loads. The design variables are the stacking sequence of fibers orientations, sizes and positions of the stiffeners in a panel, section length along the longitudinal axis of the fuselage, and the skin thicknesses of the panels. Finally both of the optimized designs are compared with each other in terms of minimum weight, stability and moreover in terms of manufacturing.