Towards the definition of an engineering method to support the design for assembly and installation of aircraft systems at the conceptual design stage

Abstract

The design of new products requires a complex set of activities which need to be carried out in a systematic manner. In the past years, great focus has been put on optimizing the process in terms of cost, time, and quality. Several tools and methods have been developed to support designers and engineers during the whole product development process. Moreover, it is well-know that optimizing products during early design phases lead to a cost reduction of around 70% of the overall product cost. Nowadays, a great number of methodologies are available in the literature to optimize the design of products. Among all, Design for Manufacturing and Assembly methodologies aim at optimizing the product manufacturing and assembly phase, which can impact up to 40% of the overall product cost. For complex engineering systems, such as aircraft and aerospace equipment, this influence is even more significant. To date, the design of aerospace civil products is consolidated, and the optimization process is required to meet market demands. The design of these products is tackled from a system engineering point of view, assuming the aircraft product architecture is already given. This approach limits the potential benefits that can be introduced by developing novel methods at the conceptual design phase. The aim of this research work is to provide a method, called Conceptual Design for Assembly, to assess the assembly and installation of complex systems into a product and to provide redesign guidelines to help designers and engineers reduce its complexity. The approach is based on a specific framework that allows for the gathering of product architecture data. Then, using a mathematical model, assembly indexes are derived. The approach also allows for the collection of technical information from the production and assembly departments using structured tables, facilitating the transition from implicit to explicit knowledge. The method is applicable at early design phases, such as the Conceptual Design phase. The CDfA identifies major issues in the system under investigation and provides a practical tool for implementing redesign actions in structured steps. Starting from the functional analysis of the product, the method guides the user through the definition of the mathematical model to assess the product architecture of the system analysed. Once the assessment is completed, it is possible to obtain design guidelines to improve the product architecture. The Conceptual Design for Assembly method was tested on two real industrial case studies: the Nose-Fuselage and the Cabin systems of a commercial aircraft. Results showed that improvements were obtained for both architectures applying redesign guidelines. Finally, a software mock-up that can be coupled to an existing CAD program is proposed. The software seeks to make the approach more suitable to be adopted in daily engineering practices avoiding time-consuming and prone to error activities. The developed method and the integrated platform enable designers and engineers to evaluate and improve the installation of complex systems into a product architecture, reducing the intrinsic uncertainty of early design phases. The Conceptual Design for Assembly method can be extended to investigate the product architecture of complex products in other industrial fields.