TOPOLOGICAL, GEOMETRICAL AND STRUCTURAL OPTIMIZATION OF COMPLEX MECHANICAL SYSTEMS

Modern 3D CAD permanently modifies the development process of most industrial products. The traditional approach, in which it was necessary to design the components in short time to build the prototype in order to make assembly/functional/structural/durability tests, is no more necessary even for complex systems. The old “lean thinking” approach based on the “brain storming” is not so far applicable on the complex systems in which it is impossible to estimate the best solution without an extensive design process. In the old days, it was said that the 90% of the exceeding costs on product development were determined during the first 10% of the project. All these old ways of thinking are typical of an anachronistic vision of the design project approach. In facts, nowadays, due to the possibility of virtual testing, the design has to be optimized by the CAD/CAM/CAE methods, then in its final phase it has to be experimentally tested and produced.The production methods have to deal with the innovative techniques of rapid prototyping, in order to reduce the time-to-market. In this paper the design of an aeronautical engine is introduced, starting from a commercial- well tested motorcycle engine, with an optimal weight to power ratio, and a well known reliability. The transformation from motorcycle to aircraft has lead to an initial digital mock up of about 65 kg with 126 parts. Ulterior refinements of the project have brought to 6 new configurations, up to the best one of only 40 kg and 92 parts. The one-year-long optimization process has brought to the production of a simpler prototype with a reduction of development of 30% from the first digital mock-up. The year spent in the modelling and the optimization of the project has been fully rewarded by the huge savings.