Riassunto analitico
Over the years, the industrial product design process has undergone continuous changes and development. Advanced and innovative methodologies for product design optimization had to be developed by engineers to improve product quality, lowering production costs and accelerating time-to-market, allowing them to compete in the global market. The main reasons for the development of these methodologies were the rising competition, multitude of standards and regulations, and constrained profit margins. In this environment, Concurrent Engineering approaches (also known as simultaneous engineering) are crucial, particularly in important industries, like the automotive.
Nowadays, vehicles consist of a huge number of components compared to the vehicles that were built in the past, with various materials, functions, and manufacturing techniques. Therefore, the management of assemblability and cost of these parts is extremely complex and includes all stages of the product lifecycle beginning with the product design. Consequently, it is crucial to control the geometrical and dimensional deviations to comply with product and process demands. Practices for geometrical specification and tolerance analysis of industrial products, known under the term of Dimensional Management (DM), supported by the application of international standards as ASME-GD&T and ISO-GPS are increasingly frequent. With the aid of Computer-Aided Tolerancing (CAT) tools, the impact of the tolerances on products can be taken into account early on during the design process using the so-called Design for Tolerancing (DfT) approach. Tolerance design is a challenging and complex task, whose optimal utilization in the industrial field is hampered by numerous factors making it difficult to implement standards and tools on actual products. Furthermore, Computer-Aided Tolerancing (CAT) tools address how tolerances affect product functionality and assembly requirements.
Over the last decades, due to the aforementioned issues, the activity of tolerancing has undergone constant evolution aiming at an optimum tolerance design. As a result, various design strategies and methodologies have been introduced. The key element for the improvement of tolerance design is to define a systematic approach capable to exploit the benefits of the concurrent utilization of engineering software, improving the capabilities of Computer-Aided tools and the practices of Model-Based Definition (MBD). Consequently, to take advantage of the capabilities of advanced and integrated simulations, the development of a design methodology is required.
The aim of the present thesis is the definition and development of an appropriate methodology for GD&T allocation and tolerance stack-up analysis of automotive components. The development of the methodology is based on the implementation of predictive models, application of Dimensional Management (DM) approach and integration of Design for Tolerancing (DfT) approach. The main focus of this thesis is the improvement of automotive components design, taking into consideration the effects of geometrical and dimensional variations of the components on functional requirements and assemblability at the early phases of the product development process. An approach for computer-aided tolerance specification and analysis is defined, aiding to the development of a modelling methodology for Computer-Aided Tolerancing simulations. The integration of Computer-Aided tools and theoretical approaches enables the analysis of tolerance effects on the performance, quality and assemblability. Finally, this methodology is applied on a high-performance V6 engine providing certain results.
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