PhD Defence at DTU Mechanical Engineering

PhD Defence 19th October: "Design for Micro Manufacturing"

Monday 21 Sep 15

Farzaneh Omidvarnia from DTU Mechanical Engineering defends her PhD, "Design for Micro Manufacturing", Monday 19th October. The defence takes place at 13.00 in Building 306, auditorium 38, DTU Lyngby. 

The number of products benefiting from micro components in the market is increasing, and consequently the demand for well-matched tools, equipment and systems with micro features is eventually increasing as well. During the design process of micro products a number of issues appear which are inherent mainly due to the size effect in the micro range but negligible in the macro scale. In fact, some aspects in design for micro manufacturing are considerably different compared to the design procedure taken at the macro level. Identifying the differences between design considerations at micro compared to macro scale, and defining potential guidelines based on them, provides an opportunity to modify the conventional design methodologies towards becoming micro specific. In the present thesis, the design process of micro products is investigated through using different design methodologies.

The application of design for x (DFX) principles in the micro domain is studied by focusing on design for manufacturing (DFM) and design for assembly (DFA) in redesign of two micro products, a micro on-off switch and a micro optical unit. “Integration” is proposed as a potential solution for designing towards design for micro manufacturing and assembly (DFμMA) principles which results in feasibility and manufacturability of the products. Since there is a linkage between design and manufacturing in micro scale, development of DFMA rules for micro manufacturing is suggested. In addition, the environmental effect of micro manufacturing compared to macro manufacturing is considered by performing life cycle assessment (LCA) of some micro components and their macro counterparts. This is done as a step towards design for life cycle (DFLC) for micro manufacturing. The result of this study revealed the fact that the hazardous environmental impact of micro manufacturing is even more than macro manufacturing, and this is due to the large amount of waste out of micro manufacturing compared to the conventional macro manufacturing.

As one of the main case studies in this research work, the design process of a micro direct methanol fuel cell (μDMFC) is investigated by taking the manufacturability into account. Several designs for an orientation free μDMFC are proposed and the feasibility of realizing the proposed designs is discussed based on manufacturing constraints and functional criteria. Furthermore, biomimetics, as a potential design approach to be used in the micro domain, is applied to develop solutions for the μDMFC. Two biological phenomena, which are similar to the required function in μDMFC, are identified and imitated in finding the solution for orientation dependency and fuel delivery in the fuel chamber. The proposed designs are evaluated and the selected one, considering the design criteria and manufacturing limitations, is analyzed in COMSOL software. Additionally, an initial test is performed to observe the basic performance of the proposed design.

The conclusion of the mentioned investigations on design for micro products in this research work, also the results obtained from step by step development of a micro heat exchanger (as another case study), is formulated into a micro-specific design methodology. For this purpose, primary design ideas are suggested for a micro fluidic heat exchanger based on the conventional macro heat transfer principles. Then by taking micro design considerations into account, secondary design ideas are proposed. Thermal performance of the design ideas is analyzed using COMSOL software and the designs are evaluated based on the design criteria, i.e. manufacturability and functional performance. The final design is obtained through several design iterations and optimization. The feedbacks and lessons learned through different design iterations are collected in a unit called “RTC” (rules to consider) to be used in design of similar micro fluidic heat exchangers.

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21 OCTOBER 2020