Designettes: An Approach to Multidisciplinary Engineering Design Education

Design and other fundamental topics in engineering are often isolated to dedicated courses. An opportunity exists to foster a culture of engineering design and multidisciplinary problem solving throughout the curriculum. Designettes, charettelike design challenges, are rapid and creative learning tools that enable educators to integrate design learning in a single class, across courses, across terms, and across disciplines. When two or more courses join together in a designette, a multidisciplinary learning activity occurs; multiple subjects are integrated and applied to open-ended problems and grand challenges. This practice helps foster a culture of design, and enables the introduction of multidisciplinary design challenges. Studies at the Singapore University of Technology and Design (SUTD) demonstrate learning of engineering subject matter in a bio-inspired robotics designette (MechAnimal), an interactive musical circuit designette, and an automated milk delivery (AutoMilk) designette. Each challenge combines problem clarification, concept generation, and prototyping with subject content such as circuits, biology, thermodynamics, differential equations, or software with controls. From pre- and postsurveys of students, designettes are found to increase students' understanding of engineering concepts. From 321 third-semester students, designettes were found to increase students' perceptions of their ability to solve multidisciplinary problems

Target-driven sustainable product development

Figuring in sustainability in product development requires a profound understanding of the cause and effect of engineering decisions along the full spectrum of the product lifecycle and the triple bottomline of sustainability. Sustainability design targets can contribute to mitigating the complexity involved, by means of a formalised problem description. This article discusses how sustainability design targets can be defined and presents methods for systematically implementing these targets into the design process. To that end, different means of decision support mechanisms are presented. They comprise (a) use cases of target breakdowns in subsystems, (b) systematic reduction of solution space and (c) assistance in design activities to ensure achievement of sustainability design targets. This paper explains how interfaces to engineering tools such as Computer Aided Design/Engineering (CAD/CAE) or Product Data/Lifecycle Management (PDM/PLM) can be put in place to make the process of retrieving information and providing decision support more seamless

Developing green design guidelines: a formal method and case study

textThis thesis describes and demonstrates a method for consolidating, developing, and using green design guidelines for the innovation of greener products. Life cycle analysis (LCA) is one well-accepted tool for quantifying the environmental impacts of a product so designers can identify areas for redesign effort. However, LCA is a retrospective design tool that requires detailed design information that isn’t known until designs are near completion. Alternatively, green design guidelines provide proven techniques for designing greener products. They can be used during the early stages of design, when many decisions fundamental to innovation and environmental impact are made and before LCA is viable. This thesis extends the work already done in green design guidelines, by updating the current knowledge base and introducing a method for extending the set of existing guidelines to encompass new and emerging areas of sustainability. While guidelines have been created from prior experience in design for environment and life cycle analysis, they have not been maintained as a shared and coordinated repertoire of green design solutions. Instead, sets of guidelines are scattered throughout the literature, contain overlaps, operate at different levels of abstraction, and have varying levels of completeness. For example, some areas of green design guidelines, such as design for disassembly, are well established, while other areas of green design guidelines, such as minimizing energy consumption during use, are still being explored. Additionally, while numerous examples of green design guidelines exist, many of the guidelines have no documented validation of their life cycle impacts. The work for this thesis began with the compilation of a dynamic knowledge base of green design guidelines. This set of guidelines is a consolidation and updating of the green design guidelines already available in literature and can be used as a starting poinrt for future improvements and extensions as the field develops. A standard method was then proposed and tested for creating guidelines in currently undeveloped areas of green design, particularly energy consumption during the operation of a product. The method employs reverse engineering techniques and life cycle analysis to identify green requirements and develop corresponding, new green design guidelines. A case study of electric kettles demonstrated the usefulness of the method by yielding four new guidelines and four, corresponding, energy saving re-designs. For this example, the redesigns showed that guidelines can reduce energy consumption, but may incur tradeoffs with other life cycle stages. Calculation of tradeoffs revealed a range of net life cycle impact values that were caused by increased manufacturing demands and variability in consumer use habits. In addition to redesign in the kettle study, the four new guidelines were tested for usefulness in new product design by use of focus groups. Two groups were tasked with designing a new energy efficient toaster concept. Only one group was given the four green design guidelines that were uncovered using the proposed method. The design group using the new green design guidelines produced more viable and practical green features than the design group that did not have the guidelines as a design tool. These preliminary results suggest that the proposed method is useful for creating new guidelines that are beneficial to design teams tackling novel design problems that differ from the original case study. Further work is needed to establish the statistical significance of these results.Mechanical Engineerin

Probabilistic graphical modeling as a use stage inventory method for environmentally conscious design

textProbabilistic graphical models (PGMs) provide the capability of evaluating uncertainty and variability of product use in addition to correlating the results with aspects of the usage context. Although energy consumption during use can cause a majority of a product's environmental impact, common practice is to neglect operational variability in life cycle inventories (LCIs). Therefore, the relationship between a product's usage context and its environmental performance is rarely considered in design evaluations. This dissertation demonstrates a method for describing the usage context as a set of factors and representing the usage context through a PGM. The application to LCIs is demonstrated through the use of a lightweight vehicle design example. Although replacing steel vehicle parts with aluminum parts reduces the weight and can increase fuel economy, the energy invested in production of aluminum parts is much larger than that of steel parts. The tradeoff between energy investment and fuel savings is highly dependent upon the vehicle fuel economy and lifetime mileage. The demonstration PGM is constructed from relating factors such as driver behavior, alternative driving schedules, and residential density with local conditional probability distributions derived from publicly available data sources. Unique scenarios are then assembled from sets of conditions on these factors to provide insight for sources of variance. The vehicle example demonstrated that implementation of realistic usage scenarios via a PGM can provide a much higher fidelity investigation of energy savings during use and that distinct scenarios can have significantly different implications for the effectiveness of lightweight vehicle designs. Scenarios with large families, for example, yield high energy savings, especially if the vehicle is used for commuting or stop-and-go traffic conditions. Scenarios of small families and efficient driving schedules yield lower energy savings for lightweight vehicle designs.Mechanical Engineerin

Assessing Energy Requirements and Material Flows of Selective Laser Sintering of Nylon Parts

Selective laser sintering (SLS) is a prominent technology for rapid manufacturing (RM) of functional parts. SLS and competitive RM technologies are generally assumed to be more environmentally sustainable than conventional manufacturing methods because the additive process minimizes tooling, material waste, and chemical fluids. A thorough life cycle analysis (LCA) of the environmental impacts of SLS has yet to be published. This study focuses on a section of the SLS part life-cycle. It tracks the nylon powder material flows from the extraction and synthesis of the material to SLS part production. Basic material properties and environmental effects are reported. Estimates of material waste and energy use are also reported and compared with those of injection molding.Mechanical Engineerin

Material Waste of Commercial FDM Printers Under Realistic Conditions

Fused deposition modeling (FDM) is a prominent technology for additive manufacturing. Additive manufacturing is thought to minimize material waste, but the actual material waste could be larger than expected due to human or printer error. In FDM, the quantity of support material is influenced by the part orientation and other settings of the printing. Additionally, failures may result from insufficient preheating time, inappropriate geometry of parts, user error or printer malfunctions. Material waste from commercial FDM printers using ABS material in a heavily utilized open shop was collected in this study. The mass data of both support material and failed prints were recorded over time. In addition, the failed prints were classified into 9 different categories and weighed according to failure reasons. The data were analyzed and indicated that about 34% of the plastic used in the open studio was wasted. Only considering the failed prints as the extra amount of material consumed under realistic conditions, the mass of material lost to failed builds was about 2.22 times what might be estimated in a controlled process study. Suggestions to reduce the material waste for each failure type are given.Mechanical Engineerin

A Comparative Evaluation of Energy Consumption of Selective Laser Sintering and Injection Molding of Nylon Parts

Additive manufacturing is often advocated as a sustainable alternative to competing manufacturing technologies. This research study focuses on estimating and comparing the energy consumption required for different production volumes of nylon parts using either selective laser sintering (SLS) or injection molding (IM). For IM & SLS, energy consumption is estimated for nylon material refinement and part fabrication. For IM, energy consumption is also estimated for manufacturing the injection molds and refining their metal feedstock. A paintball gun handle serves as a representative part for calculating and normalizing material flows and processing times. For different sets of assumptions, cross-over production volumes are calculated, at which the per-part energy consumption of the two processes is equivalent. These energy-based cross-over production volumes are compared to similar economic cross-over production volumes available in the literature.Mechanical Engineerin