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1. Understanding the Roles of Low-fidelity Prototypes in Engineering Design Activity

   Ali, Hadi; Lande, Micah (June 2019, ASEE Annual Conference proceedings)

   Practical ingenuity is demonstrated in engineering design through many ways. Students and practitioners alike create many iterations of prototypes in solving problems and design challenges. While focus is on the end product and/or the process employed along the way, this study combines these interests to better understand the product and process through the roles of initial prototyping through the creation of such things as alpha prototypes, conceptual mock-ups, and other rapid prototypes. We explore the purposes and affordances of these low-fidelity prototypes in engineering design activity through both synthesis of different perspectives from literature to compose an integrated framework to characterize prototypes that are developed as part of ideation in designing, as well as historic and student examples and case studies. Studying prototyping (activity) and prototypes (artifacts) is a way to studying design thinking and how students and practitioners learn and apply a problem solving process to their work. Prototyping can make readily evident and explicit (through act of creating and the creations themselves) some of the thinking and insights of the engineering designer into the design problem. Initial, low-fidelity prototypes are characterized as prototypes that are not always elaborate depictions containing all the fine details of the design. In fact, features in a prototype do not always appear in the final design. The underpinning of this work is that prototyping, as a process, is an act of externalizing design thinking, embodying it through physical objects. While several prescriptive frameworks have been developed to describe what prototypes prototype and the role of prototype, the role of low-fidelity prototypes, specifically, lacks sufficient attention. We will present prototyping rather as an holistic mindset that can be a means to approach problem solving in a more accessible manner. It can be helpful to apply this sort of mindset approach from these initial problem understanding through functional decomposition to quickly communicate and learn by trial and building in learning loops to oneself, with an engineering design team, and to potential stakeholders outside the team. 

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2. Bending Stability of Corrugated Tubes With Anisotropic Frustum Shells

   https://doi.org/10.1115/1.4053267  

   Wo, Zhongyuan; Filipov, Evgueni T. (April 2022, Journal of Applied Mechanics)

   Abstract Thin-walled corrugated tubes that have a bending multistability, such as the bendy straw, allow for variable orientations over the tube length. Compared to the long history of corrugated tubes in practical applications, the mechanics of the bending stability and how it is affected by the cross sections and other geometric parameters remain unknown. To explore the geometry-driven bending stabilities, we used several tools, including a reduced-order simulation package, a simplified linkage model, and physical prototypes. We found the bending stability of a circular two-unit corrugated tube is dependent on the longitudinal geometry and the stiffness of the crease lines that connect separate frusta. Thinner shells, steeper cones, and weaker creases are required to achieve bending bi-stability. We then explored how the bending stability changes as the cross section becomes elongated or distorted with concavity. We found the bending bi-stability is favored by deep and convex cross sections, while wider cross sections with a large concavity remain mono-stable. The different geometries influence the amounts of stretching and bending energy associated with bending the tube. The stretching energy has a bi-stable profile and can allow for a stable bent configuration, but it is counteracted by the bending energy which increases monotonically. The findings from this work can enable informed design of corrugated tube systems with desired bending stability behavior. 

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3. NOVICE DESIGNERS' USE OF PROTOTYPES AS COMMUNICATION TOOLS

   https://doi.org/10.1017/pds.2021.489  

   Krishnakumar, Sandeep; Lauff, Carlye; McComb, Christopher; Berdanier, Catherine; Menold, Jessica (August 2021, Proceedings of the Design Society)

   Abstract Prototypes are critical design artifacts, and recent studies have established the ability of prototypes to facilitate communication. However, prior work suggests that novice designers often fail to perceive prototypes as effective communication tools, and struggle to rationalize design decisions made during prototyping tasks. To understand the interactions between communication and prototypes, design pitches from 40 undergraduate engineering design teams were collected and qualitatively analysed. Our findings suggest that students used prototypes to explain and persuade, aligning with prior studies of design practitioners. The results also suggest that students tend to use prototypes to justify design decisions and adverse outcomes. Future work will seek to understand novice designers’ use of prototypes as communication tools in further depth. Ultimately, this work will inform the creation of pedagogical strategies to provide students with the skills needed to effectively communicate design solutions and intent. 

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4. OPTIMAL DESIGN FOR DEPLOYABLE STRUCTURES USING ORIGAMI TESSELLATIONS

   https://doi.org/10.1115/IMECE2019-11062  

   Cardona, Carolina; Tovar, Andres; Anwar, Sohel (November 2019, Proceedings of the ASME International Mechanical Engineering Congress and Exposition)

   This work presents innovative origami optimization methods for the design of unit cells for complex origami tessellations that can be utilized for the design of deployable structures. The design method used to create origami tiles utilizes the principles of discrete topology optimization for ground structures applied to origami crease patterns. The initial design space shows all possible creases and is given the desired input and output forces. Taking into account foldability constraints derived from Maekawa's and Kawasaki's theorems, the algorithm designates creases as active or passive. Geometric constraints are defined from the target 3D object. The periodic reproduction of this unit cell allows us to create tessellations that are used in the creation of deployable shelters. Design requirements for structurally sound tessellations are discussed and used to evaluate the effectiveness of our results. Future work includes the applications of unit cells and tessellation design for origami inspired mechanisms. Special focus will be given to self-deployable structures, including shelters for natural disasters. 

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5. Limits of Extramobile and Intramobile Motion of Cylindrical Developable Mechanisms

   https://doi.org/10.1115/1.4048833  

   Butler, Jared; Greenwood, Jacob; Howell, Larry L.; Magleby, Spencer (February 2021, Journal of Mechanisms and Robotics)

   null (Ed.)

   Abstract Mechanisms that can both deploy and provide motions to perform desired tasks offer a multifunctional advantage over traditional mechanisms. Developable mechanisms (DMs) are devices capable of conforming to a predetermined developable surface and deploying from that surface to achieve specific motions. This paper builds on the previously identified behaviors of extramobility and intramobility by introducing the terminology of extramobile and intramobile motions, which define the motion of developable mechanisms while interior and exterior to a developable surface. The limits of motion are identified using defined conditions. It is shown that the more difficult of these conditions to kinematically predict may be treated as a non-factor during the design of cylindrical developable mechanisms given certain assumptions. The impact of toggle positions for each case is discussed. Physical prototypes demonstrate the results. 

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