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Renato Picelli, Scott Townsend, H. Alicia Kim
J. Mech. Des. Nov 2020, 142(11): 111705 https://doi.org/10.1115/1.4047152 The shape optimization of microstructural cells is investigated in this paper. Microstructure optimization yields the design of an architected material with a desired material property. Material usage and cost can be reduced by inserting holes into the microstructure. However, depending on the hole shape, the macroscale structure can fail because of the mechanical stress observed in the microstructural cell. This work investigates the possible stresses present in a microstructure and explores how shape optimization can be used for obtaining improved (optimal or nearly-optimal) cell configurations that have lower mechanical stress. The mechanical (von Mises) stress is evaluated using the finite element method. Cell shape optimization using mathematical programming is achieved using the level set method. As a result of this study, engineers have greater insight about, and flexibility when, designing microstructures.
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Roham Sadeghi Tabar, Kristina Wärmefjord, Rikard Söderberg, Lars Lindkvist
J. Mech. Des. Oct 2020, 142(10): 102001 (8 pages) Paper No: MD-19-1377 https://doi.org/10.1115/1.4046436 The availability of big data has made the role of digital twins in manufacturing more prominent. This paper introduces a geometry assurance digital twin – created from the scanned data of individual components – to define and improve an assembly’s geometrical quality. The joining sequence in a sheet metal assembly impacts geometrical quality and determining the optimal joining sequence is computationally expensive. Meta-heuristic optimization techniques like genetic algorithms often require many simulations, which can increase computational cost. This work improves the optimization process by combining a model-based heuristic algorithm – based on contact displacement minimization – with the meta-heuristic algorithm. Contact modeling avoids part penetration in adjacent areas, and the joining sequences that provide minimal penetration states are used to populate the initial solution for the meta-heuristic algorithm. This approach is demonstrated on two sheet metal assemblies and a reduction in sequence time of 60-80% is achieved. By using a digital twin, optimal joining solutions can be achieved with greater efficiency.
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Conceptualizing Stable States in Origami-Based Devices Using an Energy Visualization Approach
Jacob Greenwood, Alex Avila, Larry Howell, Spencer Magleby
J. Mech. Des. Sep 2020, 142(9): 093302 Paper No: MD-19-1566 Origami can provide unique inspiration when designing engineered systems because it promotes multiple configurations, compact storage, and quick deployablility. However, origami-based products can be challenging to design because they often are mechanically unstable – folding when not desired or when under load. While there are some existing techniques for achieving stability in origami-based designs, determining which combination of techniques will achieve the desired results for a given application can be difficult. For example, how can you design an origami-based ballistic barrier to stay upright when you need it for protection, but also stay collapsed for storage?
The motivation of this research was twofold: to (1) develop a method for designing origami-based devices with multiple stable fold states, and (2) help engineers identify which stability techniques would be best for their application. This paper presents the Origami Stability Integration Method (the OSIM), an 8-step design method to help engineers achieve single or multiple stable positions in origami-based products. The OSIM helps the designer visualize how the different existing loads affect the movement of the origami-based device. Existing stability techniques are categorized to help the designer select appropriate techniques for their specific application, and a number of origami-based design considerations and resources related to stability are also included. The categorization is partially derived from a study of 69 origami-based products that were evaluated to determine which techniques are being used in products and how often they are used. Case studies of an origami-based anti-buckling guide for a medical catheter and an origami-based ballistic barrier are presented. 
Graphical representation of a methodology to design stable states for an origami-based folding system on the left and an example of its use for a deployable ballistic barrier on the right.
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Evaluating the Use of Virtual Reality to Teach Introductory Concepts of Additive Manufacturing
John K. Ostrander, Conrad S. Tucker, Timothy W. Simpson, Nicholas A. Meisel
J. Mech. Des. May 2020, 142(5): 051702 Additive manufacturing (AM) is becoming more prevalent in the classroom. Most AM education, though, is limited to desktop-scale material extrusion printers since they are relatively safe, easy to use, and inexpensive. However, industry demand continues to rise for students skilled in more advanced forms of AM, such as laser-based, metal powder bed fusion. Unfortunately, the cost, infrastructure, and training necessary for using these complex systems in education present challenges for classroom implementation. This research proposes using virtual reality (VR) as a medium for teaching introductory concepts of AM without the need for a physical printing system located in the classroom. Changes in student knowledge are identified using a pre-/post-AM lesson evaluation and student-reported changes in self-efficacy. Results showed no overall significant difference between knowledge gained in the physical AM environment and knowledge gained in the VR environment. This suggests that VR could be used as a successful approach for teaching AM concepts if cost, space, or infrastructure make it difficult to implement a physical industrial-scale AM system. There was also no significant difference found in knowledge gained in a passive VR environment when compared with an interactive VR environment. This suggests that even simple, accessible, low-cost VR solutions (such as Google Cardboard) could be used to educate the future AM workforce.
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Kevin Otto, Katja Hölttä-Otto, Roozbeh Sanaei, Kristin L. Wood
J. Mech. Des. Apr 2020, 142(4): 041402 This paper considers systems with field constraints, when elements cannot be placed in special regions such as a high-temperature field, a high-pressure field, a high magnetic field, etc. Fields place constraints on architectural modularity choices and provide creative opportunities for the design of complex systems. This paper develops practical design guidelines for modularity by considering field constraints and highlighting on a system block diagram which elements are within a high field region. The ideas are demonstrated on a medical contrast injector that must partially operate in magnetic and sterile fields. These field constraints are shown to be designer choices: by changing the design concept one can move functional elements into or out of fields. This approach provides opportunities for innovation through a focus on moving field boundaries to generate new product-system architecture concepts. For the medical contrast injector device, an exemplar innovation for higher accuracy dosage was moving the pump away from the motor into the magnetic field through an umbilical drive. Overall, field boundaries are inherent considerations in product architecture, and the techniques in this paper provide a foundational set of guidelines and a general approach for designing systems within such considerations.
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Guanglu Zhang, Elissa Morris, Douglas Allaire, Daniel A. McAdams
J. Mech. Des. Aug 2020, 142(8): 081401 Pubished online: February 14, 2020 Many modern products, such as automobiles, aircrafts, laptops and smartphones, are engineered systems. The performance, function, and architecture of an engineered system continuously changes and improves over time. For example, cell phones of the 1990’s were limited to phone calls and text messages. Today’s cell phones are computers capable of cinematography and reading the news. Research in engineered system evolution goes beyond tracking and predicting the technical performance and the functional and architectural changes of existing engineered systems. This research also studies how and why these changes occur and searches for causal factors behind these evolutions. The results of this research are valuable for designers, R&D managers, investors, and policy makers by aiding the generation of innovative design concepts, setting reasonable R&D targets, investing in promising technologies, and developing effective incentive policies. This paper summarizes key research questions, identifies pioneering literature, and discusses the opportunities and challenges for future research in engineered system evolution. Importantly, a free access database is provided for facilitating future research in this area. The database currently includes more than 100,000 data points that belong to 31 technical performance metric categories of 7 engineering systems (i.e., passenger aircraft, orbital launch system, automobile, computer, refrigerator, lamp, and direct-fire ground weapon systems) and their components.
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Data-Driven Design Space Exploration and Exploitation for Design for Additive Manufacturing
Yi Xiong, Pham Luu Trung Duong, Dong Wang, Sang-In Park, Qi Ge, Nagarajan Raghavan, David W. Rosen
J. Mech. Des. Oct 2019, 141(10): 101101 The capabilities of additive manufacturing offer significant potential for revolutionizing existing product development processes by creating products that are rich in shape, material, hierarchical, and functional complexities. However, searching through design solutions in such a multidimensional design space is a challenging task. In this study, the authors propose a holistic approach that applies data-driven methods in successive stages of design search and optimization. More specifically, a two-step surrogate model-based design method is proposed for the embodiment and detailed stages of product design. A Bayesian network classifier is used in embodiment design as the reasoning framework for exploring the design space. A Gaussian process regression model is then used as the evaluation function during optimization, allowing for the exploitation of the design space during the optimization of the detailed design. These models are constructed based on one dataset created using Latin hypercube sampling and then refined using Markov Chain Monte Carlo sampling. This cost-effective data-driven approach is demonstrated by designing a customized ankle brace that has tunable mechanical performance by using a highly stretchable design concept with tailored stiffnesses in different directions. 
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A Spatial Grammar Method for the Computational Design Synthesis of Virtual Soft Locomotion Robots
Merel van Diepen and Kristina Shea
J. Mech. Des 141(10), 101402; doi: 10.1115/1.4043314 Soft locomotion robots are intrinsically compliant and have a large number of degrees of freedom. However, the hand-design of soft robots is often a lengthy trail-and-error process. This paper presents the computational design of virtual, soft locomotion robots using an approach that integrates simulation feedback. The Computational Design Synthesis (CDS) approach consists of three stages: (1) generation, (2) evaluation through simulation, and (3) optimization.
Designs are generated using a spatial grammar that explicitly guides the type of solutions generated and excludes infeasible designs. The soft material simulation method is stable and sufficiently fast for use in a highly iterative simulated annealing search process. The resulting virtual designs exhibit a large variety of expected and unexpected gaits, thus demonstrating the capabilities of the method. Finally, the optimization results and the spatial grammar are analyzed to understand and map the challenges of the problem and the search space. 
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Mohammad Hassannezhad, Marco Cantamessa, Francesca Montagna and P. John Clarkson
J. Mech. Des 141(8), 081101; doi: 10.1115/1.4042614 A key challenge in lengthy and labor-intensive design projects is leveraging knowledge and expertise. Tools are needed that reflect the social and technical characteristics of design processes. Such integrated modelling is particularly critical in the early stages of design where information is imprecise and decisions have significant consequence. This paper contributes to the development of Actor-Based Signposting (ABS) – a dynamic method that combines the Activity-based and Agent-based concepts of process modelling. This approach enables individuals to be adaptive in satisfying the local objectives of their own jobs while complying with the global objectives of the rest of the team/entire system. Outcomes from this work are significant because they can be used for predicting the trajectory of a design process by allowing decision-makers to understand what task to do next, whom to assign a task given the availability of resources, and the levels of knowledge and expertise required. Two case studies are presented and results demonstrate a range of insights that could enhance managers’ decision-making capabilities and opportunities for future research are discussed.
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Dawei Li, Ning Dai, Yunlong Tang, Guoying Dong, and Yaoyao Fiona Zhao
J. Mech. Des 141(7), 071402 doi: 10.1115/1.4042617 Periodic cellular structures with excellent mechanical properties widely exist in nature. Examples include shark skin, bone structure, etc. This research introduces a generative design and optimization method for triply periodic level surface (TPLS)-based functionally graded cellular structures. In the proposed method, the density distribution is controlled so that the TPLS-based cellular structures can achieve better structural or thermal performances without increasing the weight of the structure. A series of different design specifications are used for validating the design and optimization methods introduced in this work. Effectiveness and robustness of the obtained structures are analyzed using both finite element analysis and experiments. Results from these studies show that the functional gradient cellular structure is much stiffer and has better heat conductivity than the uniform cellular structure.
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FEATURESThis section includes brief descriptions of articles soon to be or recently published by the Journal of Mechanical Design. These featured articles highlight recent research developments and emerging trends in mechanical design. For Abstracts and Full Articles please see ASME’s Digital Collection. Archives
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