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Accepted Manuscripts

BASIC VIEW  |  EXPANDED VIEW
Review Article  
Matteo Verotti, Alden Dochshanov and Nicola Pio Belfiore
J. Mech. Des   doi: 10.1115/1.4036351
An Atlas of 98 microgrippers that recently appeared in Literature is herein presented by using four different forms: a) a restyled layout of the original mechanical structure, b) its corresponding pseudo-rigid body model (PRBM), c) its kinematic chain and, finally, d) its related graph. Homogeneity in functional sketching (a) is assumed to be greatly helpful to understand how these grippers work and what are the most significant differences between them. Therefore, a unified and systematic set of aesthetics and proportionality criteria have been adopted. Analogously, unified criteria for obtaining pseudo-rigid (b), kinematic (c), and graph (d) representations have been also used, which made the Atlas easy to be read and inspected. The distinction among lumped and distributed compliance has been also accepted to develop the structure of the Atlas. A companion paper has been prepared to present a survey on the variety of operational strategies that are used in these microgrippers.
Review Article  
Alden Dochshanov, Matteo Verotti and Nicola Pio Belfiore
J. Mech. Des   doi: 10.1115/1.4036352
This article provides an overview of the operational strategies adopted in microgrippers design. The review covers microgrippers recently proposed in Literature, some of which have been systematically presented in a companion paper, where their topological, kinematic and structural characteristics are discussed. In the present contribution the prevalent actuation methods and the operational aspects are discussed: the tip displacement, the tip force, the actuation voltage and the amplification factor are the reference parameters that are adopted to compare the different types of actuation and operational strategies. In addition, the control strategies and control algorithms currently adopted are reviewed.
research-article  
Yi-Pei Shih
J. Mech. Des   doi: 10.1115/1.4036353
A recent addition to the many milling processes used in manufacturing to cut straight bevel gears is a new face-hobbing method that uses a virtual hypocycloid straight-lined mechanism to produce straight-lined teeth. Despite earning much attention because of its high productivity, however, this method is unable to handle lengthwise crowning on tooth surfaces, which results in poor contact performance. This paper therefore proposes a novel lengthwise crowning method, applicable on a modern six-axis CNC bevel gear cutting machine, in which the gear blank performs a swinging motion during machining. This swinging motion is enabled by machine setting modifications, which here are derived from a mathematical model of a double (profile and lengthwise) crowned gear. After the model’s correctness is confirmed using ease off and tooth contact analyses, a final investigation examines the effect of two key parameters related to contact performance indexes whose interrelations are graphed to provide a designer reference.
Design Innovation Paper  
Christopher A. Mattson, Amy E. Wood and John Renouard
J. Mech. Des   doi: 10.1115/1.4036304
This paper presents a case study in engineering for global development. It introduces the Village Drill, which is an engineered product that has now – five years after its introduction to the market – enabled hundreds of thousands of people across 15 countries and three continents to have access to clean water. The Village Drill creates a 15 cm (6 inch) borehole as deep as 76 m (250 feet) to reach groundwater suitable for drinking. The case study presents facts for the actual development and sustaining and are unaltered for the purpose of publication. This approach provides the reader with a realistic view of the development time, testing conditions, fundraising, and the work needed to sustain the drill through five years of sales and distribution. The purpose of the case study is to provide sufficient and frank data about a real project so as to promote discussion, critique, and other evaluations that will lead to new developments that inspire and inform successful engineering for global development. As part of the case, the paper describes six fundamental items; the product, the customer, the impact, the manufacturing, the delivery, and the revenue model of the drill.
TOPICS: Drills (Tools), Testing, Sales, Water, Groundwater, Manufacturing
research-article  
Sree Kalyan Patiballa and Girish Krishnan
J. Mech. Des   doi: 10.1115/1.4036305
Design synthesis of distributed compliant mechanisms is often a two-stage process involving (a) conceptual topology synthesis, and a subsequent (b) refinement stage to meet strength and manufacturing specifications. The usefulness of a solution is ascertained only after the sequential completion of these two steps, which are in general computationally intensive. This paper presents a strategy to rapidly estimate final operating stresses even before the actual refinement process. This strategy is based on the uniform stress distribution metric, and a functional characterization of the different members that constitute the compliant mechanism topology. Furthermore, the paper uses the underlying mechanics of stress bound estimation to propose two rule of thumb guidelines for insightful selection of topologies, and systematically modifying them for an application. The selection of the best conceptual solution in the early stage design avoids refinement of topologies that inherently may not meet the stress constraints. The paper presents two examples that illustrate these guidelines through the selection and refinement of topologies for a planar compliant gripper application.
TOPICS: Stress, Design, Compliant mechanisms, Topology, Manufacturing, Grippers, Stress concentration
research-article  
Venkata Kamesh Vinjamuri, Mallikarjuna Rao Kuchibhotla and Balaji Srinivasa Rao Annambhotla
J. Mech. Des   doi: 10.1115/1.4036306
Epicyclic gear trains are used in the mechanical energy transmission systems where high velocity ratios are needed in a compact space. It is necessary to eliminate duplicate structures in the initial stages of enumeration. In this paper, a novel and simple method is proposed using a parameter, Vertex Incidence Polynomial (VIP) to synthesize Epicyclic gear trains up to 6 links eliminating all isomorphic gear trains. Each epicyclic gear train is represented as Graph by denoting gear pair with thick line and transfer pair with thin line. All the permissible graphs of epicyclic gear trains from the fundamental principles are generated by the recursive method. Isomorphic graphs are identified by the calculating VIP. Another parameter ‘Rotation Index’ (RI) is also proposed to detect Rotational isomorphism. It is found that there are 6 non-isomorphic rotation graphs for 5-link 1-dof and 26 graphs for 6-link 1-dof Epicyclic gear trains(EGTs) from which all the non-isomorphic displacement graphs can be derived by adding the transfer vertices for each combination. The proposed method proved to be successful in clustering all the isomorphic structures into a group which in turn checked for rotational isomorphism. This method is very easy to understand and allows to perform isomorphism test in epicyclic gear trains.
TOPICS: Planetary gears, Polynomials, Trains, Rotation, Gear trains, Gears, Displacement
research-article  
Hai-Jun Su, Carlos Castro, Alexander E. Marras and Lifeng Zhou
J. Mech. Des   doi: 10.1115/1.4036216
DNA origami nanotechnology is a recently developed self-assembly process for design and fabrication of complex 3D nanostructures using DNA as a functional material. This paper reviews our recent progress in applying DNA origami to design kinematic mechanisms at the nanometer scale. These nanomechanisms, which we call DNA Origami Mechanisms (DOM), are made of relatively stiff bundles of double-stranded DNA (dsDNA), which function as rigid links, connected by highly compliant single-stranded DNA (ssDNA) strands, which function as kinematic joints. The design of kinematic joints including revolute, prismatic, cylindrical, universal and spherical are presented. The steps as well as necessary software or experimental tools for designing DOM with DNA origami links and joints are detailed. To demonstrate the designs, we presented the designs of Bennett four-bar and crank-slider linkages. Finally, a list of technical challenges such as design automation and computational modeling are presented. These challenges could also be opportunities for mechanism and robotics community to apply well developed kinematic theories and computational tools to the design of nanorobots and nanomachines.
TOPICS: Design, Kinematics, DNA, Computer simulation, Manufacturing, Molecular machines, Linkages, Design automation, Nanoscale phenomena, Nanostructures , Nanotechnology, Robotics, Computer software, Functional materials, Self-assembly
research-article  
Nathan Eng, Marco Aurisicchio and Rob Bracewell
J. Mech. Des   doi: 10.1115/1.4036129
Objective: Maps have long been advocated to support thinking with loosely-structured design information. This article presents research to evaluate the application of mapping software known as the Decision Rationale editor (DRed) in the aerospace engineering industry. Specifically the research explains what mapping methods are used, in what context engineers find them more or less useful and why. Method: Semi-structured interviews were performed with fourteen engineers representing diverse departments and experience levels to investigate DRed use. Nineteen use cases were collected ranging from high-profile, multiple-stakeholder projects to everyday individual work. Results: The results validate long-standing mapping methods like Design Rationale Capture and Root Cause Analysis, and provide practical evidence for new methods like Requirements Management and the Function Analysis Diagram as well as for informal ones like Personal Information Management. The context of mapping methods use tended towards: system-level decisions that cut across sub-system boundaries; irregular intervals between map applications; dealing with loosely-structured information; individual or small team collaborations; and application on problems without particular urgency. The reasons for use, as articulated by engineers, point towards support for design thinking, communication and planning. Conclusion: Using empirical evidence of its recurring use on high-profile design projects, this research shows that DRed is a powerful and practical tool for engineers in industry. The understanding gained on mapping software demonstrates a shift in emphasis from the enrichment of the engineering record to the provision of immediate cognitive benefits for engineers.
TOPICS: Engineering design, Computer software, Engineers, Design, Aerospace engineering, Teams, Collaboration, Root cause analysis
research-article  
Daniel R Herber, Tinghao Guo and James T. Allison
J. Mech. Des   doi: 10.1115/1.4036132
In this article a class of architecture design problems is explored with perfect matchings. A perfect matching in a graph is a set of edges such that every vertex is present in exactly one edge. The perfect matching approach has many desirable properties such as complete design space coverage. Improving on the pure perfect matching approach, a tree search algorithm is developed that more efficiently covers the same design space. The effect of specific network structure constraints and colored graph isomorphisms on the desired design space is demonstrated. This is accomplished by determining all unique feasible graphs for a select number of architecture problems, explicitly demonstrating the specific challenges of architecture design. \rrevision{With this methodology, it is possible to enumerate all possible architectures for moderate scale-systems, providing both a viable solution technique for certain problems and a rich data set for the development of more capable generative methods and other design studies.
TOPICS: Architecture, Design, Algorithms
Announcements  
Amy Suski
J. Mech. Des   doi: 10.1115/1.4025965
TOPICS: Design

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