Authors: Briana Lucero; Vimal K. Viswanathan; Julie S. Linsey; Cameron J. Turner
J. Mech. Des.. 2014; 136(12):121101-121101-11.
doi: 10.1115/1.4028280

This research defines the basis for a new quantitative approach for retrieving useful analogies for innovation based on the relevant performance characteristics of functions. The concept of critical functionality is the idea of identifying only a certain set of pertinent design functions that significantly define the functionality of the product.  A critical function (CF) is a function within a functional model whose performance directly relates to a Key Performance Parameter (KPP) of the system as a whole. These critical functions will enable multiple analogies to be presented to a designer by recognizing similar functionality across distant design domains and incorporating key performance criteria. The ultimate focus of this research project is to create a performance-metric-based analogy library, called the Design Analogy Performance Parameter System (D-APPS). By focusing on a select set of “critical” functions, more design domains can be included in the database facilitating analogy retrieval founded on the qualification of key performance parameters. Such is the case of the beam and bamboo analogy based upon the critical function of maintaining structural stability.

Authors: Changming Yang, Xiaoping Du
J. Mech. Des. 136(10), 101405 (2014) (8 pages) Paper No: MD-13-1534; 
doi: 10.1115/1.4028016 

Robust design makes product performance stable under variations and noises in the environment. So the product can work robustly even in harsh conditions. This work explores a way to measure the robustness of a product when it has multiple performance variables, such as strength, efficiency, and cost. These performance variables are dependent and oftentimes conflicting, meaning that improving one performance variable may make others worse. The robustness of the worst-case performance variable is used as an indicator of the robustness of the entire product. Analytical and numerical algorithms are developed to calculate the robustness. The work makes it easy to model the robust design optimization with multiple performance variables as the single-objective optimization, thereby increasing the effectiveness of the robustness design process.

Authors: Katherine Fu, Diana Moreno, Maria Yang, and Kristin L. Wood
J. Mech. Des. 136(11), 111102 (2014) (18 pages)
doi: 10.1115/1.4028289

Authors: Mark Fuge, Bud Peters and Alice Agogino 
J. Mech. Des. 136(10), 101103 (2014) (8 pages)doi: 10.1115/1.4028102

Authors: Tianyi Cai and Theodor Freiheit
J. Mech. Des. 136(10), 101701 (Jul 21, 2014) (12 pages)
doi: 10.1115/1.4027981

Customers want good value when they buy products. However, the value perceived by a customer is affected in part by the benefits they get from the product and the cost of designing the product. This paper discusses how managers can better assign work-hours and other resources necessary to design products. Designers use these resources to create and improve upon the benefits the product delivers but at a cost that determines how the customer sees its value. Since the cost from the design process can be uncertain, for example because customer needs evolve and may not be fully understood, designers may have to repeat design activities to ensure the design is correct - Figure 1.  A mathematical model is proposed that shows how resources are transformed into value. This model allows resources to be assigned to a design projects optimally to control costs. Examples of the model’s application demonstrate strategic and tactical resource assignment in scenarios developed from the computer industry and for design projects.

Figure 1 – Conceptual Model of Value Creation Cell

Authors: Christine A. Toh; Scarlett R. Miller 
J. Mech. Des. (2014); 136(9):091004-091004-8
doi: 10.1115/1.4027639

Interacting with example products is an essential and widely practiced method in engineering design, yet little information exists on how the representation (pictorial or physical) or interaction a designer has with an example impacts design creativity. This paper reports the results of a controlled study with first year engineering design students developed to investigate the impact of a designer’s interaction with either a 2D pictorial image or a 3D product and the resulting functional focus and creativity of the ideas developed. The results of this study reveal that physical examples have the ability to reduce design novelty and variety. Based on our results, we recommend that designers delay the use of physical examples during the early stages of conceptual design in order to retain a higher level of design creativity. In other words, designers should perform an initial round of brainstorming using pictorial examples before interacting with physical examples of existing products in an effort to broaden the solution space explored. Second, our results show that product dissection encourages more form-based novelty but less functional focus compared to visual inspection. Since designers interact with physical examples frequently, it is crucial that we identify the underlying factors that influence physical interactions impact on design creativity. Finally, our results show that great care should be taken in selecting example designs in the early stages of conceptual design since these interactions can greatly impact design outcomes.

Authors: Sachiko Ishida, Taketoshi Nojima and Ichiro Hagiwara
J. Mech. Des. 136(9), 091007 (2014) 
doi: 10.1115/1.4027848

A new approach for obtaining the crease patterns of foldable conical structures from crease patterns of cylindrical structures based on the origami folding theory using conformal mapping is presented in this paper. Mapping for flow with circulation, which is the so-called polar conversion, is demonstrated as an example. This mapping can be used to produce similar elements and maintain the regularity of fold lines. This is a significant advantage when the mapping approach is used to produce foldable structures, because

it is relatively easy to control angles between fold lines. Thus, this proposed approach enables us to design complex structures from simple original structures systematically, maintaining advanced characteristics particular to origami such as folding up spatial structures onto a plane and expanding them at will.

Crease patterns and physical model; (a): original crease pattern of cylindrical structure; (b): transformed crease pattern of conical structure after angle correction; (c): physical model of conical structure. Extracted from Fig. 4

For the Abstract and Full Article visit ASME's Digital Collection.

Authors: Lei Cui, Paul Cheong; Ridge Adamson, Thomas Johnson
J. Mech. Des. (2014); doi:10.1115/1.4028094

The Swan-Canning River, which features relatively shallow and slow-moving water with sandy soils, is the most important estuary system in Perth, Western Australia. Currently, the Department of Water Western Australia sends personnel to manually survey and collect water and sand samples at thirty-two routine sampling sites along the Swan-Canning River weekly. The excessively large monitoring areas make the sample collection a costly practice, and the safety of personnel is potentially put at risk during the seasonal collection of mosquito-larvae samples and the occasional collection of toxic-waste samples. At the Department of Mechanical Engineering, Curtin University, we developed the AmBot, an amphibious robot, to automate this operation. The major challenge in developing the AmBot lies in that the limited physical size of the robot allows only one type of propulsion system to be used both on land and on water. On the contrary, large amphibious robots that use wheels or track systems when on land can switch to propellers when on water. We took inspiration from centipedes and morphed the multi-leg actuation into tracks by simplifying each leg-mechanism into a track piece consisting of a base and a polystyrene-foam block. This design makes the tracks essentially both floats and paddles that are also capable of withstanding the weight of the vehicle. When on water, the tracks provide propulsion force and buoyancy so that the waterline is well controlled; when on land, the tracks effectively spread the contact force across multi-blocks, leading to effective actuation and low pressure on the sandy terrain, hence protecting the beach eco-system. The AmBot uses an Android-based remote-control system via the Internet, where the accelerometer, gyroscope, GPS, and camera on the Android device provide integrated navigation and monitoring sensing.  

Authors: M. J. Handschuh; A. Kahraman; M. R. Milliren 
J. Mech. Des. 2014; 136(6):061010-061010-10.
doi: 10.1115/1.4027337

A gear designer must specify a quality level for each gear that is suitable for the application at hand.  This means that the designed gear must meet all performance requirements in terms of strength, efficiency and noise within the ranges of manufacturing tolerances dictated by the quality level chosen.  This study presents a set of experimental and theoretical investigations of the effect of one type of manufacturing tolerance defining tooth spacing errors on gear tooth bending strength, which dictates tooth breakage failures.  A number of experiments performed by using gears having deterministic and random spacing errors are presented along with simulations to show a significant influence of spacing errors on root stresses.  A methodology is proposed to relate increases in root stresses to the spacing error tolerances directly.  This methodology allows determination of the stress amplification factors due to a certain range of spacing error tolerances as well as quantifying how much spacing error can be tolerated below a desired root stress limit.  

(a) Measured and (b) predicted root stresses of ten consecutive teeth of a spur gear having a certain random spacing error sequence (c), revealing significant tooth-to-tooth differences in root stress amplitudes.

 For the Abstract and Full Article visit ASME's Digital Collection.