Toward a Methodology for Systematically Generating Energy- and Materials-Efficient Concepts Using Biological Analogies
Energy- and materials-efficient designs are highly valued in the context of sustainable product design, but realizing products with significant changes in efficiency is difficult. One means to address this challenge is to use biological analogies during ideation. The use of biological analogies in the design process has been shown to greatly increase the novelty of concepts generated, and many authors in the bioinspired design (BID) community contend that efficiency-related benefits may be conferred as well. However, there is disagreement in the field as to when, how, and why efficiency-related benefits might arise in BIDs. This work explores these issues in-depth. A review of BID literature and an empirical study of BIDs lead to a better understanding of the types of efficiency advantages conferred by BID and set the stage for the development of tools and methods to systematically generate more energy- and materials-efficient design concepts using biological analogies.
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Redundancy Allocation Optimization for Multistate Systems With Failure Interactions Using Semi-Markov Process
Adding redundancy is a widely used method in engineering to improve the system reliability. How to add redundancy, (i.e., to meet the reliability requirement with the minimum cost), is an interesting topic in system design. Traditionally, the optimal redundancy allocation scheme is obtained under two simplified assumptions, i.e., binary states of each component and no failure dependency between components. The binary-state assumption assumes that each component and the entire system can only have two states: fully operational and completely failed. The failure independency assumption assumes no failure interaction between components, i.e., one component failure will not affect the failure process of other components. Although those two assumptions can simplify the analysis, they may lead to inaccurate reliability predictions and thus results in doubtful and misleading redundancy allocation scheme which in fact may not meet the reliability requirement. This work proposes a method to obtain the optimal redundancy allocation scheme by using the Semi-Markov process and optimization techniques without those two simplified assumptions. The target system is a type of commonly-seen system having multiple states and failure interactions. The target system contains a main subsystem providing the required output and an auxiliary subsystem helping the main subsystem function normally, such as the rotating subsystem and the lubricating subsystem, the computer mother board and the fan, and so on. A case study of a shipboard power electronic cabinet demonstrates the applicability of the proposed approach.
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Kazuko Fuchi, Philip R. Buskohl, Giorgio Bazzan, Michael F. Durstock, Gregory W. Reich, Richard A. Vaia and James J. Joo
J. Mech. Des 137(9), 091401; doi: 10.1115/1.4030876
Origami structures morph between 2D and 3D configurations, and their efficient shape reconfigurations show potential for many engineering applications. However, the enormity of the design space and the complex relationship between origami-based geometries and engineering metrics place a severe limitation on design strategies based on intuition. This work proposes a physics-based origami design method using topology optimization that determines an optimal crease pattern for a folding by adding or removing folds based on a design metric. Optimization techniques and mechanical analysis are also co-utilized to identify an action origami building block and determine the optimal network connectivity between multiple actuators.
We have developed an improved deformable Underconstraint Eliminator (UE) linkage for removing underconstraint, which causes unwanted resonances and reduced stiffness at large displacements, in linear flexure bearings. Linear flexure bearings deform to permit high repeatability, fine resolution translational motion. This new linkage alleviates many of the problems associated with current linkage solutions such as static and dynamic performance losses and increased bearing size. The nested linkage design is shown through analysis and experiment to work as predicted in selectively eliminating the underconstrained degrees of freedom (DOF) in linear flexure bearings. The improved bearing shows a >10x gain in the resonance frequency and >100x gain in static stiffness of the underconstrained DOF, as designed. Analytical expressions are presented for designers to calculate the performance of the new UE linkage. The linear nested linkage concept is also generalized to a rotary flexure design.
Fig. 1. a) Flexure bearing with the new nested underconstraint eliminator (UE) linkage. This linkage selectively removes the underconstraint inherent in the bearing design by linking the motion of the intermediate and final stage. b) Schematic of the UE linkage, this is the triangular structure in the center, enabled by flexures (11, 12, and 2), which does not impede the motion of the bearing flexures (m). The possible motion for the structure is shown in the equivalent linkage model in c).
This 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.