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Research Papers: Design Theory and Methodology

J. Mech. Des. 2016;139(2):021101-021101-13. doi:10.1115/1.4035054.

Modular design is an effective approach to shorten lead-time and reduce cost for development of complex products and systems (CoPS). Because the physical details of the product are not available at the conceptual design stage, considerations in the downstream product development phases such as manufacturing and assembly cannot be used for partition of modules at the conceptual design stage. Since design solution at the conceptual design stage can be modeled by functions and relationships among these functions such as function flows including information flows, material flows, and energy flows, a novel approach is introduced in this research for function module partition of CoPS through community detection using weighted and directed complex networks (WDCN). First, the function structure is obtained and mapped into a weighted and directed complex network. Based on the similarity between behaviors of communities in WDCN and behaviors of modules in CoPS, a LinkRank-based community detection approach is employed for function module partition through optimization with simulated annealing. The function module partition for the power mechanism in a large tonnage crawler crane is conducted as a case study to demonstrate the effectiveness of the developed approach.

Commentary by Dr. Valentin Fuster
J. Mech. Des. 2017;139(2):021102-021102-10. doi:10.1115/1.4035428.

Designers frequently utilize engineering equipment to create physical prototypes during the iterative concept generation and prototyping phases of design. Currently, evaluating designers' efficiency during prototype creation is a manual process that either involves observational or survey based approaches. Real-time feedback when using engineering equipment has the potential to enhance designers' efficiency or mitigate potential injuries that may result from incorrect use of equipment. Toward an automated approach to addressing these challenges, the authors of this work test the hypotheses that (i) there exists a difference in designers' comfort levels before and after they use a piece of engineering prototyping equipment and (ii) a machine learning model predicts the level of comfort a designer has while using engineering prototyping equipment with accuracies greater than random chance. It has been shown that the level of comfort that an individual has while completing a task impacts their performance. The authors investigate whether automatic tracking of designers' facial expressions during prototype creation predicts their level of comfort. A study, involving 37 participants using various engineering equipment, is used to validate the approach. The support vector machine (SVM) regression model yielded a range of R squared values from 0.82 to 0.86 for an equipment-specific model. A general model built to predict comfort level across all engineering equipment yielded an R squared value of 0.68. This work has the potential to transform the manner in which design teams utilize engineering equipment toward more efficient concept generation and prototype creation processes.

Commentary by Dr. Valentin Fuster
J. Mech. Des. 2017;139(2):021103-021103-12. doi:10.1115/1.4035430.

Customer demands and global markets prompt companies to offer increasing product variety. The use of modular product structures is a possible strategy for providing the necessary external variety to the market and reducing costs by lowering internal variety within the company. Current research provides several approaches for developing modular product family structures. As modularity is a gradual property, these methods generate different product structure concepts and companies have to decide at an early stage and without detailed information which concepts to implement. Most existing modularization methods offer only little or no support for decision making, particularly in terms of cost effects. This article illustrates the cost effects of variety and modular product family structures, the various cost impacts of variety management strategies and modularization methods in a literature review. A new approach to quantify these cost effects to support concept selection during modular product family design is introduced.

Commentary by Dr. Valentin Fuster

Research Papers: Design Automation

J. Mech. Des. 2016;139(2):021401-021401-10. doi:10.1115/1.4034883.

Static structural aeroengine components are typically designed for full lifetime operation. Under this assumption, efforts to reduce weight in order to improve the performance result in structural designs that necessitate proven yet expensive manufacturing solutions to ensure high reliability. However, rapid developments in fabrication technologies such as additive manufacturing may offer viable alternatives for manufacturing and/or repair, in which case different component lifing decisions may be preferable. The research presented in this paper proposes a value-maximizing design framework that models and optimizes component lifing decisions in an aeroengine product–service system context by considering manufacturing and maintenance alternatives. To that end, a lifecycle cost model is developed as a proxy of value creation. Component lifing decisions are made to minimize net present value of lifecycle costs. The impact of manufacturing (represented by associated intial defects) and maintenance strategies (repair and/or replace) on lifing design decisions is quantified by means of failure models whose output is an input to the lifecycle cost model. It is shown that, under different conditions, it may not be prudent to design for full life but rather accept shorter life and then repair or replace the component. This is especially evident if volumetric effects on low cycle fatigue life are taken into account. It is possible that failure rates based on legacy engines do not translate necessarily to weight-optimized components. Such an analysis can play a significant supporting role in engine component design in a product–service system context.

Commentary by Dr. Valentin Fuster
J. Mech. Des. 2016;139(2):021402-021402-14. doi:10.1115/1.4035051.

Research in market-based product design has often used compensatory preference models that assume an additive part-worth rule. These additive models have a simple, usable form and their parameters can be estimated using existing software packages. However, marketing research literature has demonstrated that consumers sometimes use noncompensatory-derived heuristics to simplify their choice decisions. This paper explores the quality of optimal solution obtained to a product line design search when using a compensatory model in the presence of noncompensatory choices and a noncompensatory model with conjunctive screening rules. Motivation for this work comes from the challenges posed by Bayesian-based noncompensatory models: the need for screening rule assumptions, probabilistic representations of noncompensatory choices, and discontinuous choice probability functions. This paper demonstrates how respondents making noncompensatory choices with conjunctive rules can lead to compensatory model estimations with distinct respondent segmentation and relative, large absolute part-worth values. Results from a product design problem suggest that using a compensatory model can provide benefits of smaller design errors and reduced computational costs. Product design optimization problems using real choice data confirm that the compensatory model and the noncompensatory model with conjunctive rules provide comparable solutions that have similar likelihoods of not being screened out when using a consideration set verifier. While many different noncompensatory heuristic rules exist, the presented study is limited to conjunctive screening rules.

Commentary by Dr. Valentin Fuster
J. Mech. Des. 2016;139(2):021403-021403-7. doi:10.1115/1.4035186.

Mathematical models simulating the handling behavior of passenger cars are extensively used at a design stage for evaluating the effects of new structural solutions or control systems. The main source of uncertainty in these type of models lies in tire–road interaction, due to high nonlinearity. Proper estimation of tire model parameters is thus of utter importance to obtain reliable results. This paper presents a methodology aimed at identifying the magic formula-tire (MF-Tire) model coefficients of the tires of an axle only based on measurements carried out on board vehicle (vehicle sideslip angle, yaw rate, lateral acceleration, speed, and steer angle) during standard handling maneuvers (step-steers, double lane changes, etc.). The proposed methodology is based on particle filtering (PF) technique. PF may become a serious alternative to classic model-based techniques, such as Kalman filters. Results of the identification procedure were first checked through simulations. Then, PF was applied to experimental data collected using an instrumented passenger car.

Commentary by Dr. Valentin Fuster
J. Mech. Des. 2016;139(2):021404-021404-9. doi:10.1115/1.4034970.

The art and science of folding intricate three-dimensional structures out of paper has occupied artists, designers, engineers, and mathematicians for decades, culminating in the design of deployable structures and mechanical metamaterials. Here we investigate the axial compressibility of origami cylinders, i.e., cylindrical structures folded from rectangular sheets of paper. We prove, using geometric arguments, that a general fold pattern only allows for a finite number of isometric cylindrical embeddings. Therefore, compressibility of such structures requires either stretching the material or deforming the folds. Our result considerably restricts the space of constructions that must be searched when designing new types of origami-based rigid-foldable deployable structures and metamaterials.

Commentary by Dr. Valentin Fuster
J. Mech. Des. 2017;139(2):021405-021405-11. doi:10.1115/1.4035493.

The lubrication system is one of the most important subsystems in gasoline internal combustion engines (ICEs), which provides hydrodynamic lubrication for friction pairs. The performance of the lubrication system affects the performance of the engine directly. The objective of this work is to reduce the friction loss of the engine and the driven power of the oil pump through design optimization. Two most important oil consumers in the lubrication system are investigated using multibody dynamics (MBD) and elastohydrodynamics (EHD). Considering that MBD and EHD analyses are time-consuming, Kriging is applied to establish the approximation models for bearings. Multi-objective optimization of bearings based on approximation models is formulated and conducted. Given the difference among multiple cylinders in the engine, a bilevel optimization framework is used to perform bearing optimization. The oil consumption and the friction loss of the bearings are reduced within the entire speed range. After that, the pipe diameters of the lubrication system are optimized with optimized bearings to reduce the flow resistance. With the optimization of both bearings and lubrication pipes in a sequential manner, the oil pressure is maintained at the baseline level while the oil pump size is reduced, and the driven power is averagely dropped over the entire speed range.

Commentary by Dr. Valentin Fuster

Research Papers: Design of Mechanisms and Robotic Systems

J. Mech. Des. 2016;139(2):022301-022301-10. doi:10.1115/1.4035053.

In the last decades, grippers have been employed extensively at the microscale, for example, in microbiology and in microassembly. In these fields, specifically, it is essential to improve the performance of these systems in terms of precision, actuation, and sensing of the gripping force. Recent investigations drew attention on the tip–environment interaction force, which gave rise to further studies on the tip compliance behavior. This paper reveals a new method for designing MEMS technology-based compliant microgrippers with prescribed specifications for the jaw tip compliance. This approach relies on the equivalence between a compliant mechanism and its corresponding pseudorigid-body model (PRBM), the former embedding conjugate surfaces flexure hinges (CSFHs) as flexures. Such correspondence has been assessed by means of finite element analysis (FEA) simulations and theoretical models.

Commentary by Dr. Valentin Fuster
J. Mech. Des. 2016;139(2):022302-022302-11. doi:10.1115/1.4035003.

In this paper, a class of large deployable mechanisms constructed by plane-symmetric Bricard linkages is presented. The plane-symmetric Bricard linkage is a closed-loop overconstrained spatial mechanism composed of six hinge-jointed bars, which has one plane of symmetry during its deployment process. The kinematic analysis of the linkage is presented from the perspectives of geometric conditions, closure equations, and degree-of-freedom. The results illustrate that the linkage has one degree-of-freedom and can be deployed from the folded configuration to one rectangle plane. Therefore, the plane-symmetric Bricard linkage can be used as a basic deployable unit to construct larger deployable mechanisms. Four plane-symmetric Bricard linkages can be assembled into a quadrangular module by sharing the vertical bars of the adjacent units. The module is a multiloop deployable mechanism and has one degree-of-freedom. The singularity analysis of the module is developed, and two methods to avoid singularity are presented. A large deployable mast, deployable plane truss, and deployable ring are built with several plane-symmetric Bricard linkages. The deployment properties of the large deployable mechanisms are analyzed, and computer-aided design models for typical examples are built to illustrate their feasibility and validate the analysis and design methods.

Commentary by Dr. Valentin Fuster

Technical Brief

J. Mech. Des. 2016;139(2):024501-024501-6. doi:10.1115/1.4035055.

Hydrodynamic drives, hydraulic drives, and friction drives have the common characteristics of continuously variable ratio but lower efficiency in comparison with gear meshing drive. A novel method for the design of power-cycling variable transmission (PCVT) has been proposed, which has the characteristics of continuously variable ratio and high efficiency in the whole working range. First, the power-cycling phenomena of powertrain system have been analyzed, and the basic configuration of PCVT system has been put forward. The feasible judgment criteria and the basic design principle of PCVT system are provided. The calculation formulas of speed ratio characteristic and efficiency characteristic of PCVT system are also derived. At last, the design patterns of PCVT system have been provided for illustrating the unique performance of PCVT system.

Commentary by Dr. Valentin Fuster
J. Mech. Des. 2016;139(2):024502-024502-4. doi:10.1115/1.4035320.

Matching of orthopedic plates and bony surfaces does not have a high certainty of success because bone anatomy differs among individuals. Considering that surfaces of both orthopedic plates and bones manifest themselves as freeform surfaces and are especially suitable for surface feature-based design, a novel surface feature-based method for designing orthopedic plates is put forward, with detailed steps as follows. First, the bone surface feature (BSF) is established through feature representation of an average bone surface model, obtained based on the investigated samples. Second, the abutted surface of an orthopedic plate is established directly based on the BSF surface to increase matching between the plate and bony surface. The abutted surface feature (ASF) is then established through feature representation of the abutted surface. Third, the hierarchical mapping relationship between BSF and ASF is setup based on the framework of “three-level parameters and two-grade mappings.” The result is that semantic parameters defined on BSF and ASF are separated as an operation interface to make it convenient to edit orthopedic plates according to bone sizes. Finally, the orthopedic plate is generated by thickening the abutted surface, which is generated based on parameters defined on BSF. Taking radius as an example, a group of volar plates suitable for distal radius with different sizes are generated, showing that the proposed method is valid and feasible. Meanwhile, biomechanical stresses of designed volar plates are analyzed with finite element analysis, and the result shows that designed volar plates have good structural strength.

Commentary by Dr. Valentin Fuster

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