bluuebunny/crossref_metadata_2025 huggingface dataset:
Performance Mapping and Motion Simulation of a 4UPS+PU Redundantly Actuated Parallel Manipulator
Authors: Gao Zhen , Zhang Dan
Published: March 2011

In this paper, a new 4UPS+PU redundantly actuated parallel manipulator is proposed. This mechanism possesses three degrees of freedom (DOF), one translation and two rotations. Different from general parallel manipulators, a passive leg is connected to both centers of the base and the moving platform to constrain the unwanted motion. The mobility study and inverse kinematic analysis are conducted. The reachable workspace is generated with boundary-searching based discretization method. The local and global performance indices including stiffness and dexterity and their atlas are investigated in details. Comprehensive simulation of kinematics, dynamics and proportional-integral-derivative (PID) position control are implemented based on Adams to evaluate and testify the high operational capacity and well motion characteristics.
Environmental Analysis of Consumer Products During the Conceptual Phase of Product Design
Authors: Bohm Matt R. , Haapala Karl R. , Poppa Kerry , Stone Robert B. , Tumer Irem Y.
Published: March 2011

This paper describes efforts taken to further transition life cycle analysis techniques from the latter, more detailed phases of design, to the early-on conceptual phase of product development. By using modern design methodologies such as automated concept generation and an archive of product design knowledge, known as the Design Repository, virtual concepts are created and specified. Streamlined life cycle analysis techniques are then used to determine the environmental impacts of the virtual concepts. As a means to benchmark the virtual results, analogous real-life products that have functional and component similarities are identified. The identified products are then scrutinized to determine their material composition and manufacturing attributes in order to perform an additional round of life cycle analysis for the actual products. The results of this research show that enough information exists within the conceptual phase of design (utilizing the Design Repository) to reasonably predict the relative environmental impacts of actual products based on virtual concepts.
A Joint Probability Approach to Multiobjective Optimization Under Uncertainty
Authors: Rangavajhala Sirisha , Mahadevan Sankaran
Published: March 2011

In this paper, we present a new approach to solve optimization problems with multiple objectives under uncertainty. Optimality is considered in terms of the risk that the overall system performance, as defined by all of the multiple objectives exceeding their desired thresholds, remains acceptable. Unlike the existing state-of-the-art, where first-order moments of the system level objectives are used to ensure optimality, we employ a joint probability formulation in our research. The Pareto optimality criterion under uncertainty is defined in terms of joint probability, i.e., probability that all system objectives are less than the desired thresholds. These thresholds can be viewed as the desired upper/lower bounds on the individual system objectives. The higher the joint probability, the more reliably the thresholds bound the system performance, hence the lower the overall system performance risk. However, a desirable high joint probability may necessitate undesirably high/low thresholds, and hence the tradeoff. In this context, the proposed method provides two decision-making capabilities: (1) Maximum probability design: given a set of threshold values for system objectives, find the design that yields the maximum joint probability (2) Optimum threshold design: Given a desired joint probability, find the set of thresholds that yield this probability. In this paper, optimization formulations are presented to solve the above two decision-making problems. A two-bar truss example and the conceptual design of a two-stage-to-orbit launch vehicle are presented to illustrate the proposed methods. The numerical results show that optimizing the mean values of the objectives individually does not necessarily guarantee the desired performance of all objectives jointly under uncertainty, which is of ultimate interest in multiobjective optimization.
Analysis of the Structure and Evolution of an Open-Source Community
Authors: Huang Hao-Yun , Le Qize , Panchal Jitesh H.
Published: March 2011

Open-source processes are based on the paradigm of self-organized communities as opposed to traditional hierarchical teams. These processes have not only been successful in the software development domain, but are increasingly being used in the development of physical products. In order to successfully adapt open-source processes to product realization there is a need to understand how open-source communities self-organize and how that impacts the development of the products. Towards the direction of fulfilling this need, we present an analysis of an existing open-source community involved in developing a web-based content-management platform, Drupal. The approach is based on the analysis of networks using techniques such as social network analysis, degree distribution, and hierarchical clustering. Openly available information on the Drupal website is utilized to perform the analysis of the community. The data is transformed into two weighted undirected networks: networks of people and networks of Drupal modules. Both the structure of these networks and their evolution during the past six years are studied. The networks are visualized by mapping them into images. Based on the analysis, it is observed that the structure of the Drupal community has the characteristics of a scale-free network, which is similar to many other complex networks in diverse domains. Finally, key trends in the evolution of the networks are identified and the possible explanations for those trends are discussed.
A Genetic Algorithm Based Optimization for Laminated Dies Manufacturing
Authors: Ahari Hossein , Khajepour Amir , Bedi Sanjeev
Published: March 2011

Laminated tooling is one of the new technologies which helps companies to manufacture parts with lower costs and higher accuracy. It is base on dividing entire CAD model of the part to slices and then cutting each layer profile utilizing laser cut or other techniques. Finally the layers are stacked together to make the final product. CNC machining removes the extra material and brings the part to the specific tolerances. In order to minimize the manufacturing cost, one option is reduction in the amount of the extra material and the number of slices likewise. This is considered as an optimization problem in this research. Then a genetic algorithms (G.A.) based method is offered to solve this optimization problem. However, as a common problem in most instances of genetic algorithms, premature convergence prevents system to continue searching for a more reliable solution after finding a local optimum. To address this problem, a novel niching method is presented in this paper. Results show a significant improvement in the quality of the solution as well as a considerable reduction in processing time.
Driver-Car Communication Would Introduce a Drastic Change in Vehicle Design
Authors: Fukuda Shuichi
Published: March 2011

This paper discusses the potential role of emotion in changing our machine design, based upon the experiments conducted for about 20 years by TMIT (Tokyo Metropolitan Institute of Technology) research group headed by the author. An automobile design shares the same issues as those in our future machine design. In order to clarify these points, experiment to detect driver’s emotion were carried out. Our research to detect driver’s emotion started from the observations of a driver in driving, and based on them, experiments to detect driver’s emotion from face, sound and body were carried out. The following points were made clear. (1) a driving simulator is not good because a subject is in a different state of mind and physical conditions from actual driving. (2) Dynamic image processing is valid, but to make it effective, a simple image processing technique must be developed and a technique to remove lighting change effects must be developed. (3) When detecting from face, feature points must be carefully chosen. (4) Although sound is very promising, drivers do not utter voices often and if they do, their durations are very short. But if we introduce voice guidance systems, which would be much easier in EVs, detection from sound would work far more effectively than that from dynamic image, because images are very difficult to process due to the frequently changing lighting. (5) Physical movements can be used very effectively to detect fatigue. (6) Physical movement may be utilized for safer driving. If a new communication system between a driver and a car can be developed, the design of a car would change drastically. We do not have to, for example, use a wheel to steer. We could use bars. Equipments can be placed far away from the driver, if voice guidance systems can be introduced. Thus, a far greater degree of design flexibility could be introduced and a driver and a car could work better together as a team.
Kinematic Acquisition of Geometric Constraints for Task Centered Mechanism Design
Authors: Wu Jun , Ge Q. J. , Su Hai-Jun , Gao Feng
Published: March 2011

A motion task can be given in various ways. It may be defined parametrically or discretely in terms of an ordered sequence of displacements or in geometric means. This paper studies a new type of motion analysis problem in planar kinematics that seeks to acquire geometric constraints associated with a planar motion task which is given either parametrically or discretely. The resulting geometric constraints can be used directly for type as well as dimensional synthesis of a physical device such as mechanical linkage that generates the constrained motion task. Methods for kinematic acquisition of geometric constraints bridge the gap between type and dimensional synthesis and provide the foundation for task centered mechanism design.
On the Modeling of Open and Breathing Cracks of a Cracked Rotor System
Authors: AL-Shudeifat Mohammad A. , Butcher Eric A.
Published: March 2011

The modeling of a cracked rotor system with an open or breathing transverse crack is addressed here. The cracked rotor with an open crack model behaves as an asymmetric shaft. Hence, the time-varying area moments of inertia of the cracked section are employed in formulating the periodic finite element stiffness matrix for both crack models which yields a linear time-periodic system. The harmonic balance method (HB) is used in solving the finite element (FE) equations of motions for studying the dynamic behavior of the cracked rotor system. The unique behavior of the whirl orbits during the passage through the subcritical rotational speeds and the sensitivity of these orbits to the unbalance force direction can be used for early crack detection of the cracked rotor for both crack models. These whirl orbits were verified experimentally for the open crack model in the neighborhood of 1/2 of the first critical rotational speed where a good match with the theoretical whirl orbits was observed.
Unified Modeling Language and Object-Oriented Design Pattern Based Computer-Aided Welding Fixture Design System
Authors: Li Hua , Rong Yiming
Published: March 2011

Most of previous computer aided fixture design (CAFD) research has mainly concentrated on machining fixtures rather than welding fixtures, and how to face the challenges such as dynamic requirements, expansion, maintenance and management in the development of complicated computer aided welding fixture design (CAWFD) software system has received much less attention. Application of Unified Modeling Language (UML) and Object-oriented Design Pattern (OODP) for developing CAWFD software system has been discussed in this paper. CAWFD system functions like design phases, workflow and design subtasks in each design phase are introduced. How to employ UML fundamental elements such as use case diagram, class diagram and component diagram to model the CAWFD system has been demonstrated. Multiple-tier architecture of CAWFD and its benefits are also presented. OODP has been certified to be an effective and efficient method especially for class diagram creation and refinement which is the key point during system analysis and design. Due to the complexity of CAWFD, the class diagram for CAWFD is classified as conceptual class diagram and detailed class diagram. How to use Model-View-Control (M-V-C) design pattern in conceptual class diagram and the benefits of M-V-C application are discussed. For detailed class diagram, the techniques of applying Command, Observer, Factory and Template patterns to realize code reuse are articulated. As a result, the extension, reusability and maintainability of CAWFD system can be obtained by applying UML and OODP.
Flattenable Mesh Processing by Controllable Laplacian Evolution
Authors: Lin Hongwei , Zhang Yunbo , Wang Charlie C. L. , Gao Shuming
Published: March 2011

Models represented by polygonal meshes have been more and more widely used in CAD/CAM systems. In sheet manufacturing industries, the flattenability of a model is very important. Prior methods for processing the flattenability of a mesh surface usually employ a constrained optimization framework, which takes the positions of all its non-boundary vertices as variables in computation. For a mesh surface with hundred thousands of vertices, solving such an optimization is very time-consuming, and may exceed the capacity of main memory. In this paper, we develop a controllable evolution method to process the flattenability of a given mesh patch. It decouples the global optimization problem into a sequence of local controllable evolution steps, each of which has only one variable. Therefore, mesh surfaces with large number of vertices can be processed.
The Robust Linkage Synthesis for Planar Rigid-Body Guidance
Authors: Al-Widyan Khalid , Angeles Jorge
Published: March 2011

The kinematic synthesis of planar motion generators in the presence of an incomplete set of finitely separated poses is the subject of this paper. Given that the planar rigid-body guidance problem in the realm of four-bar linkage synthesis can be solved exactly for up to five prescribed poses of the coupler link, any number of poses smaller than five is considered incomplete in this paper. The poses completing the set are determined so as to produce a robust linkage against variations in the unspecified poses. To this end, a theoretical framework for model-based robust design is invoked and a general methodology for robust kinematic synthesis is laid down. Robustness is needed in this context to overcome the presence of uncertainty due to the selection of the unprescribed poses, which many a time are left up to the mechanism designer’s judgment. To validate the concepts and illustrate the application of the methodology proposed here, an example is included.
Robust Management of Virtual Enterprises
Authors: Pego-Guerra Marco A. , Zhang W. J. , Ip W. H.
Published: March 2011

Management is one of the most challenging phases in life cycle of a Virtual Enterprise (VE). It has been found that nearly 70% of the VE cases disband prematurely. In many cases, this premature disbanding is caused by problems related to their management. In this paper, we present a study on analysis of robustness of the VE manufacturing system using the robust design technique. The objective of the study was to develop a methodology that allows for robustness analysis and show what and how variables of the VE system affect its robustness using this methodology. The study was a simulation-based experiment; in particular, the control factors were studied with an L18 experimental design, while the noise factors were with an L9 design. The Analytical Hierarchical Process (AHP) was used as the tool in this study to link the structure of a VE (namely a set of members) and the behavior of the VE (namely disband). The result of the experiment show the methodology is promising. In the science of the VE manufacturing system, this study concluded: (1) the best robustness can be achieved when the partners’ technical capabilities are considered more important than other criteria, (2) business-related criteria should be considered as equally important as other criteria, and (3) both controllable and uncontrollable factors are responsible for the robustness of the VE system in its life cycle.
Zeroth-Order Corrections to the Euler-Bernoulli Beam Model
Authors: Dankowicz Harry , Lacarbonara Walter
Published: March 2011

This paper compares the frequency-amplitude relationship for nonlinear oscillations of a geometrically nonlinear model of a slender beam in the absence of damping with the corresponding predictions from the Mettler model for the transverse motion. In particular, the analysis shows that the Mettler model fails to account for a constant, amplitude-independent shift in the nonlinear frequency relative to the linear frequency caused by rotary inertia terms.
Computer-Aided Modeling of the Principle Solution of Mechatronic Systems: A Domain-Spanning Methodology for the Conceptual Design of Mechatronic Systems
Authors: Gausemeier Ju¨rgen , Dorociak Rafał , Kaiser Lydia
Published: March 2011

Mechatronics — the symbiotic cooperation of mechanics, electrics/electronics, control engineering and software engineering — opens up more and more fascinating perspectives for the development of future mechanical engineering products. Still, development of mechatronic systems remains a challenge. To cope with this challenge a new domain-spanning design methodology for mechatronic systems is needed. This contribution presents a design methodology, which consists of a specification technique for the domain-spanning description of the principle solution of an advanced mechatronic system, a procedure model, which defines the constituent steps of the conceptual design, their results and their order, as well as software tool, which provides means for managing the design complexity and intuitive modeling of the principle solution. The advantages of the design methodology are demonstrated in a case study from the development of an autonomous miniature robot.
A Steady State Model of the Contact Between a Deformable Tire and a Deformable Terrain
Authors: Sanghvi Pravesh , Dankowicz Harry , Romig Bernard E.
Published: March 2011

This paper presents a lumped-parameter, planar, physical model for capturing steady-state interactions between a deformable tire and a deformable terrain. The model includes effects due to tangential and normal compliance of the terrain surface as well as radial and circumferential compliance of the tire. In addition, shear failure and dry friction limits are introduced through a distinction between regions along the circumferential direction of the tire that are in local stick or slip, respectively. The time history of interactions between individual infinitesimal patches of the tire and the terrain is then described by a hybrid dynamical system, in which changes between individual phases of motion are triggered by characteristic events. The paper further illustrates the application of a non-linear regression technique for identification of the seven model parameters and, in selected cases additional unknown kinematic variables. Specifically, the model is fit to experimental load-deflection, gross-thrust, and net-pull data demonstrating good quantitative agreement.
Vibration Analysis of Rotor-Fluid Film Bearing System Using Monte Carlo Method
Authors: Zhang Zhengkai , Zhang Youyun , Zhu Yongsheng
Published: March 2011

The rotor-fluid film bearing systems are widely used in machinery due to their small size, low price, and capability of carrying load. However, if its design and manufacturing is inappropriate, the use of rotor-fluid film bearing system will suffers from some problem such as violent vibration. Although the checking calculation has been carried out during the design process, nominal value of design parameters is usual used to prognosis the vibration characteristics of rotor-fluid film bearing system. However, in practice, these parameters always vary within a certain range due to manufacturing tolerances and variation of working environment. In this paper, a model for simulating the performance of rotor-fluid film bearing system has been established. Monte Carlo analysis was performed to evaluate the effects of manufacturing tolerances and variation of working environment on the rotor vibration. In the end, a uncertainty analysis is carried out to demonstrate which of the factors has the greatest effect on the rotor vibration at different rotational speed.
Concept-to-Value: Method and Tool for Value Creation in Conceptual Design
Authors: Rianantsoa Ndrianarilala , Yannou Bernard , Redon Romaric
Published: March 2011

This paper is dealing with the problem of steering the conceptual design by value. Indeed, the preliminary phase of the design process, which generates the innovative concepts that will be developed in detail, already defines broadly the created value of an innovation project. Contrarily to the detailed design that consists in design solutions refinement for well defined performances increase, the conceptual design is characterized by the fact that the design objects, like the design problems, the design concepts and knowledge, are not frozen, known or precised, and have to be defined progressively in a value creation way for customers and stakeholders. Since there are few works on this issue, we try then to suggest a conceptual design process based on the capture and evaluation of the generated intermediate objects for the maximization of the created value of this phase, and so of an innovative project. A descriptive model, a value model and a prescriptive production model of the intermediate objects are thus built and explained.
Physical Models in Idea Generation: Hindrance or Help?
Authors: Viswanathan Vimal K. , Linsey Julie S.
Published: March 2011

Engineering idea generation is a critical part of new product development and physical models are one tool used in this phase of design. Unfortunately, few guidelines about the effective use of physical models to support idea generation exist. The advantages and disadvantages of physical models need to be clarified so that engineers know when and where to implement them effectively. Previous literature indicates there is potential for design fixation on physical prototypes. This limits the solutions considered. In contrast, other recommendations encourage the extensive use of physical models and the psychological literature indicates that physical representations have the potential to lead to more feasible design by supporting designers’ mental models of physical phenomena. This study evaluates these questions with a between-subjects experiment with four conditions, sketching only, building, building & testing, and constrained sketching. No evidence for design fixation is observed. The results show that physical models supplement designers’ mental models, thereby leading to higher quality ideas (fraction of functional ideas). This result shows a potential way of improving designer’s innovation by strategically implementing fast and cheap prototyping methods.
Realization of a Planar Stiffness With a Simple Symmetric Parallel Mechanism
Authors: Huang Shuguang , Schimmels Joseph M.
Published: March 2011

This paper presents a new method for the realization of a planar compliant behavior with an elastic mechanism. The mechanisms considered are parallel mechanisms with symmetric geometry. We show that any planar stiffness matrix can be realized using a parallel mechanism with four line springs connected symmetrically. Among the four springs, two are identical parallel springs equidistant from the stiffness center, and the other two identical springs intersect at the stiffness center. A synthesis procedure is presented.
Best for Whom? Changing Design for Creative Customers
Authors: Fukuda Shuichi
Published: March 2011

Our traditional design has been producer-centric. But to respond to the frequent and extensive changes and increasing diversification, we have to change our design to user-centric. But it is not a straightforward extension and just listening to the voice of the customer is not enough. Value is defined as value = performance/cost, but performance has been interpreted in the current design solely as functions of a final product and all other factors such as manufacturing are considered as cost. This framework has been effective until recently because there has been asymmetry of information between the producer and the customer. As the producer had a greater amount of information, they only had to produce a product which they think best and it really satisfied the customer who needed a product. The 20th century was the age of products. But as we approached the 21st century, we entered information society and sometimes the customer knows more than the producer. Thus, such a one way flow of development to fill the information (water level) gap doe not work any more, because the gap is quickly disappearing. The difference was evaluated as value in the traditional design and it meant profit for the producer. Therefore, a new approach to create value is called for. One solution is to raise the water level together by the producer and the customer so that the level increase serves for profit for the producer and for the true value for the customer. In order to achieve this goal, we have to identify what is the true value for the customer. We have to step outside of our traditional notion of value being functions of a final product. What is the true value for the customer? It is customers’ satisfaction. Then, how can we satisfy our customers. This paper points out if we note that our customers are very active and creative, we can provide satisfaction to them by getting them involved in the whole process of product development. Then our customers can enjoy not only product experience but also process experience, which will satisfy their needs for self actualization and challenge, i.e., their highest human needs.
A Step Toward Risk Mitigation During Conceptual Product Design: Component Selection for Risk Reduction
Authors: Krus Daniel , Grantham Katie
Published: March 2011

The objective of this paper is to introduce a method that will mitigate product risks during the conceptual design phase by identifying design variables that affect product failures. By using this comprehensive, step-by-step process that combines existing techniques in a new way, designers can begin with a simple Functional Model and emerge from the conceptual design phase with specific components selected with many risks already mitigated. The Risk in Early Design (RED) method plays a significant role in identifying failure modes by functions, and these modes are then analyzed through modeling equations or lifespan analyses, in such a manner that emphasizes variables under the designers’ control. With the valuable insight this method provides, informed decisions can be made early in the process, thereby eliminating costly changes later on.
A Study on Situated Cognition: Product Dissection’s Effect on Redesign Activities
Authors: Grantham Katie , Okudan Gu¨l , Simpson Timothy W. , Ashour Omar
Published: March 2011

Situation cognition theory describes the context of a learning activity’s effect on learner’s cognition. In this paper, we use situated cognition theory to examine the effect of product dissection on product redesign activities. Two research questions were addressed: 1) Does situated cognition, in the form of product dissection, improve product functionality during redesign exercise?, and 2) Does situation cognition, again in the form of product dissection, affect the creativity of product redesigns? In this study, three sections of first year students in two different locations — The Pennsylvania State University (Penn State) and Missouri University of Science and Technology (S&T) — performed product redesign using either an electric toothbrush or a coffee maker. The redesigned products have been analyzed with respect to both depth (detail level) and creativity.
On a Data and Requirements Driven Multi-Scale Framework Linking Performance to Materials
Authors: Michopoulos John G. , Lambrakos Samuel G. , Iliopoulos Athanasios
Published: March 2011

The initial progress towards the design and development of a framework for automating the process of integrating experimental data with stakeholder specifications describing usability requirements, along with multiscale models for tailoring material and structural behavior characteristics is reported in the present paper. The proposed framework consists of a layered architecture that is comprised of three main layers. The first layer involves the computational infrastructure that implements the low level computational container that encompasses the computational codes that enable the modeling of the forward problem for various physical problems at specific time and length scales. The second layer of the framework implements the cascaded and hierarchical implementation of the inverse problem in terms of a composition of discrete event system and differential equation system specifications. The third element of the proposed architecture utilizes Category theory abstractions and their computational implementations to provide the necessary infrastructure for automating the process of developing synthetic specifications driven from experimental data and performance requirements related to the design and use of material and structural systems.
Optimal Design of a Micro Series Elastic Actuator
Authors: Tokatli Ozan , Patoglu Volkan
Published: March 2011

We propose using series elastic actuation (SEA) in micro mechanical devices to achieve precise control of the interaction forces. Using μSEA for force control removes the need for high-precision force sensors/actuators and allows for accurate force control through simple position control of the deflection of a compliant coupling element. Since the performance of a μSEA is highly dependent on the design of this compliant coupling element, we employ a design optimization framework to design this element. In particular, we propose a compliant, under-actuated half-pantograph mechanism as a feasible kinematic structure for this coupling element. Then, we consider multiple design objectives to optimize the performance of this compliant mechanism through dimensional synthesis, formulating an optimization problem to study the trade-offs between these design criteria. We optimize the directional manipulability of the mechanism, simultaneously with its task space stiffness, using a Pareto-front based framework. We select an optimal design by studying solutions on the Pareto-front curve and considering the linearity of the stiffness along the actuation direction as a secondary design criteria. The optimized mechanism possesses high manipulability and low stiffness along the movement direction of the actuator; hence, achieves a large stroke with high force resolution. At the same time, the mechanism has low manipulability and high stiffness along the direction perpendicular to the actuator motion, ensuring good disturbance rejection characteristics. We model the behavior of this compliant mechanism and utilize this model to synthesize a controller for μSEA to study its dynamic response. Simulated closed loop performance of the μSEA with optimized coupling element indicates that force references can be tracked without significant overshoot and with low tracking error (about 1.1%) even for periodic reference signals.
Leveraging Production Waste Streams: Enablers of Successful By-Product Exchange—An Exploratory Study
Authors: Gyles Trevor , Mruthyunjaya Alicia , Sanchez Franley , Valentino Jerry , Esterman Marcos
Published: March 2011

As the topic of sustainability continues to gain momentum, companies are seeking ways to integrate environmental solutions into their product development process. Decisions made throughout the product development process affect the sustainability of the product from raw material extraction, to production process impacts, to end of life disposal. One such impact is the generation of waste by-products. By utilizing waste as raw materials, companies can continue to cycle technical and biological nutrients thus minimizing the scatter of waste to the natural environment. The focus of this research is to explore the enablers and barriers to utilizing waste streams as raw materials. Using a qualitative approach, nine different organizations from four companies crossing over multiple industries are studied. Key characteristics of production waste that enable successful by-product exchanges are identified, as well as the role the product development process needs to play in creating value from exchanges.
Design for Assembly Line Performance: The Link Between DFA Metrics and Assembly Line Performance Metrics
Authors: Esterman Marcos , Kamath Krishna
Published: March 2011

While Design for Assembly (DFA) has been a useful design tool, it is not explicitly linked to actual manufacturing line performance. The motivation for this research came from the desire to link DFA directly to line balance and cycle time performance. The natural question that arose was whether these issues could be considered at the design stage by using the metrics that are derived from a DFA analysis. It is known that the time required to assemble a product can be estimated from both a DFA analysis and from a manufacturing analysis. This work links these two analysis methods so that the manufacturing parameters can be estimated and used to guide the design of a product. Starting with a DFA analysis, the minimum number of workstations needed to balance the line that will maintain the production rate (takt time) and precedence constraints is determined. Then the precedence constraints are systematically relaxed in order to generate measures on a component-by-component basis as to the impact it could have on reducing cycle time and improving line balancing performance. These measures, coupled with an understanding of precedence types, are used to identify design improvements to a product. To illustrate how product designer can consider assembly line performance issues during the design stage of the product, the methodology has been applied to an ABS brake assembly.
Function Impact Matrix for Sustainable Concept Generation: A Designer’s Perspective
Authors: Bernstein William Z. , Ramanujan Devarajan , Devanathan Srikanth , Zhao Fu , Sutherland John , Ramani Karthik
Published: March 2011

Reducing the environmental effects of products has become a significant focus of corporate strategies. As a result, easy-to-use ecodesign tools that can be implemented during the early design stage are essential for corporations to gain a competitive advantage in product development. A novel eco-design method, the function impact matrix (FIM), is being developed as a tool to enable the development and evaluation of design concepts by correlating environmental impacts with product functions. This paper aims to illustrate the efficacy and relative ease of use of the FIM. Understanding designers’ interactions with visual tools and cognitive load analysis of designers can provide new insight that aids in the development of easy-to-use ecodesign tools. In this pilot study, design engineers with varying levels of experience and self-perceived eco-design knowledge are asked to redesign an alarm clock under four different design scenarios: 1) using no eco-design tools, 2) using the LiDS wheel and an ecodesign checklist, 3) raw life cycle assessment (LCA) data and 4) the function impact matrix. Surveying the designers reveals that the function impact method carried the highest overall rank compared to the other ecodesign tools with regard to ease of use, quality of data, ability for identifying redesign opportunities, and overall effectiveness. As suggested by the designers, a combination of a modified LiDS wheel with the FIM would lead to a helpful tool for sustainable concept generation.
Morton Effect Induced Synchronous Instability in Mid-Span Rotor-Bearing Systems: Part 1—Mechanism Study
Authors: Guo Zenglin , Kirk Gordon
Published: March 2011

The Morton Effect in the rotor–bearing systems may lead to an unstable operation. In Part 1, the mechanism of the Morton Effect induced thermal instability in the mid-span rotor systems has been studied. First, the equivalent thermal induced imbalance is introduced and its magnitude and directions are assumed, to represent the viscous thermal effect on the rotor systems. Then, the simplified rotor and bearing models are adopted for the derivation of analytical expressions. The results show that there exists a threshold of instability due to the Morton Effect in the mid-span rotors. Based on the assumptions of linear isotopic bearing supports, this threshold speed takes a simple form, which is determined by the support stiffness and the introduced equivalent coefficient of thermal effect, for the rigid or elastic systems with the thermal imbalance acting in the same direction as the response displacement. The threshold of instability has also been obtained for the system with the thermal imbalance acting perpendicular to the direction of response displacement, where the supporting damping plays a role. For a perspective view of the system stability, a stability map for the damped rigid mid-span rotors with the thermal imbalance having arbitrary phase difference has been generated. It shows that the stable operating regions of the system are bounded by two curves of threshold of instability, named the first and second threshold speeds of instability, respectively. The Morton Effect induced instability thresholds are actually affected by both the magnitude and relative phase of the thermal imbalance. The mechanism of the Morton Effect induced thermal instability of mid-span rotors supported by linear isotropic bearings can be explained through the fact that the Morton Effect introduces either negative stiffness or negative cross-coupled stiffness. In addition, the Morton Effect also has a comprehensive impact on both the amplitude and phase lag of the steady-state unbalance response. It may shift both curves in a manner dependent on the relative magnitude and direction of the thermal imbalance.
Morton Effect Induced Synchronous Instability in Mid-Span Rotor-Bearing Systems: Part 2—Models and Simulations
Authors: Guo Zenglin , Kirk Gordon
Published: March 2011

The mechanism of the Morton Effect induced synchronous instability has been discussed in Part 1, using an assumption of isotropic linear bearings. The second part of the current study will now focus on the more realistic systems, mid-span rotors supported by the hydrodynamic journal bearings. First, the models to calculate the thermal bending of the shaft and the temperature distribution across the journal surface are established. This can be used to calculate the equivalent thermal imbalance. The calculations of the temperature difference and its equivalent thermal imbalance using hydrodynamic plain journal bearing models are conducted and discussed with the comparison to the analytical results obtained in Part 1. It shows that the thermal imbalance induced by the Morton Effect may increase to the level of the mechanical imbalance and then its influence on the system stability should be included. The suggested thermal bending model also partially explain that the mid-span rotors are less liable to be influenced by the Morton Effect induced instability than are the overhung configurations, because of the restraining effect between two supports. Finally, a symmetric mid-span rotor–hydrodynamic journal bearing system is calculated to show its stability performance. The results show the inclusion of the Morton Effect may lead to an unstable operation of the system. Considering the existence of the oil film self-induced vibration due to the dynamic characteristics of fluid film bearings, the Morton Effect may make a further negative impact on the stability of the system. The simulation results of the unbalance response show that the Morton Effect changes the shapes of the whirling orbits and makes them no longer be the standard elliptical orbits around the static equilibriums.
A Preliminary Study on Systems Health Management and the Assessment of Future Research Requirements: A Safety Perspective
Authors: Kurtoglu Tolga , Leone Karen M. , Sandifer Carl E. , Reveley Mary S. , Thomas Megan A. , Venti Mike
Published: March 2011

A health management (HM) system is responsible for information gathering about a system’s health and corresponding decision-making. HM systems are typically used to identify any degradation in performance that may affect safety or successful operations of a system. Effective long term development of successful health management solutions requires an improved understanding of the relationship between potential adverse events that may happen during flight, and validated tools, technologies, and techniques developed for mitigating their negative effects on system safety and functionality. This paper presents a study on the assessment of future requirements for systems health management technologies and related research areas. The gist of the paper is the mapping between systems health management technologies and damage conditions extracted from a study of aircraft accident and incident data. The goal of the study is to identify key research areas in systems health management and to recommend specific technology needs to support the development of integrated system health management tools, technologies, and techniques that will address safety related challenges facing current and future aircraft systems.
Ten Tips for Energy-Efficient Air-Conditioned Buildings
Authors: Khalil Essam E.
Published: March 2011

The Developing communities in their path for rapid development is endeavoring to make all necessary and appropriate measures to enhance the efficiency of energy utilization and increase the beneficiation of the energy resources. The energy production, transmission, distribution and utilization efficiency becomes a vital factor and measure of national development. Governmental organizations were established earlier to be responsible for energy planning and efficient utilization, information dissemination and capacity building as well as devising the necessary codes and standards. Energy rationalization and audit exercises were developed and monitored by Governmental authorities, Universities and Research centers through the past two decades with a definitive positive energy reduction and beneficiation. The development of the relevant codes of practice and giving hints and tips to energy managers on how to effectively reduce their energy bill is forcibly underway.
Tips on Design of Energy Efficient Hospitals Air Conditioning Systems
Authors: Khalil Essam E.
Published: March 2011

Energy Efficiency and Indoor Air Quality in the healthcare applications and particularly in surgical operating theatres are important features in modernized designs. The various reasons for deviation from obtaining optimum IAQ and energy efficient buildings are listed. The air conditioning systems serving the operating rooms require careful design to minimize the concentration of airborne organisms. Numerical approach is an appropriate tool to be utilized to adequately identify the airflow patterns temperatures and relative humidity distributions and hence energy efficient designs.
Design of a Generic Zero Stiffness Compliant Joint
Authors: Morsch Femke M. , Herder Just L.
Published: March 2011

The objective of this paper is to design a generic zero stiffness compliant joint. This compliant joint could be used as a generic construction element in a compliant mechanism. To avoid the spring-back behavior of conventional compliant joints, the principle of static balancing is applied, implying that for each position of the joint the total potential energy should be constant. To this end, a conventional balanced mechanism, consisting of two pivoted bodies which are balanced with two zero-free-length springs, is taken as an initial concept. The joint is replaced by a compliant cross-axis flexural pivot and each spring is replaced by a pair of compliant leaf springs. For both parts an analytic model was implemented and a configuration with the lowest energy fluctuation was found through optimization. A FEA model was used to verify the analytic model of the optimized design. A prototype was manufactured and tested. Both the FEA model and the experiment confirm the reduction of the needed moment to rotate the compliant joint. The experiment shows the balanced compliant joint is not completely balanced but the moment required to rotate the joint is reduced by 70%. Thus, a statically balanced compliant generic joint element was designed which bears great promise in designing statically balanced compliant mechanisms and making this accessible to any designer.
An Introduction to Rational Design Theory
Authors: Thompson Stephanie C. , Paredis Christiaan J. J.
Published: March 2011

Design theories provide theoretical foundation for design and can lead to insights that improve the practice of design. From a theoretical perspective, existing design theories have some major limitations that limit the insights that can be gained and restrict their applicability in practice. These limitations include the treatment of uncertainty and the lack of interaction of concerns regarding the designed artifact and the design process. In this paper, a new design theory is introduced that explicitly includes uncertainty considerations and enables quantitative tradeoffs between the utility of the product and the process. This new theory is inspired by decision theory and expands upon the traditional product-centric perspective of decision-based design; the new theory is therefore termed Rational Design Theory (RDT). RDT combines a decision-theory-inspired descriptive model of artifact design decisions with a normative perspective for design process decisions. This theory provides new insights into the process of design that can inspire improved design methods. Furthermore, RDT provides a quantitative framework for comparing the relative performance of different design processes.
Modal Control of Underactuated Systems
Authors: Quinn D. Dane , Mallela Vineel
Published: March 2011

This work addresses the modal control of underactuated mechanical systems, whereby the number of actuators is less than the degree-of-freedom of the underlying mechanical system. The performance of the control system depends on the structure of the feedback gain matrix, that is, the coupling between sensors and actuators. This coupling is often not arbitrary, but the topology of the sensor-actuator network can be a fixed constraint of the control system. This work examines the influence of this structure on the performance of the overlying control system.