bluuebunny/crossref_metadata_2025 huggingface dataset:
Optimal Design of a Simplified Morphing Blade for Fixed-Speed Horizontal Axis Wind Turbines
Authors: Wang Weijun , Caro Stéphane , Bennis Fouad , Salinas Mejia Oscar Roberto
Published: September 2013

The aim of designing the wind turbine blades is to improve the power capture ability. Since the rotor control technology is currently limited to controlling the rotor rotational speed and the pitch of the blades, an increasing concern has been given to the morphing blades. In this paper, a simplified morphing blade is introduced, which has a linear twisted distribution along the span and its shape can be controlled by adjusting the root twisted angle and the tip twisted angle of the blade. Moreover, to evaluate the performances of the wind turbine blades, a numerical code based on the blade element momentum theory is developed and validated. The blade of the NREL Phase VI wind turbine is taken as a reference blade, and the optimization problems associated with the morphing blade and pitch control blade are both formulated. The optimal results show that the morphing blade gives better results than the pitch control blade in terms of produced power. Under the assumption that in a given site, the annual average wind speed is known and the wind speed follows the Rayleigh distribution, we can evaluate the annual energy produced by these three blade types. While the annual average wind speed varies from 5 m/s to 15 m/s, the results show that the optimal morphing blade can increase 23.9 percent to 71.4 percent in annual energy production while the optimal pitch control blade can increase 22.5 percent to 67.4 percent in annual energy production, over the existing twisted pitch fixed blade.
Correlation of Atomic Force Microscopy Tapping Forces to Mechanical Properties of Lipid Membranes
Authors: Shamitko-Klingensmith Nicole , Wambaugh Kelley M. , Burke Kathleen A. , Magnone George J. , Legleiter Justin
Published: September 2013

There is considerable interest in measuring, with nanoscale spatial resolution, the physical properties of lipid membranes because of their role in the physiology of living systems. Due to its ability to nondestructively image surfaces in solution, tapping mode atomic force microscopy (TMAFM) has proven to be a useful technique for imaging lipid membranes. However, further information concerning the mechanical properties of surfaces is contained within the time-resolved tip/sample force interactions. The tapping forces can be recovered by taking the second derivative of the cantilever deflection signal and scaling by the effective mass of the cantilever; this technique is referred to as scanning probe acceleration microscopy. Herein, we describe how the maximum and minimum tapping forces change with surface mechanical properties. Furthermore, we demonstrate how these changes can be used to measure mechanical changes in lipid membranes containing cholesterol.
Design of Mechanical Structures Considering Harmonic Loads Using Level Set-Based Topology Optimization
Authors: Yamada Takayuki , Matsumoto Toshiro , Nishiwaki Shinji
Published: September 2013

This paper presents an optimum design method for mechanical structures considering harmonic loads using a level set-based topology optimization method and the Finite Element Method (FEM). First, we briefly discuss the level set-based topology optimization method. Second, a topology optimization problem is formulated for a dynamic elastic design problem using level set boundary expressions. The objective functional is set to minimize the displacement at specific boundaries. Based on this formulation, the topological sensitivities of the objective functional are derived. Next, a topology optimization algorithm is proposed that uses the FEM to solve the equilibrium and adjoint equations, and when updating the level set function. Finally, several numerical examples are provided to confirm the validity and utility of the proposed method.
A Comprehensive Elliptic Integral Solution to the Large Deflection Problems of Cantilever Beams in Compliant Mechanisms
Authors: Zhang Aimei , Chen Guimin
Published: September 2013

The elliptic integral solution is often considered as the most accurate method for analyzing large deflections of cantilever beams in compliant mechanisms. In this paper, by explicitly including the number of inflection points (m) and the sign of the end-moment load (SM) in the derivation, a comprehensive solution based on the elliptic integrals is proposed for solving the large deflection problems. The comprehensive solution is capable of solving large deflections of cantilever beams subject to any kind of load cases and of any kind of deflected modes. A few deflected configurations of complex modes solved by the comprehensive solution are presented and discussed. The use of the comprehensive solution in analyzing compliant mechanisms is also demonstrated by a few case studies.
Using Fault Propagation Analyses for Early Elimination of Unreliable Design Alternatives of Complex Cyber-Physical Systems
Authors: Papakonstantinou Nikolaos , Sierla Seppo , Tumer Irem Y. , Jensen David C.
Published: September 2013

The Functional Failure Identification and Propagation (FFIP) framework has been proposed in prior work to study the reliability of early phase designs of complex systems. For the specified functionality, a model of mechanical, electrical and software components has been defined to support simulation and discovery of fault propagation paths. The advantage of this approach has been the possibility to identify unreliable designs before high cost design commitments have been made. However, a weakness is that the results are specific to the component model that is created for the purpose of running the FFIP simulations; it is unclear how the results would change if different modeling choices would have been made. Further, the usefulness of the method in design has been limited to evaluating reliability rather than actively finding more robust design alternatives. In order to address these weaknesses, the FFIP component model needs to incorporate a capability to describe design alternatives. The feature modeling syntax and semantics, which has been successfully used by software engineers to describe customer variations in product lines, is applied here to specify alternative mechanical, electrical and software features of a cyber-physical system. In the concept phase, all plausible design alternatives are described with a feature model. FFIP analyses can be performed for each valid configuration of this model, and all alternatives that are found unreliable are removed. The result is a restricted feature model, comprising significantly fewer design alternatives, that is delivered as source information for the detailed design phase. A toolchain for performing these analyses is presented, integrating open source feature modeling and configuration tools to the FFIP environment. The methodology is illustrated with a case study from boiling water nuclear reactor design.
The Generation of Machining Process Plans Using a Haptic Virtual Reality System
Authors: Fletcher C. A. , Ritchie J. M. , Lim T.
Published: September 2013

Computer Aided Process Planning (CAPP) links the design and manufacture of a machined product defining how the product itself will be manufactured. Decisions made during this phase can have a significant impact on product cost, quality and build time; therefore, it is important that process planners have intuitive tools to aid them in effectively creating process plans. However, in spite of being a strong research area, the actual application of CAPP systems in industry is limited and new modern 3D digital tools in this area have not been researched to any real degree.

Traditional process planning is carried out either manually or via a CAPP interface and, from this activity, a set of instructions are generated for the shop floor. However, these CAPP processes can be time consuming and subject to inconsistencies. Current research seeks to automate the generation of work instructions by using previous designs and/or artificial intelligence. However, due to the complexity of manufacturing a wide range of products, the limited range of tools available and differing skills of the workforce, it is difficult to reach a generic solution for practical application.

The novel pilot study given in this paper presents one of the first pieces of research comparing and contrasting a traditional manual approach to machined part process planning with an alternative haptic virtual environment. Within this, an operator can simulate the machining of a simple part using a virtual drilling and milling process via a haptic routing interface. All of the operator input is logged in the background with the system automatically generating shop floor instructions from this log file.

Findings show that users found the virtual system to be more intuitive and required less mental workload than traditional manual methods. Also their perceptions for the future were that they would need less support for learning and would progress to final planning solutions more quickly.
Contact Kinematics in the Roller Screw Mechanism
Authors: Jones Matthew H. , Velinsky Steven A.
Published: September 2013

This paper investigates the nature of the contact between the load transferring surfaces in the roller screw mechanism, i.e., between the screw and roller threads and between the nut and roller threads. The analysis is applied to both planetary roller screws and recirculating roller screws. Prior work has neglected to take a fundamental approach toward understanding the mechanics of the contact between these components, and as a consequence, detailed analysis of aspects such as contact mechanics, friction, lubrication, and wear are not carried out correctly. Accordingly, in this paper, the principle of conjugate surfaces is used to establish contact at the screw-roller and nut-roller interfaces. The in-plane angles to the contact points are derived and it is shown that for the screw-roller interface, the contact point cannot lie on the bodies’ line of centers as has been the assumption in previous papers. Then, based on the curved profile of the roller thread, the radii of contact on the roller, screw, and nut bodies are also derived. Knowledge of the contact point locations is necessary to understand the interaction forces between the key components of the roller screw mechanism. In addition, accurate estimates of the radii of contact are necessary for minimizing the phenomenon of roller migration, a condition that can cause binding between components and eventually lead to the destruction of the mechanism. Last, the principal radii of curvature at the contact points and the angle between the principal axes are derived. These are essential for further development of the contact mechanics, such as the surface stresses, deformations, and consideration of wear.
Subcritical Twice-Running-Speed Vibrations of a Non-Ideal Rotor-Bearing-System: Simulation and Experiments
Authors: Heikkinen Janne E. , Sopanen Jussi T. , Mikkola Aki M.
Published: September 2013

Subcritical twice-running-speed resonances of a paper machine tube roll are studied in this paper. Resonances arise partly from the non-idealities of the rotor and partly from the non-idealities of the bearings. Resonances are affecting the quality of end product and therefore have to be studied precisely. The complex rotor-bearing system is modeled by using a flexible multibody simulation approach. Non-idealities of the rotor-bearing system are measured from the existing structure under investigation and the parameters of the real structure are emulated as accurately as possible in the simulation model. The simulation model is verified using the results from experimental modal analysis and the measurement results for the subcritical twice-running-speed response of the roll. The inertia modeling of the flexible rotor is also studied. It is found that inertia coupling between the rigid body rotation and body deformation must be included into analysis in order to achieve accurate results.
Non-Linear Generalized Maxwell Model for Dynamic Characterization of Viscoelastic Components and Parametric Identification Techniques
Authors: Jrad Hanen , Dion Jean Luc , Renaud Franck , Tawfiq Imad , Haddar Mohamed
Published: September 2013

Viscoelastic components are incorporated into automobile and aerospace structures system in order to damp mechanical vibrations. Viscoelastic components are a key element in designing desired dynamic behaviour of mechanical systems. Viscoelastic components dynamic characteristics are often very complex, due to the dependence of its response on several variables, such as frequency, amplitude, preload, and temperature. These dependencies can be critical in capturing the mechanical proprieties and so non linear dynamical behaviour may appear. Assuming that non linearities are due to non linear elasticity, the non linear Generalized Maxwell Model (GMM) is proposed to characterize dynamics of viscoelastic components. Parameters of GMM are identified from Dynamic Mechanical Analysis (DMA) tests for different excitation frequencies. A particular result from identification is that the non linear stiffness is dependent upon displacement amplitude and static displacement under static preload. The significance of this result is that the non linear dynamics of the viscoelastic component can be represented by a simple analytical model capable to produce accurate results. Comparison between measurements and simulations of dynamic stiffness of viscoelastic component has been carried on.
Convex Decomposition of 3D Solid Models for Automated Manufacturing Process Planning Applications
Authors: Eftekharian Ata A. , Campbell Matthew I.
Published: September 2013

A new method of decomposing 3D solid models for use in automated manufacturing process planning applications is presented in this paper. The resulting algorithm, which is implemented and interacts with a larger suite of planning tools, is based on dividing complex volumes into convex sub-volumes. In order to ensure that the resulting convex sub-volumes are compact and feasible for machining operations, a set of heuristics are developed to categorize, order, and determine splitting directions of the concave edges. Each of the resulting convex sub-volumes represents material that is to be removed from the bounding-box to create the intended work-piece. The set of sub-volumes represents a compound solid (i.e. decomposed solid) that is converted into graph of boundary representation (B-rep) primitives and is reasoned about in a subsequent search process. The algorithm has been implemented and tested on a variety of solid models resembling real automotive parts, and results show the effectiveness and efficiency of the algorithm.
An Adaptive Weighting Strategy for Multi-Load Topology Optimization
Authors: Suresh Krishnan , Ramani Anand , Kaushik Anshul
Published: September 2013

In this paper, we consider topology optimization of continuum structures subject to multiple loads. The objective is to minimize mass, while satisfying maximum displacement constraints at the points of load-application.

The classic method of including displacement constraints is through penalization of the objective function. Here, we propose an alternate method that relies on the concept of topological sensitivity. The proposed method generalizes the recently proposed single-load PareTO method by the first author. For multi-load problems, the topological sensitivity fields for each of the load-cases are computed, and then combined through weighting functions that continuously adapt to satisfy the constraints. Different weighting functions are considered, and compared through numerical experiments.
Bipedal Walking Robot Driven by Elastic Cables
Authors: Kljuno Elvedin , Williams Robert L. , Zhu Jim
Published: September 2013

This paper presents a design concept and analysis of a bipedal walking robot with a novel type of actuation using elastic cables. Each leg has 6-dof, the trunk has 3-dof, and each arm has 1-shoulder-dof. Conventional walking robots consist of joint-attached drives at revolute joints. This yields relatively heavy legs and arms with high moments of inertia, which makes balancing robot dynamic walking difficult due to the high inertial forces of distal segments.

The cable-based actuation system is designed for the most kinetically-active biped segments, such as lower legs. These consist of DC motors located on the trunk, elastic cables (with serially-connected springs) and cable routing with specially-designed pulleys. Since the trunk segment accelerations are significantly lower than the leg segments accelerations, it is expected that the overall energy required by the cable-actuated robot is significantly lower than the energy input to a directly-actuated biped.

Another novelty in the biped actuation system design is the use of elastic rather than non-elastic cables, for two reasons: smoothing out the sharp impulses due to the foot-ground collision and reduction of the number of motors to actuate each joint. Non-elastic cable-based drives require each cable to be pulled by a separate motor, which would double the number of motors and increase the weight. This problem can be solved using elastic cables and specially-shaped pulleys to reduce the number of motors with a slight increase in controller complexity.

The bipedal walking robot architecture with cable drives mimics the human body architecture, where the hip joint is a 3-dof spherical joint, 1-dof knee joint, and 2-dof ankle joint. The architecture is more compact compared to the conventional joint attached drive architecture, wherein all revolute joints are separated.

Based on the kinematic and dynamic analysis of the robot, a controller is designed and the perturbation robustness tested. A feedback linearization controller design is used, requiring system dynamics knowledge. Steps toward hardware implementation have been made, since we have implemented an elastic cable actuation system on a robotic cat prior to the concept design for the bipedal robot. The difficulties are discussed, including future plans for improvements and hardware testing.
Systematic Ideation Effectiveness Study of TRIZ
Authors: Vargas Hernandez Noe , Schmidt Linda C. , Okudan Gül E.
Published: September 2013

The objective of this paper is to present experimental results of a specific ideation method: TRIZ. Our hypothesis is that TRIZ improves the creativity of subjects using it as observed in the produced design outcomes. The experiments were conducted simultaneously at two institutions: University of Texas at El Paso and University of Maryland. The same ideation task was used at both institutions, a redesign of a traffic light that uses Light-emitting Diodes (LED) instead of incandescent bulbs challenging the designer subject with the issue of snow accumulation since LED’s do not melt the snow. The assessment was performed on the outcome (i.e., ideas generated) using quantity, novelty and variety as metrics. Numerical results show that using TRIZ improved the Novelty and Variety of the concepts generated by students at both institutions.
Magneto-Rheological (MR) Damper Modeling for Semi-Active Control Without Force Feedback
Authors: Strydom Anria , Els Pieter S. , Kaul Sudhir
Published: September 2013

Ride comfort and handling characteristics are two important aspects of vehicle dynamics that generally require contrasting suspension settings. Different damper settings of the suspension system are required in order to meet these conflicting requirements. A magneto-rheological (MR) damper allows variable suspension settings to achieve enhanced ride comfort as well as handling characteristics by providing adaptable damping. Implementation of semi-active control requires an accurate MR damper model and online identification of model parameters. However, modeling a MR damper for a wide range of input conditions is challenging, especially when there are constraints on necessary measurements that are required for modeling. Although the available literature proposes various parametric models, many of these models are computationally expensive and are not viable for online identification. This paper presents a non-parametric model as well as a recursive model to predict the damping force of a MR damper in order to implement a semi-active control algorithm on an off-road vehicle. The results of the two models are compared to a conventional parametric model. The recursive model is used to demonstrate the significance of including the measured damping force in the model. Whereas the availability of the measured damping force yields a reasonably accurate model, the lack of measured damping force significantly impairs the recursive model.
Automated Parametric Design Synthesis Using Graph Grammars and Constraint Solving
Authors: Münzer Clemens , Shea Kristina , Helms Bergen
Published: September 2013

Computational design synthesis aims to support human designers throughout the design process. However, most approaches to date are limited to narrow parts of this process. The approach presented in this paper aims to respond to the need for a method that covers not only single aspects of the design process, but the whole design process from requirements to a dimensioned product concept, i.e. product architecture and related parameters. A generic approach is presented that covers requirements engineering, graph grammar-based concept architecture synthesis and automated parameterization of components based on constraint solving. Requirements are elaborated and divided into different categories. Procedures to treat each category of requirement are introduced to provide the initial state for the graph grammar-based concept synthesis. After finishing the automated synthesis based on generic and problem-specific rules, valid solutions for the resulting product concept parameterization are automatically created by setting up and solving a constraint satisfaction problem. Finally, the method is validated through the synthesis of automotive powertrains. This research goes beyond prior work in the field as it provides a continuous and generic approach starting with product requirements and ending with a valid, parameterized product concept.
Kinematics and Dynamics of a Planar Tensegrity Mechanism for Ocean Wave Energy Harvesting
Authors: Vasquez Rafael E. , Correa Julio C. , Crane Carl D.
Published: September 2013

Tensegrity systems have been used in several disciplines such as architecture, biology, aerospace, mechanics and robotics during the last fifty years. However, just a few references in literature have stated the possibility of using tensegrity systems in ocean or energy-related applications. This work addresses the kinematic and dynamic analyses of a planar tensegrity mechanism for ocean wave energy harvesting. A planar tensegrity mechanism is proposed based on a planar morphology known as “X-frame” that was developed by Kenneth Snelson in 1960s. A geometric approach is used to solve the forward and reverse displacement problems. The theory of screws is used to perform the forward and reverse velocity analyses of the device. The Lagrangian approach is used to deduce the equations of motion considering the interaction between the mechanism and a linear model of ocean waves. The result shows that tensegrity systems could play an important role in the expansion of clean energy technologies that help the world’s sustainable development.
Non-Linear Frequency Response of Atomic Force Microscope Cantilevers at the Solid-Liquid Interface
Authors: Kiracofe Daniel R. , Raman Arvind
Published: September 2013

One significant advantage of atomic force microscopy (AFM) over other microscopy methods is its ability to characterize surfaces in liquid environments. However, operation in liquid is complicated by the large hydrodynamic loading, which leads to low quality factors, and in turn leads to many changes in the dynamics as opposed to air/vacuum environments. A thorough understanding of the dynamics is necessary for properly interpreting data from experiments. In this work, we study the non-linear dynamics of AFM micro-cantilevers interacting with hard surfaces in liquids. In comparison to prior works that have mostly examined the dynamics at a single drive frequency, we examine the full nonlinear frequency response. Two important results are highlighted. First, in addition to the primary resonance, there are also superharmonic resonances, which can distort tapping mode approach curves. Secondly, we point out that the layering (hydration forces) of liquid molecules at the solid-liquid interface, traditionally detected using small amplitude (linear) AFM, in fact has a significant effect on the nonlinear response. These results are shown by experiments and examined analytically. The effects of parameters such as cantilever stiffness and quality factors are studied using numerical simulation.
Opportunities and Barriers to Straw Construction
Authors: White Caroline Meyer , Howard Thomas J. , Lenau Torben A.
Published: September 2013

During the past decades the building industry has had a great focus on energy consumption during the use phase of a building, but currently a more holistic view of the entire lifecycle of a building is starting to emerge. With this follows a greater interest in which building materials and techniques of construction are considered. At the same time the request for a living environment free from toxins and allergenic substances, providing the basis for stress-free living and working conditions is increasingly demanded by clients for newly built homes. Since straw built houses supply a possible solution for these demands, while also offering the opportunity for very financially competitive solutions, it is of interest to determine their appropriateness in the design phase of a building. Through a study carried out by means of a review of the current state of the-art literature on straw construction, and a series of qualitative interviews with a variety of stakeholders from previous straw build housing projects, results were gathered to find the most influential motives, barriers and considerations for straw build housing construction. Based on this empirical data, a design guide has been produced to support communication between clients and the consultants and facilitate the straw build design and decision making process. The intended audiences for the design guide are clients of small scale construction projects, architects, engineers, builders of straw construction, homeowner-builders and entrepreneurs considering the use of, straw construction. The aim of the design guide is both to acting as inspiration for the clients by outlining the benefits, determine whether straw construction would be suitable for a given project, and if so, to suggest a specific approach to the design and development of a successful straw-build project, running through the main considerations and pitfalls. The main concluded difference between straw build and more conventional building techniques is not that there are more difficulties or uncertainties related to straw build, but that they are less commonly dealt with and thus perceived as a barrier to straw build, rather than simply a problem of a general character.
Behaviors of Bio-Functionalized Magnetic Nanoparticle Clusters in a Rotating Magnetic Field
Authors: Hong Chin-Yih , Lai Ji-Ching , Tang Chia-Chung
Published: September 2013

Manipulation of magnetic nanoparticles has many applications in several fields and the behaviors of magnetic nanoparticles subjected to rotating or alternating magnetic fields attracted more attention from biomedical applications. In an aqueous solution containing bio-functionalized magnetic nanoparticles, due to the interaction between biomolecules, these nanoparticles agglomerate and form clusters with various sizes and shapes. In this study, the behaviors of magnetic nanoparticle clusters in an aqueous solution under rotating magnetic fields were investigated. Due to the interaction between the rotating magnetic field and the net magnetic dipole moment, the clusters were subjected to forced vibration. Two motion modes of clusters were observed as the magnetic field rotated. These two modes are rotation and oscillation. The diameters of the magnetic clusters with rotational or oscillational motions were measured. A critical diameter range of magnetic cluster was defined and the range is between 10.21 μm and 6.17 μm that could be used to distinguish rotation and oscillation of clusters.
A Fundamental Study on Dynamic Contact Behavior of an Ultrasonic Motor (Coexistence of Stick and Slip Contact Zone)
Authors: Ohnishi Takafumi , Nakayama Tomoaki , Yamashita Kiyotaka , Takatsuka Kohro , Akuto Tsuneo , Yabuno Hiroshi
Published: September 2013

We discuss the dynamic complex contact behavior between the stator and the liner that sticks to the rotor of an ultrasonic motor. An ultrasonic motor is powered by the vibration of the stator and operated by a frictional force between them. Therefore, it is important to examine the dynamic mechanism of the contact behavior to improve the energy efficiency and durability of the ultrasonic motor. We already proposed a numerical technique using the finite element method (FEM) on the basis of incremental theory to analyze the behavior of the complex contact zone which contains non-contact zone, slip contact zone and stick contact zone in a non-rotating rotor as a static contact problem. In this paper, we expand this numerical technique from a non-rotating rotor to a rotating rotor and propose a numerical technique to analyze the dynamic behavior of this complex contact zone. Moreover, we clear the dynamic contact mechanism and the driving characteristics of the ultrasonic motor such as the dependency of driving torque on the maximum frictional co-efficient.
An Improved Method for Designing Flexure-Based Nonlinear Springs
Authors: Meng Qiaoling , Berselli Giovanni , Vertechy Rocco , Castelli Vincenzo Parenti
Published: September 2013

Monolithic Flexure-based Compliant Mechanisms (MFCM) can functionally act as nonlinear springs by providing a desired load-displacement profile at one point on their structure. Once the MFCM topology is chosen, these particular springs can be conveniently synthesized by resorting to the well-known Pseudo-Rigid-Body approximation, whose accuracy strongly depends on the modeling precision of the flexures’ principal compliance. For various types of flexures, closed-form solutions have been proposed which express the compliance factors as functions of the flexure dimensions. Nonetheless, the reliability of these analytical relations is limited to slender, beam-like, hinges undergoing small deflections. In order to overcome such limitations, this paper provides empirical equations, derived from finite element analysis, that can be used for the optimal design of circular, elliptical, and corner-filleted flexural hinges with general aspect ratios on the basis of both principal compliance and maximum bearable stress. As a case study, a nonlinear spring conceived as a four-bar linkage MFCM is synthesized and simulated by means of finite element analysis. Numerical results confirm that the aforementioned empirical equations outperform their analytical counterparts when modeling thick cross-section hinges undergoing large deflections.
Kinematical Model and Topology Patterns of a New 6-Parallel-Legged Walking Robot
Authors: Yang Pan , Gao Feng
Published: September 2013

In this paper, a new kind of 6-legged robot is presented. It was designed for drilling holes on the aircraft surface. Each leg of the robot is a 3-DOF parallel mechanism and the actuation can be controlled both by position and force. The mechanism design method of the robot is discussed. The relationship between control method and motion topology under different working conditions is studied. The kinematical model is built, based on which the motion plan are made. The control method is position-force control, so the calculation of actuation force is done. Finally, the simulation result is showed: the robot can drill on the fuselage surface successfully and the position-force control method can improve its performance a lot.
A Computational Framework for Supporting Innovation in Product Development Through Collaboration and Simulation
Authors: Galea Amanda , Farrugia Philip J. , Francalanza Emmanuel , Borg Jonathan C.
Published: September 2013

This paper deals with the development of a computational framework that aims to facilitate innovative endeavours during product development. A problem analysis carried out revealed that both stakeholder collaboration and artefact simulation are considered important for supporting innovation, the first through the availability of more ideas and the latter for analysing the feasibility of these ideas prior to their implementation in practice. However, it was observed that the use of collaboration tools and simulation tools is still lacking in practice mainly due to lack of awareness or perceived lack of necessity. This research thus aims to develop a framework that helps support innovation in product development through the use of these tools. From the preliminary evaluation of the solution developed, it was found that the portal and its underlying framework are indeed useful for supporting innovation.
Virtual Reality Providing Ground Truth for Machine Learning and Programming by Demonstration
Authors: Roßmann Jürgen , Schlette Christian , Wantia Nils
Published: September 2013

In this contribution, it is demonstrated how the development, parameterization and evaluation of an intelligent cognitive system can be supported by means of Virtual Reality (VR). Based on new approaches in object and action recognition, the consortium in the EU funded project IntellAct is developing such an automated system for the intelligent understanding of manual tasks and robot-based manipulations.

In this context, the VR setup of the Institute for Man-Machine Interaction (MMI) is able to deliver ideal data, such as detailed positions and joint data of objects and kinematics involved. In addition, it allows for the synthesis of distinct and error-free data, such as collisions, bounding boxes and contact events. This way, Virtual Reality serves as a reference and source for “ground truth” data for designing, training and benchmarking the intelligent cognitive system during its development and parameterization. Furthermore this approach enables descriptive and secure ways for the visualization of results in the targeted environments, such as the highly automated laboratories on-board the International Space Station (see Fig. 1).
A 2-DOF Large Stroke Flexure Based Positioning Mechanism
Authors: Folkersma K. G. P. , Boer S. E. , Brouwer D. M. , Herder J. L. , Soemers H. M. J. R.
Published: September 2013

Flexure based stages are particularly important for vacuum applications because they combine low hysteresis, no wear and no contamination with a high supporting stiffness. However, flexure hinges inherently lose stiffness in supporting directions when deflected. Therefore the workspace to footprint ratio is limited. In this article we present the design and modeling of a two degrees of freedom cross flexure based stage that combines a large workspace to footprint ratio with high vibration mode frequencies. Because the mechanism is an assembly of optimized components, the stage is designed according to the exact constraint principle to avoid build-up of internal stresses due to misalignment. FEM results have been validated by measurements on an experimental test setup. The test setup has a workspace-area to footprint ratio of 1/32. The lowest measured natural frequency with locked actuators over a 60 × 60mm workspace was 80Hz.
Accounting for Nonlinearities in Protocols for Open-Loop Fault Compensation
Authors: DiBerardino Louis A. , Dankowicz Harry
Published: September 2013

In this paper, we consider model examples of dynamical systems with only a few degrees of freedom and with desirable symmetry properties and explore compensating control strategies for retaining robust symmetric system response even under symmetry-breaking defects. The analysis demonstrates the distinct differences between linear versions of these models, in which open-loop fault-compensating strategies are always found, and weakly nonlinear counterparts with varying degrees of asymmetry, for which a multitude of locally optimal solutions may co-exist. We further formulate a candidate open-loop optimization protocol for fault compensation applied to self-healing systems, which respond to symmetry-breaking defects by a continuous process of fault correction. The analysis shows that such a protocol exhibits discontinuous changes in the control strategy as the self-healing system successively regains its original symmetry properties. In addition, it is argued that upon return to a symmetric configuration, such a protocol may result in a different control strategy from that applied prior to the occurrence of a fault.
Fitting Weighted Total Least-Squares Planes and Parallel Planes to Support Tolerancing Standards
Authors: Shakarji Craig M. , Srinivasan Vijay
Published: September 2013

We present elegant algorithms for fitting a plane, two parallel planes (corresponding to a slot or a slab) or many parallel planes in a total (orthogonal) least-squares sense to coordinate data that is weighted. Each of these problems is reduced to a simple 3×3 matrix eigenvalue/eigenvector problem or an equivalent singular value decomposition problem, which can be solved using reliable and readily available commercial software. These methods were numerically verified by comparing them with brute-force minimization searches. We demonstrate the need for such weighted total least-squares fitting in coordinate metrology to support new and emerging tolerancing standards, for instance, ISO 14405-1:2010. The widespread practice of unweighted fitting works well enough when point sampling is controlled and can be made uniform (e.g., using a discrete point contact Coordinate Measuring Machine). However, we demonstrate that nonuniformly sampled points (arising from many new measurement technologies) coupled with unweighted least-squares fitting can lead to erroneous results. When needed, the algorithms presented also solve the unweighted cases simply by assigning the value one to each weight. We additionally prove convergence from the discrete to continuous cases of least-squares fitting as the point sampling becomes dense.
An Approach to Study Impact of Public Policy, Exogenous Variables, and Vehicle Design on Greenhouse Gas Emission
Authors: Razu Swithin S. , Takai Shun
Published: September 2013

The aim of this paper is to study the impact of public policies and uncontrollable (exogenous) variables as well as optimal vehicle design on greenhouse gas (GHG) emissions in the US transportation sector. The overall model is divided into the government model and an enterprise model. To examine the effect of GHG emissions and exogenous variables, the optimization model includes public policy, exogenous variables, and a market mix focusing on the GHG effects of four different types of vehicles, 1) gasoline-based 2) gasoline-electric hybrid or alternative-fuel vehicles (AFVs), 3) battery-electric (BEVs) and 4) fuel-cell vehicles (FCVs). The public policies taken into consideration are infrastructure investments for hydrogen fueling stations and subsidies for purchasing AFVs. An exogenous variable taken into consideration are gasoline prices. For each selection of public policy and exogenous variables in the government model, the enterprise model finds the optimum vehicle design that maximizes profit and updates the market mix, from which the government model can estimate GHG emissions for that selection and can choose a public policy accordingly to produce a desired effect. This paper demonstrates the model using FCV design as an illustrative example.
Nonlinear Vibrations of Functionally Graded Cylindrical Shells: Effect of the Geometry
Authors: Strozzi Matteo , Pellicano Francesco , Zippo Antonio
Published: September 2013

In this paper, the effect of the geometry on the nonlinear vibrations of functionally graded (FGM) cylindrical shells is analyzed. The Sanders-Koiter theory is applied to model the nonlinear dynamics of the system in the case of finite amplitude of vibration. The shell deformation is described in terms of longitudinal, circumferential and radial displacement fields. Simply supported boundary conditions are considered. The displacement fields are expanded by means of a double mixed series based on harmonic functions for the circumferential variable and Chebyshev polynomials for the longitudinal variable. In the linear analysis, after spatial discretization, mass and stiff matrices are computed, natural frequencies and mode shapes of the shell are obtained. In the nonlinear analysis, the three displacement fields are re-expanded by using approximate eigenfunctions obtained by the linear analysis; specific modes are selected. The Lagrange equations reduce nonlinear partial differential equations to a set of ordinary differential equations. Numerical analyses are carried out in order to characterize the nonlinear response of the shell. A convergence analysis is carried out to determine the correct number of the modes to be used. The analysis is focused on determining the nonlinear character of the response as the geometry of the shell varies.
Computationally Efficient Imprecise Uncertainty Propagation in Engineering Design and Decision Making
Authors: Ghosh Dipanjan D. , Olewnik Andrew
Published: September 2013

Modeling uncertainty through probabilistic representation in engineering design is common and important to decision making that considers risk. However, representations of uncertainty often ignore elements of “imprecision” that may limit the robustness of decisions. Further, current approaches that incorporate imprecision suffer from computational expense and relatively high solution error. This work presents the Computationally Efficient Imprecise Uncertainty Propagation (CEIUP) method which draws on existing approaches for propagation of imprecision and integrates sparse grid numerical integration to provide computational efficiency and low solution error for uncertainty propagation. The first part of the paper details the methodology and demonstrates improvements in both computational efficiency and solution accuracy as compared to the Optimized Parameter Sampling (OPS) approach for a set of numerical case studies. The second half of the paper is focused on estimation of non-dominated design parameter spaces using decision policies of Interval Dominance and Maximality Criterion in the context of set-based sequential design-decision making. A gear box design problem is presented and compared with OPS, demonstrating that CEIUP provides improved estimates of the non-dominated parameter range for satisfactory performance with faster solution times. Parameter estimates obtained for different risk attitudes are presented and analyzed from the perspective of Choice Theory leading to questions for future research. The paper concludes with an overview of design problem scenarios in which CEIUP is the preferred method and offers opportunities for extending the method.
Modeling Product Form Preference Using Gestalt Principles, Semantic Space, and Kansei
Authors: Lugo José E. , Batill Stephen M. , Carlson Laura
Published: September 2013

Engineers describe design concepts using design variables. Users develop their visual judgment of products by mentally grouping design variables according to Gestalt principles, extracting meaning using semantic dimensions and attaching attributes to the products, as reflected in Kansei methodology. The goal of this study was to assess how these different sources of information and representations of product form (design variables, Gestalt variables, Kansei attributes, and semantic dimensions) could combine to best predict product preference for both designers and users. Sixteen wheel rim designs were created using four design variables that were also combined into higher-order Gestalt variables. Sixty-four participants viewed each rim, and rated it according to semantic dimensions and Kansei attributes, and provided an overall “like” rating. The most reliable prediction of product preference were developed using Gestalt variables in combination with the meaning and emotion the users attached to the product. Finally, implications for designers are discussed.
A System for Generating Electricity Using the Passage of Train Wheels for Improving Railroad Track Safety
Authors: Pourghodrat Abolfazl , Nelson Carl A.
Published: September 2013

The dangerous nature and history of railroad grade crossings (especially unprotected crossings in remote areas lacking costly electrical infrastructure) motivates engineering efforts to reduce the number of fatalities and injuries. Several approaches and devices have been investigated and developed to harvest energy, mostly from vertical deflection of railroad track to power automated warning systems and track health monitoring sensors. While most of this previous work relied on harvesting energy from the vertical deflection of the railroad track, this paper proposes a mechanism for generating electricity from the passage of each train wheel. A cam-follower mechanism was designed initially to meet the requirements of low noise, shock and wear, and was subsequently used and improved to design a system capable of generating electricity efficiently from the motion of trains traveling in either direction. The development of the device as well as analysis of its predicted power production capability is presented in this paper.
Modeling, Fabrication, and Testing of a Nanoinjection Lance Array for Simultaneous Multi-Cell Injections
Authors: Toone Nathan C. , Teichert Gregory H. , Brewer Steven J. , Jensen Brian D.
Published: September 2013

A nanoinjection lance array has been developed to inject foreign genetic material into thousands of cells at once using electrophoresis to attract and repel particles to and from the lances. A unique combination of isotropic and anisotropic etch processes are used to fabricate the four million 1 μm by 8 μm solid lances on a 2 cm by 2 cm chip. Initial studies show high cell viability when the lance array is used to pierce through a culture of HeLa cancer cells, often used for genetic research. A mathematical computer model simulating motion of attracted or repelled particles informs the design of the nanoinjection lance array system. The nanoinjection lance array provides an efficient, convenient, and quick way to simultaneously inject thousands of cells for a wide range of genetic research applications.
A Metamorphic Erectable Cell Restraint (MECR)
Authors: Teichert Gregory H. , Aten Quentin T. , Easter Melanie , Burnett Sandra , Howell Larry L. , Jensen Brian D.
Published: September 2013

This paper introduces a metamorphic erectable cell restraint (MECR) to provide cell restraint in genetic research. A micro-electromechanical systems (MEMS) metamorphic mechanism with two phases of motion was designed to grasp individual embryos about their midplane. The first phase of motion lifts a compliant gripper approximately 40 μm (about half the diameter of an embryo). The gripper then closes in the second phase to grasp the embryo. The metamorphic mechanism includes compliant mechanism components which are analyzed here. A microscale prototype was fabricated from polysilicon and used to demonstrate the mechanism’s two phase motion.
Multi-Objective Optimization of Stiffness and Workspace for a Parallel Kinematic Machine
Authors: Chi Zhongzhe , Zhang Dan
Published: September 2013

This paper presents optimizations of a parallel kinematic manipulator used for a machine tool in terms of its workspace and stiffness. The system stiffness and workspace of the parallel manipulator are conducted in the paper. In order to locate the maximum system stiffness and workspace, single and multi objective optimizations are performed in terms of rotation angles in x and y axes and translation displacement in z axis with Genetic Algorithms. By optimizing the design variables including geometric dimensions of the manipulator, the system stiffness and workspace of the proposed parallel kinematic manipulator has been greatly improved.