bluuebunny/crossref_metadata_2025 huggingface dataset:
Principles of Dynamics for Design Applied to a Brush-Belt Material-Transfer System
Authors: Nguyen Kim D. , Dankowicz Harry
Published: January 2015

This paper considers the performance characteristics of a brush-based material-transfer system, and the frictional interactions that result from the presence of particulate contaminants. The analysis of the dynamics of spherical objects transported through a cartridge by the brush is applied to isotropic and anisotropic belt designs. Experimental measurements of the load on individual objects, obtained using an instrumented cantilever, are compared with the predictions from a heuristic model, as well as preliminary observations from a qualitative bifurcation analysis of a piecewise-smooth dynamical system, in which a spring-loaded object slides along a looped belt with patches of distinct frictional properties.
A Multi-Scale Materials Modeling Method With Seamless Zooming Capability Based on Surfacelets
Authors: Huang Wei , Wang Yan , Rosen David W.
Published: January 2015

In multi-scale materials modeling, it is desirable that different levels of details can be specified in different regions of interest without the separation of scales so that the geometric and physical properties of materials can be designed and characterized. Existing materials modeling approaches focus on the representation of the distributions of material compositions captured from images. In this paper, a multi-scale materials modeling method is proposed to support interactive specification and visualization of material microstructures at multiple levels of details, where designer’s intent at multiple scales is captured. This method provides a feature-based modeling approach based on a recently developed surfacelet basis. It has the capability to support seamless zoom-in and zoom-out. The modeling, operation, and elucidation of materials are realized in both the surfacelet space and the image space.
An Approach for Measuring Information Content of Textual Engineering Requirements Using a Form-Neutral Representation
Authors: Sen Chiradeep , Mukhopadhyay Alolika , Fields John , Ameri Farhad
Published: January 2015

This paper demonstrates a generic approach for measuring the information content of artifacts produced and used in early stages of mechanical design. Engineering design requirements are selected for information content analysis for illustration. In this method, requirements in natural language are translated to an Entity-Relation-Attribute-Value (ERAV) model composed of well-defined elements. A protocol for this translation is proposed and validated. Four different metrics, based on raw element count, count weighted by arbitrary ordinal scale, count weighted by node cardinality, and Shannon’s entropy are then applied to the ERAV model for measuring information content. The method proposed is generic enough to be applied to most design documents that use natural language as the knowledge representation formalism.
Effects of Expectation Uncertainty and Surprise on Quality Perception Factors of Expectation Effect
Authors: Yanagisawa Hideyoshi , Mikami Natsu
Published: January 2015

In the user’s perception of a product’s qualities, the state of their sensory modality may shift from one state to another. For example, users see and then touch a product to perceive its texture. Between such state transitions, users have expectations regarding their subsequent states based on their experience of a current state event. Expectation effect is a psychological effect in which prior expectation changes posterior perception itself. The effect is a key factor to design user’s emotions induced by expectation disconfirmation as well as designing a perceived quality based on prior expectations. Although experimental findings on the expectation effect exist in a variety of research disciplines, general and theoretical models of the effect have been largely neglected. The present authors previously found out the visual expectation effect on tactile perceptions of surface texture. The causes of the expectation effect, however, remain largely unexplored. To intentionally design the expectation effect, general and theoretical models that estimates conditions of the effect is needed. In this paper, we propose a theoretical model of the expectation effect using information theory and an affective expectation model (AEM). We hypothesize that Shannon’s entropy of the prior subjective probability distributions of posterior experience determines the occurrence of the expectation effect and that the amount of information gained after experiencing a posterior event is positively correlated with the intensity of the expectation effect. We further hypothesize that a conscious level of expectation discrepancy distinguishes between two types of expectation effect, namely, assimilation and contrast. To verify these hypotheses, we conducted an experiment in which participants responded to the tactile qualities of surface texture. In the experiment, we extracted the visual expectation effect on tactile roughness during a sensory modality transition from vision to touch and analyzed the causes of the effect based on our hypotheses. The experimental results indicated the appropriateness of the proposed model of the expectation effect.
Addition of Springs and its Impact on Cable-Driven Serial Manipulators
Authors: Duan Qingjuan , Jin Xin , Agrawal Sunil K.
Published: January 2015

Serial multi-body systems can be driven by cables routed through the links to achieve the desired range of motion. Placement and routing of the cables alter the performance characteristics of the manipulator. There are possible applications for such mechanisms where low moving inertia is required. One of the challenges in the design of cable-driven mechanisms is to keep cables in tension during the motion. In this article, the addition of springs and its impact on workspace is investigated. A 2-link cable-driven robot is used to illustrate changes in Wrench Feasible Workspace (WFW) as springs are added between the serial manipulator and the ground or between the links.
Component Size Optimization of a Wind-Integrated Microgrid System With Dispatch Strategy and Resource Uncertainty
Authors: Hung Tzu-Chieh , Chan Kuei-Yuan
Published: January 2015

The global quest for energy sustainability has motivated the development of technology for efficiently transforming various natural resources into energy. Combining these alternative energy sources with existing power systems requires systematic assessments and planning. The present study investigates the conversion of an existing power system into one with a wind-integrated microgrid. The standard approach applies wind resource assessment to determine suitable wind farm locations with high potential energy and then develops specific dispatch strategies to meet the power demand for the wind-integrated system with low cost, high reliability, and low impact on the environment. However, the uncertainty in wind resource results in fluctuating power generation. The installation of additional energy storage devices is thus needed in the dispatch strategy to ensure a stable power supply. The present work proposes a design procedure for obtaining the optimal sizing of wind turbines and storage devices considering wind resource assessment and dispatch strategy under uncertainty. Two wind models are developed from real-world wind data and apply in the proposed optimization framework. Based on comparisons of system reliability between the optimal results and real operating states, an appropriate wind model can be chosen to represent the wind characteristics of a particular region. Results show that the trend model of wind data is insufficient for wind-integrated microgrid planning because it does not consider the large variation of wind data. The wind model should include the uncertainties of wind resource in the design of a wind-integrated microgrid system to ensure high reliability of optimal results.
A Formal Text Description of Mechanisms for Their Automated Synthesis
Authors: Dmitrochenko Oleg , Matikainen Marko , Mikkola Aki
Published: January 2015

A single-line symbolic notation is proposed for description of an arbitrary mechanism or a multibody system. The kinematics is represented by a sequence of elementary transformations; each of those being marked by a reserved alphabetic character. Force and constraint links between the bodies are also defined by reserved characters. The parameters of the system, such as identifiers of degrees of freedom, inertia parameters and others, are assigned default names if not specified. However, user-defined names, parameters and functions can be placed instead, if needed. The proposed description in its shortest form is suitable for academic purpose to identify only the essential properties of a multibody system. In an extended form, by explicit mentioning names of variables and parameters and other data like initial conditions, this description can serve as input data for multibody analysis software. Examples from academic area and technical applications are given to show the applicability of the proposed description.
On the Thermomechanical Response of HTPB Composite Beams Under Near-Resonant Base Excitation
Authors: Woods Daniel C. , Miller Jacob K. , Rhoads Jeffrey F.
Published: January 2015

Currently, there is a pressing need to detect and identify explosive materials in both military and civilian settings. While these energetic materials vary widely in both form and composition, many traditional explosives consist of a polymeric binder material with embedded energetic crystals. Interestingly, many polymers exhibit considerable self-heating when subjected to harmonic loading, and the vapor pressures of many explosives exhibit a strong dependence on temperature. In light of these facts, thermomechanics represent an intriguing pathway for the stand-off detection of explosives, as the thermal signatures attributable to motion-induced heating may allow target energetic materials to be distinguished from their more innocuous counterparts. In the present work, the mechanical response of a polymeric particulate composite beam subjected to near-resonant base excitation is modeled using Euler-Bernoulli beam theory. Significant sources of heat generation are identified and used with distributed thermal models to characterize the system’s thermomechanical response. In addition, the results of experiments conducted using a hydroxyl-terminated polybutadiene (HTPB) beam with embedded ammonium chloride (NH4Cl) crystals are presented. The thermal and mechanical responses of the sample are recorded using infrared thermography and scanning laser Doppler vibrometry, and subsequently compared to the work’s analytical findings. By adopting the combined research approach utilized herein, the authors seek to build upon recent work and bridge the considerable gap that exists between theory and experiments in this specific field. To this end, the authors hope that this work will represent an integral step in enhancing the ability to successfully detect explosive materials.
A Cable Based Active Variable Stiffness Module With Decoupled Tension
Authors: Zhou Xiaobo , Jun Seung-kook , Krovi Venkat
Published: January 2015

Variable-stiffness modules add significant robustness to mechanical systems during forceful interactions with uncertain environments. Traditionally, most existing variable stiffness modules tend to be bulky by virtue of their use of solid components making them less suitable for mobile applications. In recent times, pretensioned cable-based modules have been proposed to reduce weight. While passive, these modules depend on significant internal tension to provide the desired stiffness and stiffness modulation capability tends to be limited. In this paper, we present design, analysis and testing of a cable based active variable stiffness module that can be realized to achieve a large stiffness range. Controlled changes in structural parameters (independent of cable length actuation) now permits independent modulation of the perceived stiffness with desired tension. This capability is now systematically evaluated on a hardware-in-the-loop experimental setup and results are analyzed.
Towards Statically Balanced Compliant Joints Using Multimaterial 3D Printing
Authors: Bruyas Arnaud , Geiskopf François , Renaud Pierre
Published: January 2015

Compliant joints are widely used in mechanisms when accurate movements are required. With no assembly requested, they are also a great tool for mesoscale robotics, a field in which compactness and large joint amplitudes are necessary features. In this paper, an original multi-material compliant revolute joint is presented. Taking advantage of multi-material 3D printing, it exhibits a novel design with the integration of an hyper-elastic material. Thanks to a helical shape design, a large range of motion is obtained, and the incompressibility of the hyper-elastic material is used to improve the stiffness properties of the joint while keeping it compact. The spring effect of compliant joints makes mechanism actuation more difficult. The proposed joint is therefore designed with an integrated static balancing system in order to minimize actuation torques. The balancing system is composed of a bistable mechanism, which geometry optimization is presented. Experimental assessment demonstrate that the joint possesses a range of motion of 120°, and the balancing system reduces actuation moments by almost 60%.
Experimental Study of an Airplane Accident Evacuation/Rescue Simulation Using 3D Kinematic Digital Human Models
Authors: Kakizaki Takao , Urii Jiro , Endo Mitsuru
Published: January 2015

The 3D mass evacuation simulation of an airplane accident is experimentally verified. Evacuee motion has been experimentally investigated by building a test field that emulates the interior of an actual regional airliner with a capacity of approximately 100 passengers. The experiment results indicate that the evacuation time tends to be affected by the number of passengers and the evacuee guidance at the emergency exit. The results also indicate that any evacuation delay in exiting by individual passengers only slightly affects the total evacuation time because of evacuee congestion in the aisles. Moreover, the importance of evacuation guidance notification was investigated based on the evacuation-order variance. Finally, the experimental results were compared to the corresponding simulation results. Simulations using appropriate evacuee walking speeds can provide valid evacuation times, which are the most important factor in designing evacuation drills. Consequently, these results should be applied to existing 3D simulations using precise KDH models for more accurate mass evacuation/rescue simulations.
Simulation and Experimental Investigation of an Energy Harvester Utilizing Flow-Induced Vibration
Authors: Abd El-Mageed Mostafa G. , Arafa Mustafa , Elaraby Mohamed
Published: January 2015

This work exploits harvesting energy from fluid flow by means of a device that is inserted in the flow stream. The device is designed to exhibit desirable hydrodynamic characteristics that advocate flow-induced oscillations, which can be converted into useful power. In this context, a cantilever beam carrying an open semicircular cylinder at its tip is placed in a flowing water stream. The hydrodynamic loads cause the beam to undergo galloping motions in the transverse direction. The beam, which is made up of laminated polymer/polyvinylidene difluoride (PVDF) layers, extracts electrical energy from the sustained cyclic mechanical motion. A numerical model is developed to predict the system dynamics in terms of its design parameters. The results are supported by experimental measurements of the output voltage over a range of water speeds and load resistance.
Six Dimensional Compliance Analysis of Ortho-Planar Springs for a Continuum Manipulator
Authors: Qiu C. , Qi P. , Liu H. B. , Althoefer Kaspar , Dai Jian S.
Published: January 2015

Ortho-planar spring is a compact spring that generates the motion based on the deformation of flexure elements, and it has wide applications in the compliant robotic designs. Previous studies only investigate the out-of-plane compliance of ortho-planar spring and fewer work pays attention to its angular compliance. To address this issue, this paper provides an analytical method to study both the linear and angular compliance characteristics of ortho-planar spring for the first time. In the frame work of screw theory, the symbolic formula of platform’s compliance matrix was obtained based on the hybrid integration of beam elements. Subsequently non-dimensional geometric parameters were introduced to compare the compliance characteristics of planar spring, which revealed the ortho-planar spring also demonstrates large bending compliance. Numerical studies of angular compliance of planar spring were provided, and they showed good agreements with the finite element simulations in a large working range. Based on the numerical study, a physical prototype of one continuum structure assembled with planar springs was provided and it demonstrated a large flexibility compared to other previous designs, which suggests the ortho-planar spring has potential value in developing continuum manipulators in related medical surgery and biorobotic research fields.
Components of a Framework for the Design of Energy Services for Villages in Developing Countries
Authors: MacCarty Nordica , Bryden Kenneth (Mark)
Published: January 2015

The development of energy services for the 40% of the world’s population currently living in energy poverty is a challenging design problem. There are competing and often conflicting objectives between stakeholders from global to user viewpoints, and the confounding effects of real-world performance, rebound, and stacking of technologies makes the determination of optimal strategies for off-grid village energy complicated. Yet there are holistic and lasting solutions that can adequately address the technical, social, economic, and environmental constraints and satisfy the goals of all stakeholders. These solutions can be better identified by systematically considering five major qualitative and quantitative outcomes including 1) energy access and efficiency, 2) climate benefits, 3) health impacts, 4) upfront and recurring economic and opportunity costs, and 5) quality of life for the user in terms of several metrics. Beginning with a comprehensive survey of energy uses in a village and current and potential technological options to meet those needs, this article proposes a methodology to identify and quantify these five outcomes for various intervention scenarios. These evaluations can provide a better understanding of the constraints, trade-offs, sensitivity to various factors, and conditions under which certain designs are appropriate for the village energy system. Ultimately a balance of all five objectives is most likely to result in equitable, user-driven, and sustainable solutions.
A Novel Micro Aerial Vehicle Design: The Evolution of the Omnicopter MAV
Authors: Long Yangbo , Gelardos Andreas , Cappelleri David J.
Published: January 2015

This paper presents an evolution on the configuration of a novel micro aerial vehicle (MAV) design, the Omnicopter MAV. The first generation Omnicopter prototype has an actuation system with eight degrees of freedom (DOFs) consisting of 5 brushless direct current (BLDC) motors and 3 servo motors. It is composed of a carbon fiber rod built airframe, 2 central counter-rotating coaxial propellers for thrust and yaw control, and 3 perimeter-mounted electric ducted fans (EDFs) with servo motors performing thrust vectoring. During the development of the second generation prototype, we simplified and 3D printed the frame to increase stiffness, robustness and manufacturability, and reduced the actuation DOFs from 8 to 7 by removing the top propeller and using just the bottom one for yaw control to improve performance. Flight controller and control allocator designs and test flight results for this new configuration are presented in this paper.
Reliability-Based Multidisciplinary Design Optimization Using Subset Simulation Analysis and its Application in the Hydraulic Transmission Mechanism Design
Authors: Meng Debiao , Huang Hong-Zhong , Wang Zhonglai , Zhang Xiaoling , Liu Yu
Published: January 2015

The traditional Monte Carlo Simulation (MCS) approach can provide high reliability analysis accuracy, however, with low computational efficiency. Especially, it is computationally expensive to evaluate a very small failure probability. In this paper, a Subset Simulation-based Reliability Analysis (SSRA) approach is combined with the Multidisciplinary Design Optimization (MDO) to improve the computational efficiency in the Reliability based Multidisciplinary Design Optimization (RBMDO) problems. Furthermore, the Sequential Optimization and Reliability Assessment (SORA) approach is utilized to decouple the RBMDO into MDO and reliability analysis. The formula of MDO with SSRA within the framework of SORA (MDO-SSRA-SORA) is proposed to solve the design optimization problem of hydraulic transmission mechanism.
A Study of Automotive Greenhouse Gas Emissions and Reduction Opportunities Through Adoption of Electric Drive Vehicles
Authors: Laberteaux Kenneth P. , Clewlow Regina R. , Hamza Karim
Published: January 2015

This paper explores opportunities for reductions in lifecycle greenhouse gas (GHG) emissions through adoption of electric drive vehicles (EDV), including hybrid, plug-in hybrid and battery electric vehicles. EDVs have generally lower GHG emission rates during operation than similar-class conventional vehicles (CV). However, a key observation is that GHG reductions per mile are much larger during city driving conditions than on the highway. An examination of the estimated GHG emissions is conducted for city and highway driving conditions for several CV and EDV models based on testing results from the US Environmental Protection Agency (EPA), then compared with key findings from the 2009 National Household Travel Survey (NHTS 2009). Through an empirical analysis of actual driving patterns in the U.S., this study highlights potential missed opportunities to reduce transportation GHG emissions through the allocation of incentives and/or regulations. Key findings include the significant potential to reduce GHG emissions of taxis and delivery vehicles, as well as driving pattern-based incentives for individual vehicle owners.
Toward Patient-Specific Computational Study of Aortic Diseases: A Population Based Shape Modeling Approach
Authors: Li Kang , Qian Xiaoping , Martin Caitlin , Sun Wei
Published: January 2015

Patient-specific computational study of aortic disease provides a powerful means for diagnosis and pre-operative planning. However, creating patient-specific computational models can be time-consuming due to the fact that anatomical geometries extracted from clinical imaging data are often incomplete and noisy. This paper presents an approach for constructing statistical shape models (SSMs) for aortic surfaces with the eventual goal of mapping the mean aorta geometries to raw surface data obtained from the clinical images for each new patient so that patient-specific models can be automatically constructed.

The input aortic models in this study come in the form of triangle meshes generated from CT scans on 6 patients. Statistical models with modes that characterize the variation pattern are found after optimizing the group-wise correspondence across the aorta training set. We use the direct reparametrization approach to efficiently manipulate shape correspondence. We use B-spline based differentiable shape representation for the training set and use the adjoint method for deriving analytical gradients in a gradient based approach for manipulating the shape correspondence to minimize the description length of the resulting SSM. Our numerical result shows that the evaluation measures of the optimized statistical model have been significantly enhanced.
Development of an Information Model for the Integration of Product Design and Sustainability Evaluation
Authors: Zhang Heng , Roy Utpal
Published: January 2015

Sustainability evaluation is an important activity for product designers to make “green” decisions when applying the rules for “Design for Sustainability”. It allows the designers to have a quantifiable conception of sustainability about his/her design in the real time. The successful evaluation mechanisms necessitate a closed and complete information integration between the product design methodology and sustainability evaluation techniques. In this paper, we propose an integration framework, which brings the environmental impact assessment into the early product design stages for design sustainability analysis. An information model, which is based on the current CAD systems, has been developed to link the essential components in the framework for building a successful green product design system. A case study that simulates a part design scenario has been given to demonstrate the use of the proposed information model.
Nanocomposites Based on Multiwalled Carbon Nanotubes With Effective Young’s Modulus Dependent on Number of Layers
Authors: Joshi Preeti , Upadhyay S. H.
Published: January 2015

The excellent combination of high strength, stiffness, low density and aspect ratio makes carbon nanotubes ideal reinforcement for nanocomposites. The load transfer between the outer and inner layers of multiwalled carbon nanotubes (MWCNT) is one of the important factor in the reinforcement of nanocomposites. In this work, the effect of variation in number of layers of multiwalled carbon nanotubes on effective tensile, compressive and transverse modulus of composite is evaluated. A 3-D finite element model based on representative volume element, consisting of multiwalled carbon nanotube made of shell elements surrounded by solid matrix material is built. With the increase in number of layers in multiwalled carbon nanotubes, the compressive modulus of composite increases, while the tensile modulus decreases. The transverse modulus of composite is found to increase, with the increase in number of layers in MWCNT. The finite element results for composite are compared with the rule of mixtures results using formulae.
Block Adjacency Matrix Method for Analyzing the Configuration Transformations of Metamorphic Parallel Mechanisms
Authors: Li Duanling , Li Chunxia , Zhang Zhonghai , Kong Xianwen
Published: January 2015

Metamorphic transformation is a fundamental and key issue in the design and analysis of metamorphic mechanisms. It is tedious to represent and calculate the metamorphic transformations of metamorphic parallel mechanisms using the existing adjacency matrix method. To simplify the configuration transformation analysis, we propose a new method based on block adjacency matrix to analyze the configuration transformations of metamorphic parallel mechanisms. A block adjacency matrix is composed of three types of elements, including limb matrices that are adjacency matrices each representing a limb of a metamorphic parallel mechanism, row matrices each representing how a limb is connected to the moving platform, and column matrices each representing how a limb is connected to the base. Manipulations of the block adjacency matrix for analyzing the metamorphic transformations are presented systematically. If only the internal configuration of a limb changes, the configuration transformations can be obtained by simply calculating the corresponding limb matrix. A 3-URRRR metamorphic parallel mechanism, which has five configurations including a 1-DOF translation configuration and a 3-DOF spherical motion configuration, is taken as an example to illustrate the effectiveness of the proposed approach to the metamorphic transformation analysis of metamorphic parallel mechanism.
Molecular Dynamics Study of Nano-Tribological Properties of Silicon Nitride Films
Authors: Li Longqiu , Wang Shufeng , Ovcharenko Andrey , Wang Wuyi
Published: January 2015

Silicon nitride films were attracting extensive research interest in the past few decades as hard disk protective coating, especially the beta-silicon nitride (β-Si3N4) films and amorphous silicon nitride (SiNx) films, which have high hardness, chemical durability and low friction coefficient properties against wear, corrosion and reducing the friction resistance, respectively. Considerable efforts have been made in studying silicon nitride. However, it’s difficult to determine its nano-tribological properties experimentally since the results were affected by a lot of contact and environment conditions.

The molecular dynamics (MD) simulation method is employed in this work. A rigid diamond sphere modeled as a spherical tip are sliding over a layered silicon nitride film substrate, respectively, to investigate the tribological properties of silicon nitride films. The effect of the relative sliding velocity and sliding direction, the normal force and the thickness of crystalline silicon nitride films on the friction coefficient of silicon nitride films were investigated.
Influence of the Number of AGVs on Products Conveyance Efficiency in AGV Transportation System Based on Knowledge of Taxis
Authors: Suzuki Tsuguhito , Hirogaki Toshiki , Aoyama Eiichi , Ogawa Keiji , Ito Taichi
Published: January 2015

Manufacturing systems, such as the flexible manufacturing system (FMS), have recently changed to accommodate the production of various types and volumes of products. In the FMS, however, it is difficult to change the layout of the factory and solve problems that arise. Therefore, the importance of automated guided vehicles (AGVs) is increasing because they can flexibly respond to changes in facilities and factory layouts. However, there have not been any studies that take into account the many indefinite and accidental elements regarding AGV systems. Applications of knowledge in one domain to a different domain have been drawing much attention. Such activity is called a mimetic solution. We investigated applying the knowledge of traffic engineering regarding passenger transport to conveyance of AGVs. We propose an autonomous conveyance system for AGVs based on taxi transportation strategies to solve indefinite and accidental problems. The system focuses on applying traffic engineering knowledge regarding a flexible taxi system. A taxi is a transport unit in a traffic system involving high flexibility in traveling routes and arrival/departure points.

We also applied the waiting mode of taxis at stations where AGVs pick up and drop off products (P/Ds) as AGV rules to our system and investigated the system’s effectiveness and adaptability to schedule changes in the factories. To adopt a waiting mode as AGV rules, we determine the arrival/departure points that AGVs wait and changing the number of AGVs and product intervals. In addition, collision between AGVs must be considered. If a collision occurs, we have to change the factory schedule. Therefore, we took into consideration AGV collisions. We estimated the matching time, conveyance efficiency, and number of approaches as assessment functions. The matching time is the period between when a load is generated and received, conveyance efficiency is the ratio of total distance to distance traveled while empty, and approaching AGVs denotes the risk of collision. Specifically, we discuss the effect of the number of AGVs on these parameters by considering the ratio of the number of AGVs to the number of P/Ds. We demonstrated that our system is effective in terms of high conveyance efficiency and reducing the number of approaches without decreasing matching time and with a suitable number of AGVs.
Multi-Mode Excitation of a Clamped-Clamped Microbeam Resonator
Authors: Younis Mohammad I.
Published: January 2015

We present modeling and simulation of the nonlinear dynamics of a MEMS resonator to two-source excitation. The resonator is composed of a clamped-clamped beam excited by a DC voltage load superimposed to two AC voltage loads of different frequencies. One frequency is chosen to be close to the first natural frequency of the beam and the other close to the third (second symmetric) natural frequency. A multi-mode Galerkin procedure is applied to extract a reduced-order model, which forms the basis of the numerical simulations. Time history response, Poincare’ sections, Fast Fourier Transforms FFT, and bifurcation diagrams are used to reveal the dynamics of the system. The results indicate complex nonlinear phenomena, which include quasi-periodic motion, torus bifurcations, and modulated chaotic attractors.
Preliminary Sketching and Prototyping: Comparisons in Exploratory Design-and-Build Activities
Authors: Faas Daniela , Bao Qifang , Yang Maria C.
Published: January 2015

This study explores the role of sketching when designers are creating fast, preliminary prototypes during hands on design-and-build activities. Many studies have noted the value of both sketching and the building of preliminary prototypes in the early stages of the design process. In a typical design scenario, exploratory sketches are made before prototypes are fabricated. However, in certain cases, the differences in the design exploration value of a sketch and a simple, preliminary prototype may not always be clear. In this study, three conditions for a design-and-built activity were compared: a control group (allowed to freely sketch throughout), a limited sketch group (only allowed to sketch at the beginning) and a no sketch group. The study was conducted twice, using two different prototyping materials each time. One that is assembly only (an Erector set) and one that requires both part fabrication and assembly (foam core). The performance of the prototypes, the type and quality of the sketches, and the relationship between sketches and prototypes were evaluated. Results for this study suggest that fast, preliminary prototypes are equally as useful for design exploration as sketching in building simple mechanisms, though results would likely be different for more complex design tasks.
Design Method to Achieve High Frequency Stability of Electrostatically Actuated Doubly-Clamped Nano-Oscillators
Authors: Bhushan A. , Inamdar M. M. , Pawaskar D. N.
Published: January 2015

Frequency stability is a desirable property for micro- and nanoelectromechanical system oscillators used in reference and timing applications. In case of doubly-clamped oscillators, resonant frequencies are highly sensitive to the operating temperature because of development of internal stresses due to thermal expansion under the restraint of fixed boundary conditions. In this paper, we present a design procedure to reduce the variation of resonant frequency with respect to change in operating temperature, in other words improve the frequency stability, by exploiting the interaction between electrostatic and geometric nonlinearities in electrostatically actuated doubly-clamped nano-oscillators. We have modeled the nano-oscillators using Euler-Bernoulli beam theory and Galerkin based reduced order modeling technique. We have examined first natural frequency variation due to temperature change for different carbon nanotube oscillators and an optimization based design procedure has been devised for improving the frequency stability.
Enhancing Damage Identification Robustness to Noise and Damping Using Integrated Bistable and Adaptive Piezoelectric Circuitry
Authors: Kim Jinki , Harne R. L. , Wang K. W.
Published: January 2015

The accurate and reliable identification of damage in modern engineered structures is essential for timely corrective measures. Vibration-based damage prediction has been studied extensively by virtue of its global damage detection ability and simplicity in practical implementation. However, due to noise and damping effects, the accuracy of this method is inhibited when direct peak detection (DPD) is utilized to determine resonant frequency shifts. This research investigates an alternative method to detect frequency shifts caused by structural damage based on the utilization of strongly nonlinear bifurcation phenomena in bistable electrical circuits coupled with piezoelectric transducers integrated with the structure. It is shown that frequency shift predictions by the proposed approach are significantly less susceptible to error than DPD when realistic noise and damping levels distort the shifting resonance peaks. As implemented alongside adaptive piezoelectric circuitry with tunable inductance, the new method yields damage location and severity identification that is significantly more robust and accurate than results obtained following the DPD approach.
Nonlinear Bi-Stable Vibration Energy Harvester at Work
Authors: Orfei Francesco , Neri Igor , Vocca Helios , Gammaitoni Luca
Published: January 2015

An extreme low power energy rectification, storage and management circuitry has been developed and used to power a small digital wireless sensor with a piezoelectric non-linear bi-stable vibration energy harvester for automotive application. All the system has been designed with off-the-shelf components and sends data in the 2.4 GHz band using an 802.15.4 compliant transceiver. An 802.15.4 to UART and UART to Bluetooth interface has been realized to send the data acquired by the sensor to a Smartphone.
Domain Composition Method for Structural Optimization
Authors: Song Wei , Gea Hae Chang , Zheng Bin
Published: January 2015

Conventionally, design domain of topology optimization is predefined and is not adjusted in the design optimization process since designers are required to specify the design domain in advance. However, it is difficult for a fixed design domain to satisfy design requirements such as domain sizing adjustment or boundaries change. In this paper, Domain Composition Method (DCM) for structural optimization is presented and it deals with the design domain adjustment and the material distribution optimization in one framework. Instead of treating design domain as a whole, DCM divides domain into several subdomains. Additional scaling factors and subdomain transformations are applied to describe changes between different designs. It then composites subdomains and solve it as a whole in the updated domain. Based on the domain composition, static analysis with DCM and sensitivity analysis are derived. Consequently, the design domain and the topology of the structure are optimized simultaneously. Finally, the effectiveness of the proposed DCM for structural optimization is demonstrated through different numerical examples.
Design of a Thermally Activated Energy Harvesting System
Authors: Toom Zachary , Quinn D. Dane
Published: January 2015

The design optimization of a thermally activated energy harvesting system is considered here. Shape Memory Alloy (SMA) components are used to transform the thermal excitation to mechanical vibrations, which harvested through electromechanical coupling into storable electrical energy. The frequency of the mechanical vibrations is subject to up-conversion through the use of bi-stable mechanical system, modeled as a buckled beam. As the SMA undergoes low-frequency thermal oscillations, the bi-stable mechanical system undergoes a snap-through response, so that the energy harvesting attachment exhibits a vibration frequency much higher than the underlying thermal vibrations, leading to an increase in the time-averaged power that can be harvested from the system. Through design optimization studies the system characteristics are chosen to maximize the average harvested power from this system.
Effects of Injection Moulding Parameters on Dimensional Accuracy of POM/MWCNT Micro Parts
Authors: Bellantone Vincenzo , Surace Rossella , Fassi Irene
Published: January 2015

Nowadays, the study of polymer nanocomposites is an active area of materials development because nanofillers and in particular Multi-Wall Carbon Nanotubes (MWCNTs) can significantly improve or adjust the properties of the materials into which they were incorporated such as optical, electrical, mechanical and thermal properties. MWCNTs have been adopted in quite a number of applications, but advancements in their properties are needed for spreading their potential. Moreover their behaviour and filling properties in micro injection moulding process have still to be studied.

Therefore, in this work, experimental and statistical studies were performed to analyze the parameters effect on replicating capability of micro parts manufactured in POM/MWCNT by micro injection moulding process. Two compounds with different filler fraction (3 and 6 wt%) were tested and processed with different conditions and their operating range have been pointed out and compared with that of pristine POM (PolyOxyMethilene).

The results show that the filler content has the effect to change slightly the operative range of the micro injection process parameters and to increase the replicating capability. The most effective parameters on replicating capability of micro ribs, evaluated by a dimensional index, are the mould temperature for the POM/MWCNT 3% and injection velocity for the 6% filler fraction.
Dual Residual in Augmented Lagrangian Coordination for Decomposition-Based Optimization
Authors: Xu Meng , Fadel Georges , Wiecek Margaret M.
Published: January 2015

As system design problems increase in complexity, researchers seek approaches to optimize such problems by coordinating the optimizations of decomposed sub-problems. Many methods for optimization by decomposition have been proposed in the literature among which, the Augmented Lagrangian Coordination (ALC) method has drawn much attention due to its efficiency and flexibility. The ALC method involves a quadratic penalty term, and the initial setting and update strategy of the penalty weight are critical to the performance of the ALC. The weight in the traditional weight update strategy always increases and previous research shows that an inappropriate initial value of the penalty weight may cause the method not to converge to optimal solutions.

Inspired by the research on Augmented Lagrangian Relaxation in the convex optimization area, a new weight update strategy in which the weight can either increase or decrease is introduced into engineering optimization. The derivation of the primal and dual residuals for optimization by decomposition is conducted as a first step. It shows that the traditional weight update strategy only considers the primal residual, which may result in a duality gap and cause a relatively big solution error. A new weight update strategy considering both the primal and dual residuals is developed which drives the dual residual to zero in the optimization process, thus guaranteeing the solution accuracy of the decomposed problem. Finally, the developed strategy is applied to both mathematical and engineering test problems and the results show significant improvements in solution accuracy. Additionally, the proposed approach makes the ALC method more robust since it allows the coordination to converge with an initial weight selected from a much wider range of possible values while the selection of initial weight is a big concern in the traditional weight update strategy.
Kinematic and Dynamic Evaluation of Mobile Robots Performing Welding Tasks
Authors: Canfield Stephen L. , Qualls Josh , Shibakov Alexander
Published: January 2015

As mobile robotic systems advance, they become viable technologies for automating manufacturing processes in fields that traditionally have not seen much automation. Such fields include shipbuilding, windmill, tank, and pipeline construction. Some of the manufacturing tasks in these fields require process validation prior to use in the manufacturing process. One such example process is welding. However, there is a lack of industry standards for mechanized or robotic welding that can impede the introduction of mobile robotic welding systems in the market place. There is also a lack of generalized fitness measures that gauge the suitability of mobile robot topologies or dimensional designs to a set of tasks and can be used in the design or verification process. This paper will consider the metrics that can be used in evaluating mobile robot designs for welding tasks based on kinematic and dynamic characteristics. The approach is based on a representation of the weld task and robot capabilities as a pair of n-dimensional subsets in the Euclidean n-space, where the weld task is considered a repetitive pattern constructed along the weld seam and both kinematic and dynamic characteristics are considered for the robot. The motivation is to allow different mobile manipulator designs to be measured using a direct geometric comparison of the capabilities of the robot to the requirements of the task. Three mobile welding platforms having different topological kinematic arrangements and will be evaluated based on this metric. This metric will further be shown to supplement the weld qualification process through verification of the motion control portions of the weld process based on a specific robot design. The method will contribute to the design and development of mobile robotic welding systems to become viable and accepted.
Modeling Laser Travel and its Effects on Temperature Evolution in Laser Hardening of Hypoeutectoid Steel
Authors: Ghosh Suhash , Sahay Chittaranjan
Published: January 2015

To achieve a precise and controlled laser process, a thorough analysis of the thermal behavior of the material is necessary. The knowledge of the thermal cycles is important to ascertain suitable processing parameters, thus improving surface properties when the alloys are laser irradiated. In the present paper, a numerical simulation of the laser hardening process has been developed using the finite element (FE) code ABAQUS™ to solve the heat transfer equation inside the treated material (AISI 4140 steel). The thermal analysis is based on Jaeger’s classical moving heat source method by considering the laser beam as a moving plane (band/disc) heat source and the target material is a semi-infinite solid. However, the FE model, used to solve the governing equation, does not directly accommodate the moving nature of heat source. A reasonable approximation is to divide the laser travel on the substrate into many small time/load steps, and apply variable flux and boundary conditions in each time/load step. This approximates the quasi-steady state phenomena over the series of these time steps for the complete laser travel. This paper investigates the effects of the choice of time/load steps on the temperature evolution as well the computing times in the process.
The Fuzzy Front End: Concept Development in the Automotive Industry
Authors: Elverum Christer W. , Welo Torgeir , Steinert Martin
Published: January 2015

The fuzzy front end (FFE) of new product development (NPD) is a term that refers to the early stages of the innovation process. This paper investigates the FFE in the automotive industry and addresses the challenges of working in this phase of the innovation process, as well as the academic definition of the FFE relative to the real world. Two parts of the innovation process have been identified and characterized as FFE: the concept-work within satellite front-end departments and the work within the pre-development phase of the vehicle new product development process. It has been identified that one of the greatest challenges related to working in the FFE is developing viable concepts that will “sell” internally. Estimating and conveying the overall value of the final product in terms of costs and customer benefits are two of the key elements that make it difficult to achieve internal “buy in”. Furthermore, it is argued that the most common academic perception of the FFE seem to be inadequate since it only concerns work that ends with a go/no-go decision whether to continue into development or not. Consequently, it fails to capture early-stage development work of transformational innovations, where the decision of development has already been made and the uncertainty is related to the execution of the work — and — not the outcome. Semi-structured interviews with a total of eleven employees at seven different automotive OEMs form the basis for the conclusions made herein.