bluuebunny/crossref_metadata_2025 huggingface dataset:
A Study of Fuzzy Hysteresis Modeling and Control of a Shape Memory Wire Actuator
Authors: Mehrabian Ali Reza , Hashemi S. Vahid , Williams Eric , Elahinia Mohammad
Published: May 2009

This paper describes the development of fuzzy systems for modeling the hysteresis behavior of shape memory alloy (SMA) actuators. Due to their simplicity and ease of actuation, SMA actuators are very attractive for applications such as miniature robots for micro manufacturing. However, SMAs have not been widely used for motion control applications due to their nonlinear behavior and control difficulties. One approach to design a position controller for SMA systems is to employ an inverse-model of the system in the control loop to compensate the hysteresis properties of the material. Fuzzy systems, due to their nonlinear learning and adaptation abilities, are good candidates for obtaining inverse-models. In this paper two fuzzy modeling approaches are employed and compared to develop a model for a SMA wire actuator. A set of experiments are conducted to generate the training data. The test stand includes a Nickel-Titanium (TiNi) SMA wire, a position sensor, a bias spring and a current amplifier. By comparing the performance of the two employed fuzzy modeling techniques, it is revealed that the approach based on fuzzy Gustafson-Kessel (GK) clustering shows a better performance in the modeling of the hysteresis in the SMA wire. Thus, GK clustering algorithm is employed to develop the inverse-model for the SMA. The reported results demonstrate the ability of the employed fuzzy algorithm for modeling the hysteresis in the system, and the merits of the introduced inverse-model in the control of the position of the SMA.
Multibody Molecular Dynamics I: Theoretical Development
Authors: Mukherjee Rudranarayan M. , Anderson Kurt S.
Published: May 2009

This is the first paper in a series of two papers on using multibody dynamics algorithms and methods for coarse-grained molecular dynamics simulations. This paper presents the underlying framework for multi-scale modelling of biomolecules and polymers. In this framework, the system to be simulated is sub-structured into a hierarchy of multi-resolution models that are simulated using efficient multibody dynamics algorithms. The algorithms work in a unified framework, enabling efficient multi-scale (or multi-resolution) simulations. A discussion of the hierarchy of models with different resolutions along with the salient features of the appropriate multibody dynamics algorithms used for simulating them is presented. The unified scheme and the qualitative advantages of the method are discussed. Important implementation details such as boundary conditions, temporal integration schemes, interaction force field calculations and solvent models are also presented. In the next paper applications and results are discussed.
Conjoint-HoQ: A Quantitative Methodology for Consumer-Driven Design
Authors: Olewnik Andrew T. , Lewis Kemper E.
Published: May 2009

This paper presents a methodology, Conjoint-HoQ, which is meant to provide an improvement over the current House of Quality (HoQ) tool. The improvement comes in the form of quantitative technical information — replacing the qualitative nature of the current HoQ — through integration of conjoint analysis into the HoQ framework. The steps of the Conjoint-HoQ method are presented in detail with an accompanying hypothetical example, the design of a hair dryer. A number of research issues critical to implementation in industry are also identified and discussed. The resulting methodology is representative of design tools seen as vital to supporting the emerging paradigm of mass-customization.
Mitigation of Ship Motion Using Passive and Active Anti-Roll Tanks
Authors: Marzouk Osama A. , Nayfeh Ali H.
Published: May 2009

Because excessive roll motions of ships in rough seas badly affect their performance, there is a continuous interest in efficient ways to mitigate these undesirable motions. There are different devices to mitigate the roll of ships with different levels of performance and operating limits. Anti-roll tanks are more effective than other roll stabilization devices when the ship is not underway or moves slowly. Here, we investigate the application of passive and active anti-roll tank systems. The tank system consists of three tanks: each one consists of two columns connected at the bottom via a horizontal pipe equipped with a pump. The tanks are arranged along the length of the ship, symmetrically located about its center of gravity. The motion of the liquid in the tank is 1-D, but it exerts loads on all degrees of freedom of the ship. The equation governing the tank-liquid motion is coupled with the equations governing the 6-DOF motion of the ship in waves; the coupled system is solved simultaneously in time. First, we derive expressions for the forces and moments exerted on the ship by the tanks. Then, we study the roll response at different sea heading angles in rough sea conditions in the absence of the tanks to identify the critical heading angles where the roll is large. We demonstrate the nonlinear behavior of roll through frequency-response curves for different beam wave amplitudes. These curves exhibit typical nonlinear phenomena (jumps and hysteresis) for high wave amplitudes. Spectral analysis shows a two-to-one frequency relationship between the roll and pitch in rough head and follower seas, which are the most critical sea headings. For passive and active tanks, we study the effect of the frequency of the tank system on its effectiveness. We consider active anti-roll tanks in which the pump power is controlled via a proportional-derivative (PD) control law using the roll angle and its rate. We compare the performances of passive and active tanks in rough sea for the critical heading angles. We found that active anti-roll tanks outperform passive ones in terms of roll reduction and size and weight, but they require power consumption. To achieve a specified roll reduction, the weight of a passive tank might be as large as five times that of an active tank. We also found that the performance of passive tanks depends strongly on their frequencies, in contrast with active tanks, which are insensitive to their frequencies.
Preference Inconsistency in Multidisciplinary Design Decision Making
Authors: MacDonald Erin , Gonzalez Richard , Papalambros Panos
Published: May 2009

Research from behavioral psychology and experimental economics asserts that individuals construct preferences on a case-by-case basis when called to make a decision. A common, implicit assumption in engineering design is that user preferences exist a priori. Thus, preference elicitation methods used in design decision making can lead to preference inconsistencies across elicitation scenarios. This paper offers a framework for understanding preference inconsistencies, within and across individual users. We give examples of three components of this new framework: comparative, internal, and external inconsistencies across users. The examples demonstrate the impact of inconsistent preference construction on common engineering and marketing design methods, including discrete choice analysis, modeling stated vs. revealed preferences, and the Kano method and thus QFD. Exploring and explaining preference inconsistencies produces new understandings of the relationship between user and product.
Analytical Investigation of Radiated Noise for a Shaft-Bearing-Plate System Due to the Excitation of Helical Gears
Authors: Park Chan Il
Published: May 2009

Helical gears excite their housing system through forces and moments of bearings and then radiate noise. If noise is to be reduced, the contribution of noise to the gear housing due to the force and the moment must be determined. This work analytically investigated the radiated noise of a helical gear-housing system due to the excitation of helical gears. The helical gear-housing system consisted of gears, shafts, bearings, housings, and accessories. The gears were modeled as a 12-degree of freedom mass-spring-damper system; the shaft was modeled as a rod, a beam, and a torsional shaft so that the force and the moment were transmitted; and the gear housing was modeled as a clamped circular plate with viscous damping. The modeling of this system used transfer matrices for helical gears, shafts, and bearings. Damping for both the bearings and the plate were obtained by modal testing. An analysis of forced vibration of assembled transfer matrices produced a transmission of vibration. For the evaluation of noise, sound pressure from the plate due to the force and the moment in both radial and tangential directions was analytically derived by the Rayleigh integral. The analytical derivation and parameters from the experiment were applied to an analysis of noise for the two sets of helical gears with differing gear ratios. The analysis showed that the moment excitation in both helical gears contributed more to the noise of the plate than axial force excitation.
Repetitive Contact Imaging
Authors: Zhao Haiyu , Rahn Christopher D.
Published: May 2009

Repetitive contact imaging uses a flexible whisker attached to a two axis robot to measure the shape of contacted objects. Assuming small deformations and rotations, the pitch axis decouples from yaw. The yaw axis, under PD control, sweeps periodically back and forth across the object while the pitch axis, under repetitive learning (RL) control, maintains a uniform contact force using load cell and encoder feedback. Once the RL controller converges, the 3D contact points can be determined using an elastica algorithm. The RL controller is proven stable based on a distributed parameter beam model and experimentally shown to provide stable performance with improved moment regulation when compared to PD control.
Complementary Interaction Method (CIM) for System Reliability Analysis
Authors: Youn Byeng D. , Wang Pingfeng , Xi Zhimin , Gorsich David J.
Published: May 2009

Researchers desire to evaluate system reliability uniquely and efficiently. Despite years of research, little progress has been made on system reliability analysis. Up to now, bound methods for system reliability prediction have been dominant. For system reliability bounds, the probabilities of the second or higher order joint events are assumed to be known exactly although there is no numerical method to evaluate them effectively. Two primary challenges in system reliability analysis are how to evaluate the probabilities of the second or higher order joint events and how to uniquely obtain the system reliability so that the system reliability can be used for Reliability-Based Design Optimization (RBDO). This paper proposes the Complementary Interaction Method (CIM) to define system reliability in terms of the probabilities of the component events, Ei = (X |Gi ≤ 0), and the complementary interaction events, Eij = (X |Gi*Gj ≤ 0). For large-scale systems, the probabilities of the component and complementary interaction events can be conveniently written in the CI-matrix. In this paper, three different reliability methods will be used to construct the CI-matrix numerically: First-Order Reliability Method (FORM), Second-Order Reliability Method (SORM), and the Eigenvector Dimension Reduction (EDR) method. Two examples will be employed to demonstrate that the CIM with the EDR method outperforms other methods for system reliability analysis in terms of efficiency and accuracy.
On the Equivalence of Normal Form Theory and Multiple Time Scale Method
Authors: Wang Fengxia , Bajaj Anil K.
Published: May 2009

Multiple time scales technique has long been an important method for the analysis of weakly nonlinear systems. In this technique, a set of multiple time scales are introduced that serve as the independent variables. The evolution of state variables at slower time scales is then determined so as to make the expansions for solutions in a perturbation scheme uniform in natural and slower times. Normal form theory has also recently been used to approximate the dynamics of weakly nonlinear systems. This theory provides a way of finding a coordinate system in which the dynamical system takes the “simplest” form. This is achieved by constructing a series of near-identity nonlinear transformations that make the nonlinear systems as simple as possible. The “simplest” differential equations obtained by the normal form theory are topologically equivalent to the original systems. Both methods can be interpreted as nonlinear perturbations of linear differential equations. In this work, the equivalence of these two methods for constructing periodic solutions is proven, and it is explained why some studies have found the results obtained by the two techniques to be inconsistent.
Predictive Carbon Nanotube Models Using the Eigenvector Dimension Reduction (EDR) Method
Authors: Xi Zhimin , Youn Byeng D.
Published: May 2009

It has been reported that a carbon nanotube (CNT) is one of the strongest materials with their high failure stress and strain. Moreover, the nanotube has many favorable features, such as high toughness, great flexibility, low density, and so on. This discovery has opened new opportunities in various engineering applications, for example, a nanocomposite material design. However, recent studies have found a substantial discrepancy between computational and experimental material property predictions, in part due to defects in the fabricated nanotubes. It is found that the nanotubes are highly defective in many different formations (e.g., vacancy, dislocation, chemical, and topological defects). Recent parametric studies with vacancy defects have found that the vacancy defects substantially affect mechanical properties of the nanotubes. Given random existence of the nanotube defects, the material properties of the nanotubes can be better understood through statistical modeling of the defects. This paper presents predictive CNT models, which enable to estimate mechanical properties of the CNTs and the nanocomposites under various sources of uncertainties. As the first step, the density and location of vacancy defects will be randomly modeled to predict mechanical properties. It has been reported that the Eigenvector Dimension Reduction (EDR) method performs probability analysis efficiently and accurately. In this paper, Molecular Dynamics (MD) simulation with a modified Morse potential model is integrated with the EDR method to predict the mechanical properties of the CNTs. To demonstrate the feasibility of the predicted model, probabilistic behavior of mechanical properties (e.g., failure stress, failure strain, and toughness) is compared with the precedent experiment results.
A Single-Stage Gradient-Based Approach for Solving the Joint Product Family Platform Selection and Design Problem Using Decomposition
Authors: Khajavirad Aida , Michalek Jeremy J.
Published: May 2009

A core challenge in product family optimization is to develop a single-stage approach that can optimally select the set of variables to be shared in the platform(s) while simultaneously designing the platform(s) and variants within an algorithm that is efficient and scalable. However, solving the joint product family platform selection and design problem involves significant complexity and computational cost, so most prior methods have narrowed the scope by treating the platform as fixed or have relied on stochastic algorithms or heuristic two-stage approaches that may sacrifice optimality. In this paper, we propose a single-stage approach for optimizing the joint problem using gradient-based methods. The combinatorial platform-selection variables are relaxed to the continuous space by applying the commonality index and consistency relaxation function introduced in a companion paper. In order to improve scalability properties, we exploit the structure of the product family problem and decompose the joint product family optimization problem into a two-level optimization problem using analytical target cascading so that the system-level problem determines the optimal platform configuration while each subsystem optimizes a single product in the family. Finally, we demonstrate the approach through optimization of a family of ten bathroom scales; Results indicate encouraging success with scalability and computational expense.
Optimal, Model-Based Design of Soft Robotic Manipulators
Authors: Trivedi Deepak , Dienno Dustin , Rahn Christopher D.
Published: May 2009

Soft robotic manipulators, unlike their rigid-linked counterparts, deform continuously along their lengths similar to elephant trunks and octopus arms. Their excellent dexterity enables them to navigate through unstructured and cluttered environments and handle fragile objects using whole arm manipulation. Soft robotic manipulator design involves the specification of air muscle actuators and the number, length and configuration of sections that maximize dexterity and load capacity for a given maximum actuation pressure. This paper uses nonlinear models of the actuators and arm structure to optimally design soft robotic manipulators. The manipulator model is based on Cosserat rod theory, accounts for large curvatures, extensions, and shear strains, and is coupled to nonlinear Mooney-Rivlin actuator model. Given a dexterity constraint for each section, a genetic algorithm-based optimizer maximizes the arm load capacity by varying the actuator and section dimensions. The method generates design rules that simplify the optimization process. These rules are then applied to the design of pneumatically and hydraulically actuated soft robotic manipulators, using 100 psi and 1000 psi maximum pressure, respectively.
Multi-Objective Optimization of Compliant Mechanisms Including Failure Theories
Authors: Canfield Stephen L. , Chlarson Daniel L. , Shibakov Alexander , Richardson Joseph D. , Saxena Anupam
Published: May 2009

This paper will present a version of failure theory suitable for designing optimal compliant mechanisms. The resulting theory will be incorporated as design objective functions within a multi-objective optimizing engine with the purpose of producing optimal and robust compliant mechanisms suitable for manufacture. Combining these failure-based objective functions with the classical ones measuring efficiency in performing a task, in the context of diversity promoting multiobjective optimization (see [1]) will demonstrate the tool’s ability to produce optimal compliant mechanisms that are failure-proof as well as provide insights into the complexity of particular design problems.
Application Criteria for Conserving Integrators and Projection Methods in Multibody Dynamics
Authors: Dopico Daniel , Cuadrado Javier , Garcia Orden Juan C. , Luaces Alberto
Published: May 2009

This work presents the application to the dynamics of multibody systems of two methods based on augmented Lagrangian techniques, compares them, and gives some criteria for its use in realistic problems. The methods are an augmented Lagrangian method with orthogonal projections of velocities and accelerations, and an augmented Lagrangian energy conserving method. Both methods were presented by the authors in a very recent work, but it was not complete since the testing and the comparison of the methods was done by simulating a simple and academic example, and that was not sufficient to draw conclusions in terms of efficiency. For this work, the whole model of a vehicle has been simulated through both formulations, and their performance compared for such a large and realistic problem.
A Dynamic 3D Geometry Compression Scheme Based on the Lifted Wavelet Transform
Authors: Dekkar Malic , Wang Yan
Published: May 2009

In distributed environments, efficient visual information sharing is critical for effective communication in real-time engineering collaboration. Methods of geometry compression are needed for high-volume geometry data distribution over networks with limited bandwidths and heterogeneous storage capacities. In this paper, a new compression scheme for time-varying 3D geometry is introduced to support engineering and scientific visualization while showing potential for the audiovisual presentation and entertainment fields. This hybrid approach allows geometric and topological information to be uniformly encoded as volume grid values then compressed based on the lifted wavelet transform. The compression ratio is significantly increased without compromising surface quality due to rescaling and integer-to-integer lifting. This approach also allows for scalability in terms of additional data streams such as color, audio, and other types of concurrent data necessary for the desired customization of this method.
Discrete-Time Robust Control of Linear Periodically Time-Varying Systems
Authors: Kalender S. , Flashner H.
Published: May 2009

An approach for robust control of periodically time-varying systems is proposed. The approach combines the point-mapping formulation and a parameterization of the control vector to formulate an equivalent time-invariant discrete-time representation of the system. The discrete-time representation of the dynamic system allows for the application of known sampled-data control design methodologies. A perturbed, discrete-time dynamic model is formulated and plant parametric uncertainty are obtained using a truncated point-mapping algorithm. The error bounds due to point-mapping approximation are computed and a robustness analysis problem of the system due to parametric uncertainties is formulated using structured singular value theory. The proposed approach is illustrated by two design examples. Simulation studies show good performance robustness of the control system to parameter perturbations and system nonlinearities.
Evaluation Method of Drinking Ease for Aluminum Beverage Bottles
Authors: Yamazaki Koetsu , Chihara Takanori , Itoh Ryoichi , Han Jing , Nishiyama Sadao
Published: May 2009

This paper has investigated effects of the bottle opening size on drinking feelings in order to improve the comfort level of consumers when drinking directly from the opening of aluminum bottle. A survey over 120 subjects has been performed based on a drinking test using three kinds of bottles with opening diameters of 28, 33 and 38 mm, respectively. Two questionnaires have been conducted. Statistical analysis results of Questionnaire 1 have shown that 33-mm opening is best for adult consumers with no matter the type of contents, gender and the mouth size. The factor analysis results of Questionnaire 2 based on Kansei Engineering have shown that drinking feeling is affected by two common factors, which considered as the flow from the bottle to the mouth and the flow adjustability. Moreover, the fluid-dynamics analysis model has been developed to simulate the bottled liquid in a drinking action consisting of survey results and experimental observations of consumers’ drinking actions. Numerical simulations have been performed to understand how consumers control the flow during the drinking actions. It is found that the consumers usually try to realize the ideal and preferable condition by adjusting the inclination angle of the bottle.
Decision Retrieval and Storage Enabled Through Description Logic
Authors: Mocko Gregory M. , Rosen David W. , Mistree Farrokh
Published: May 2009

The problem addressed in the paper is how to represent the knowledge associated with design decision models to enable storage, retrieval, and reuse. The paper concerns the representations and reasoning mechanisms needed to construct decision models of relevance to engineered product development. Specifically, AL[E][N] description logic is proposed as a formalism for modeling engineering knowledge and for enabling retrieval and reuse of archived models. Classification hierarchies are constructed using subsumption in DL. Retrieval of archived models is supported using subsumption and query concepts. In our methodology, design decision models are constructed using the base vocabulary and reuse is supported through reasoning and retrieval capabilities. Application of the knowledge representation for the design of a cantilever beam is demonstrated.
Modeling and Torsional Vibration Analysis of Engine Cold-Test Stand Drivelines
Authors: Gul Kamran A. , Adams Douglas E.
Published: May 2009

Many large-scale engine manufacturers use cold-testing techniques to test engine assemblies for measuring transmission noise and diagnosing cylinder faults, valve-train and oil pump defects, which cannot be detected easily using traditional hot testing. Cold-testing is done by rotating the unfired engines by an external electrical drive and a driveline and analyzing the measured torque signal characteristics at various engine speeds. In this work, two different cold-test stands, which experience large torsional oscillations excited by various engine harmonics, are modeled. The excessive vibratory response of these stands not only makes the engine fault detection process difficult by degrading the measured torque signal, but can also cause structural failure. An appropriate driveline design is required to decrease the torsional vibration and noise levels and preserve the integrity of diagnostic signals. In an effort to prevent undesirable noise and vibration problems, models of engine cold-test stands are developed that involve modeling of driveline components, engine excitation model for cold-testing, and estimation of torsional vibratory response. The developed models are validated by comparing the model predictions with experimental responses. Model parameters that can help suppress the torsional resonances are determined using embedded sensitivity functions. It is shown that using a smaller-sized motor and a softer rubber coupling, the driveline torsional resonant frequencies excited during the speed sweep can be shifted out of the test range and the amplitudes can be decreased. The developed model is, therefore, used to help redesign the cold-test stand drivelines.
Development of Texture Design System Using Fractal and 1/f Fluctuation
Authors: Nakatsuka Satoshi , Aoyama Hideki
Published: May 2009

To enhance product added-value, there is an increasing trend recently to print wood grain patterns or give texture to building materials and industrial products by surface treatment. Surface treatment is not only applied for decorative purposes but it also serves practical purposes such as hiding surface damage and uneven coating invisible. The methods of designing wood grain and texture on surface are presently limited to the following three: 1) Copying the surface of natural objects, 2) designed by professional designers, and 3) outputting algorithms from computer. The first method by copy can create natural design but is not unique. The second method is difficult when there is a need to create various designs since this method requires considerable time and cost. And the last method by computer is able to output consistent designs but can not generate design expressing natural impression. The goal of this study was to develop a system for designing unique, natural, and diverse product surface textures using computer algorithms, To realize these three features, the system was designed to apply “fractal” and “1/f fluctuation”, which are inherent in the natural world. A basic form of texture is constructed as “fractal”, which can generate endless varieties of form, and “1/f fluctuation” is added to the basic texture to provide a natural feel. The system allows everyone from the layman to experts to design such textures easily using a developed user-intuitive interface, and check texture form in real time. From this system, a variety of textures, from consistent design to natural design, can be generated from different patterns of parameters such as “fractal” and “1/f fluctuation”.
Fabrication of High Density Silicon Nano-Dots by Excimer Laser Irradiation on Block Copolymer Masks
Authors: Ahn Dae Up , Sancaktar Erol
Published: May 2009

We report easy and fast fabrication methods to prepare densely packed polystyrene (PS) and silicon nano-dots using one-step excimer laser irradiation on cylindrically nanopatterned block copolymer materials, without any additional selective etching steps before a non-selective etching. Preferential etching in more ultraviolet (UV)-sensitive block component, and non-selective removal of all block components allowed transferring nanopatterns in block copolymer masks to inorganic silicon substrates, when an appropriate laser intensity was used. Surface melt flows of block components, which severely undermine the initial orders of nanopatterns in a block copolymer mask, were observed at the laser intensity near the ablation threshold of the less UV-sensitive component. Thus, in order to obtain mask-image-like topographic nanopatterns on the target material surfaces, the intensity of excimer laser radiation should be sufficiently lower than the ablation threshold of the less UV-sensitive component as long as the intensity is higher than that of the more UV-sensitive component. Numerical analyses on the photothermal excimer laser ablation in binary mixture systems predicted the presence of a matrix-assisted excimer laser ablation in the less UV-sensitive component at the laser intensity lower than its ablation threshold, owing to the heat conduction from the more UV-sensitive component during the nanoscopic level of time duration.
A State-Variable Decomposition Method for Estimating Modal Parameters
Authors: Feeny B. F. , Farooq U.
Published: May 2009

A nonsymmetric, generalized eigenvalue problem is constructed from state-variable ensembles. The data-based eigenvalue problem is related to the state-variable formulation of linear multi-degree-of-freedom systems. The inverse-transpose of the eigenvector matrix from this eigenvalue problem converges to the state-variable modal eigenvectors, and the eigenvalues lead to estimates of frequencies and modal damping. The interpretation holds whether damping is modal or nonmodal, and without the need of input data. The method is illustrated on an eight degree-of-freedom mass-spring-dashpot example.
Towards a Format Registry for Engineering Data
Authors: Grauer Michael J. , Howley Iris K. , Kopena Joseph B. , Regli William C.
Published: May 2009

There has been a great deal of interest recently in the problem of long term archiving of digital data. This is especially so in engineering design, where the CAD software tools evolve rapidly but the manufactured products themselves have much longer lifetimes whose support requires archived design data in a usable form. The ISO Open Archival Information Systems (OAIS) Reference Model is a widely used standard for digital archiving, with an essential piece of this model being a file format registry. A file format registry is a system for housing information about file formats that allows for correct interpretation, rendering, storage, and translation of digital files. Currently there exists no file format registry specifically for CAD file formats. This paper explains the purpose of a file format registry for CAD in the greater context of digital archiving, and then presents our approach to creating a CAD file format registry using the Resource Description Framework (RDF) language of the Semantic Web. By creating our file format registry in RDF, we allow archival systems to perform automated reasoning on the stored files. We hope that this paper will increase awareness of this element of engineering design repositories in the research community of this conference.
Flight Dynamics and Simulation of Laser Propelled Lightcraft
Authors: Ballard Christopher G. , Anderson Kurt S. , Myrabo Leik N.
Published: May 2009

A seven degree-of-freedom (DOF) dynamic model was developed to provide insight into the flight behavior of Type 200 and other related Lightcraft, and to serve as a research tool for developing future engine-vehicle configurations for laser launching of nano-satellites (1–10+ kg). Accurate engine, beam, and aerodynamics models are included to improve the predictive capability of the 7-DOF code. The aerodynamic forces of lift, drag, and aerodynamic pitching moment were derived from Fluent computational fluid dynamics predictions, and calibrated against limited existing wind tunnel data. To facilitate 7-DOF model validation, simulation results are compared with video analysis of actual flights under comparable conditions. Despite current limitatations of the 7-DOF model, the results compared well with experimental flight trajectory data.
Adaptive Slicing of Moving Least Squares Surfaces: Toward Direct Manufacturing of Point Set Surfaces
Authors: Yang Pinghai , Qian Xiaoping
Published: May 2009

Rapid advancement of 3D sensing techniques has lead to dense and accurate point cloud of an object to be readily available. The growing use of such scanned point sets in product design, analysis and manufacturing necessitates research on direct processing of point set surfaces. In this paper, we present an approach that enables the direct layered manufacturing of point set surfaces. This new approach is based on adaptive slicing of moving least squares (MLS) surfaces. Salient features of this new approach include: 1) it bypasses the laborious surface reconstruction and avoids model conversion induced accuracy loss; 2) the resulting layer thickness and layer contours are adaptive to local curvature and thus it leads to better surface quality and more efficient fabrication; 3) the MLS surface naturally smoothes the point cloud and allows up-sampling and down-sampling, and thus it is robust even for noisy or sparse point sets. Experimental results of the slicing algorithm on both synthetic and scanned point sets are presented.
A Discussion of Low Order Numerical Integration Formulas for Rigid and Flexible Multibody Dynamics
Authors: Khude Naresh , Jay Laurent O. , Schaffer Andrei , Negrut Dan
Published: May 2009

The premise of this work is that real-life mechanical systems limit the use of high order integration formulas due to the presence in the associated models of friction and contact/impact elements. In such cases producing a numerical solution necessarily relies on low order integration formulas. The resulting algorithms are generally robust and expeditious; their major drawback remains that they typically require small integration step-sizes in order to meet a user prescribed accuracy. This paper looks at three low order numerical integration formulas: Newmark, HHT, and BDF of order two. These formulas are used in two contexts. A first set of three methods is obtained by considering a direct index-3 discretization approach that solves for the equations of motion and imposes the position kinematic constraints. The second batch of three additional methods draws on the HHT and BDF integration formulas and considers in addition to the equations of motion both the position and velocity kinematic constraint equations. The first objective of this paper is to review the theoretical results available in the literature regarding the stability and convergence properties of these low order methods when applied in the context of multibody dynamics simulation. When no theoretical results are available, numerical experiments are carried out to gauge order behavior. The second objective is to perform a set of numerical experiments to compare these six methods in terms of several metrics: (a) efficiency, (b) velocity constraint drift, and (c) energy preservation. A set of simple mechanical systems is used for this purpose: a double pendulum, a slider crank with rigid bodies, and a slider crank with a flexible body represented in the floating frame of reference formulation.
An Investigation of the Impact of Assembly Sequencing on the Product Family Design Outcomes
Authors: Tauhid Shafin , Artar Hakan U. , Gupta Saraj , Okudan Gu¨l
Published: May 2009

While many approaches have been proposed to optimize the product family design for measures of cost, revenue and performance, many of these approaches fail to incorporate the complexity of the manufacturing issues into family design decision-making. One of these issues is assembly sequencing. This paper presents a simulation study by which the impact of assembly sequencing on the product family design outcomes is investigated. Overall, the results indicate that when the product family design takes into account the assembly sequencing decisions, the outcomes at the shop floor level improve. The results have implications for companies that are looking into increasing their revenue without increasing their investment in the shop floor.
Assessment of Learning and Its Retention in the Engineering Design Classroom: Part B — Instrument Application
Authors: Okudan Gu¨l , Ogot Madara , Gupta Saraj
Published: May 2009

This paper describes the application of the instrument developed to measure engineering design knowledge gain as a result of a course. The goal for the development of the instrument was the need for an assessment instrument that will be a stable measure of the impact of pedagogic improvements and introduction of new supporting material in the classroom environment. Our ultimate goal is to prepare the environmental conditions and course material that are most conducive for our students in teaching engineering design courses. This paper documents the application process and the results.
Managing Design Process Complexity: A Value-of-Information Based Approach for Scale and Decision Decoupling
Authors: Panchal Jitesh H. , Paredis Christiaan J. J. , Allen Janet K. , Mistree Farrokh
Published: May 2009

Design processes for multiscale, multifunctional systems are inherently complex due to the interactions between scales, functional requirements, and the resulting design decisions. While complex design processes that consider all interactions lead to better designs; simpler design processes where some interactions are ignored are faster and resource efficient. In order to determine the right level of simplification of design processes, designers are faced with the following questions: a) how should complex design-processes be simplified without affecting the resulting product performance? and b) how can designers quantify and evaluate the appropriateness of different design process alternatives? In this paper, the first question is addressed by introducing a method for determining the appropriate level of simplification of design processes — specifically through decoupling of scales and decisions in a multiscale problem. The method is based on three constructs: interaction patterns to model design processes, intervals to model uncertainty resulting from decoupling of scales and decisions, and value of information based metrics to measure the impact of simplification on the final design outcome. The second question is addressed by introducing a value-of-information based metric called improvement potential for quantifying the appropriateness of design process alternatives from the standpoint of product design requirements. The metric embodies quantitatively the potential for improvement in the achievement of product requirements by adding more information for design decision making. The method is illustrated via a datacenter cooling system design example.
On the Effect of Cardboard Liners on Impact-Induced High Frequency Vehicular Driveline Vibrations
Authors: Theodossiades Stephanos , Rahnejat Homer , Kelly Patrick
Published: May 2009

A typical driveline Noise, Vibration and Harshness (NVH) spectrum contains the contribution of a significant number of vibration components, ranging from a few Hz to several kHz. This is due to different NVH phenomena that have their causes in the contact behaviour of discrete driveline components. A short duration, audible, high frequency, elastoacoustic phenomenon, which occurs as a load reversal in the presence of lashes in the driveline, is onomatopoeically known in industry as clonk (300–5,000 Hz). Its short duration acts as an impulse that excites a large number of structural modes of the lightly damped driveline system. The above phenomenon has become a major concern to automobile manufacturers in recent years with the modern trend of reducing inertial effects in powertrain systems by use of materials of lower elastic moduli and thinner sections. The most common approach in industry to reduce the radiated clonk noise is by using palliatives, such as metallic wires, foam-filled driveshafts, the Dual Mass Flywheel (DMF) and cardboard liners. However, the mechanisms of vibration and noise reduction that the above palliatives introduce have not been fully understood yet, as these are rather used in an empirical manner. This paper investigates the effect of cardboard liners on the high frequency driveline response, by a combined study of FEA analysis at component level and experimental measurements in a drivetrain rig. The results reveal that cardboard liners reduce the severity of the driveline high frequency vibrations, as well as the number of the driveshafts’ structural modes that are excited by remote impacting of the drivetrain components through their lash zones. The predicted and observed effect of the cardboard liners shows good conformance with the existing literature.
Finite Element Analysis Using Non-Conforming Mesh
Authors: Kumar Ashok V. , Burla Ravi , Padmanabhan Sanjeev , Gu Linxia
Published: May 2009

A method for engineering analysis using a regular or structured grid is described which does not require a conforming mesh to approximate the geometry of the analysis domain. The geometry of the domain is represented using implicit equations and a structured grid is used to approximate the solution. Solution structures are constructed using implicit equations such that the essential boundary conditions are satisfied exactly. The use of structured grid eliminates the need to generate a conforming mesh and thus reduces time taken to create models for analysis. This approach is used to solve boundary value problems arising in thermal and structural analysis. Convergence analysis is performed for several numerical examples and the results are compared with analytical and finite element analysis solutions to show that the method gives solutions that are similar to the finite element method in quality but is often less computationally expensive.
Scan and Solve: Acquiring the Physics of Artifacts
Authors: Freytag Michael K. , Shapiro Vadim , Tsukanov Igor
Published: May 2009

Existing physical artifacts including sculpture, mechanical parts, and anatomical structures are commonly acquired by modern surface and volumetric scanning technologies for archival, visualization, and diagnostic purposes. While the native representations for such data are largely sufficient for visualization purposes, more advanced field simulation currently requires extensive manual conversions into simplified surface and volume meshes compatible with the traditional finite element analysis pipeline. These conversions are tedious, error-prone, and require expertise in the mesh construction process. We demonstrate automated field simulation on acquired artifacts, bypassing the difficult geometric and topological meshing problems through a meshfree paradigm based on approximate distance fields computed from the native acquired data through sampling.
Attenuation of Continuous Vibration Transmission in the Hand and Arm Using Composite-Based Tool Designs
Authors: Brisach Daniel , Griffith Matthew , Konchar Janelle , Petfield Stephen , Popper Peter , Glancey James
Published: May 2009

Exposure to high noise levels may be the most common occupational hazard. Recent estimates suggest that as many as 30 million Americans are exposed to noise levels greater than the current safe limits for workplaces. At current durations of exposure, it is expected that 25% of these workers will develop permanent, noise-induced hearing loss. In many of these industrial environments, high levels of vibration also exist that can lead to several injuries and ailments. To address the adverse effects associated with the use of high noise emission impact tools, a study was initiated to develop and evaluate alternate tool designs that reduce the potential for hearing loss and vibration-related injuries. Recent work has focused on integrating advanced engineering polymers (composites) into tool designs for the purpose of eliminating direct metal-to-metal impact. This approach has several significant performance advantages including reduced operator discomfort due to hand-arm mechanical shock, reduced noise, and less danger from flying metal fragments. To quantify sound emission characteristics of these new designs, continuous sound pressure, maximum sound pressure, and maximum sound pressure level were measured using an array of five precision microphones each located 1 meter from the tool. Data was sampled at 40 kHz while test subjects operate both pneumatic tools and hand-struck tools. Frequency spectra of the sound pressure signals were examined for all tool treatments, and indicate that the addition of a polymer insert between metal impact components significantly reduces noise emission, especially at higher frequencies. Sound pressure levels were reduced by as much as 4 dBA compared to conventional tool designs. Similar reductions were observed in vibration transmission in the hand and arm. As a result, tools that integrate polymer-based components may be operated for longer daily exposure times without inducing hearing loss or vibration-related injuries. Data from this study may also help auditory and ergonomic specialists in understanding impulse noise characteristics and exposure.
Identification and Performance Prediction of Nonlinear Degrading Structures
Authors: Ajavakom Nopdanai , Ng Ching H. , Ma Fai
Published: May 2009

The lack of a fundamental theory of hysteresis is a major barrier to successful design of structures against deterioration associated with earthquakes, high winds, and sea waves. Development of a practical model of degrading structures that would match experimental observations is an important task. This paper has a two-fold objective. First, a superior system identification algorithm is devised to estimate the unspecified parameters in a differential model of hysteresis from experimental load-displacement traces. This algorithm is based upon the latest theory of genetic evolution and it will be streamlined through global sensitivity analysis. Second, the utility of identification of hysteresis is demonstrated through nonlinear response prediction, which is important in structural design. Suppose a hysteretic model is generated with a given load-displacement trace. It will be shown experimentally that the model will predict the response of the same system driven by other cyclic loads. The requirements for accurate prediction will be addressed. Through identification of hysteresis, it becomes possible to assess the performance of a real-life structure that has previously been damaged. In the open literature, there is not any other method that can perform the same task.
Feedback Control Via Eigenvalue Assignment for Time Delayed Systems Using the Lambert W Function
Authors: Yi Sun , Nelson Patrick W. , Ulsoy A. Galip
Published: May 2009

In this paper, we consider the problem of feedback controller design via eigenvalue assignment for systems of linear delay differential equations (DDEs). Unlike ordinary differential equations (ODEs), DDEs have an infinite eigenspectrum and it is not feasible to assign all closed-loop eigenvalues. However, we can assign a critical subset of them using a solution to linear DDEs in terms of the matrix Lambert W function. The solution has an analytical form expressed in terms of the parameters of the DDE, and is similar to the state transition matrix in linear ODEs. Hence, one can extend controller design methods developed based upon the solution form of ODEs to systems of DDEs, including the design of feedback controllers via eigenvalue assignment. We present such an approach here, illustrate using some examples, and compare with other existing methods.