bluuebunny/crossref_metadata_2025 huggingface dataset:
Optimal Control of Piezoelectric Laminated Parabolic Cylindrical Panels
Authors: Hu S. D. , Li H. , Tzou H. S.
Published: February 2014

Vibration control of parabolic cylindrical shell panels by piezoelectric patches using optimal control algorithm is presented in this study. Laminated piezoelectric patches serve as distributed sensors and actuators. Dynamic behaviors and mode shape functions in three directions are obtained by the Rayleith-Ritz method. The sensing sensitivity of the piezoelectric sensor and the actuation force of the piezoelectric actuator are obtained. Feedback control gain between sensing and control signals is solved using the LQ optimal control algorithm. LQ controllers for independent modes are designed, and relative optimal control gains and control voltages are presented. Control results with respect to independent mode and optimal design parameters are evaluated in case studies. Numerical results show that the LQ optimal controller with optimal feedback control gain is effective for the vibration control of parabolic cylindrical shell panels. The damping ratio can be greatly enhanced; the maximal damping ratio reach 7.79% for mode (1,3). Studies on parametric designs suggest that relatively larger Q22 and/or smaller R results in rapider reduction of mechanical motion with more control energy cost, and vice versa. These results would provide a design reference in practical engineering.
Linking 10 Years of Modular Design Research: Alternative Methods and Tool Chain Sequences to Support Product Platform Design
Authors: Otto Kevin , Hölttä-Otto Katja , Simpson Timothy W.
Published: February 2014

Modular product platforms have been shown to provide substantial cost and time savings while still allowing companies to offer a variety of products. As a result, a multitude of product platform methods have been developed over the last decade within the design research community. However, comparison and integration of suitable methods is difficult since the methods have, for the most part, been developed in isolation from one another. In reviewing the literature in modularity and product platforms, we create a generic set of twelve platform design activities. We then examine a set of product platform development processes used at several different companies, and from this form a generic sequence of the activities. We then associate the various developed methods to the sequence, thereby enabling the chaining together of the various modular and platform design methods developed by the community.
Wireless Charging of a Supercapacitor Model Vehicle Using Magnetic Resonance Coupling
Authors: Fu Minfan , Zhang Tong , Ma Chengbin , Zhu Xinen
Published: February 2014

This paper discusses the basic considerations and development of a prototype demo system for the wireless charging of supercapacitor electric vehicles, which uses magnetic resonance coupling. Considering future ubiquitous wireless vehicle stationary and dynamic charging facilities, supercapacitor could be an ideal device to store a reasonable amount of electrical energy for a relatively short period of time. The prototype system includes all the major functional components for an electric vehicle’s powertrain and wireless charging system including coils for energy emitting and receiving, a FPGA PWM input generation board, high frequency DC/AC inverter and AC/DC rectifier circuits, an on-board supercapacitor module, sensors for SOC level measurement and charging position detection, etc. All the components are integrated into a model electric vehicle. The prototype system well demonstrates the idea of the fast and frequent wireless charging of on-board supercapacitors. Promising results from initial experiments are explained; while further investigations, optimized design of components and a system-level optimization are needed.
On Chaotic Dynamics of a Double Pendulum Arm Excited by a Nonlinear Shaker Based RLC Circuit
Authors: Sado Danuta , Balthazar José M. , Felix Jorge L. P.
Published: February 2014

The chaotic dynamics of a double pendulum arm coupled to a nonlinear shaker based RLC circuit through a magnetic field is studied numerically. The nonlinear term, in the circuit, is introduced by considering that the voltage of the capacitor is a nonlinear function of the instantaneous electric charge. For the identification of the response of the system various techniques, including chaos techniques as bifurcation diagrams and time histories, power spectral densities (FFT), Poincaré maps and exponents of Lyapunov are used. This electromechanical system will represent a basic subsystem of any robot.
Parametric Resonance of a Self-Excited System Under External Force and Time Delay Influence
Authors: Warminski Jerzy , Warminska Anna
Published: February 2014

Vibrations of a nonlinear self-excited system driven by parametric excitation are presented in the paper. The considered model with one DOF includes a self-excitation term represented by a nonlinear Rayleigh function and also a periodically varied stiffness coefficient which represents parametric excitation. The influence of the external force or/and time delay, treated as a control signal, is demonstrated. Nonlinear parametric resonance is determined numerically and analytically by the multiple time scale method. The influence of time delay on the resonance zones and the frequency locking phenomenon is analysed.
A Study on Mixed Kinetic-Kinematic Equations for Multibody Systems
Authors: Kim Sung-Soo , Seo Bongcheol , Kim Myungho
Published: February 2014

In this paper, mixed kinetic-kinematic equations for a multibody system have been studied in order to resolve the difficulties of non-integrability of angular velocity vectors. As for the kinetic equations, the Newton-Euler equations of motion are considered. They are derived in terms of angular velocity and angular acceleration vectors expressed in the body fixed reference frames. As for the kinematic compatibility equations, two different equations are considered. One is from the relationship between the angular velocity vector and the time derivatives of Euler parameters. The other is from the relationship between the rotational orientation matrix, its time derivative, and the angular velocity vector. In order to investigate the accuracy of the solution methods using two different kinematic compatibility equations, simulations of a spherical pendulum model and a 1/6 robot vehicle model have been carried out. With different integration step-sizes, the constraint violation errors have been also investigated.
Four Motion Branches of an Origami Based Eight Bar Spatial Mechanism
Authors: Qin Yun , Dai Jian S.
Published: February 2014

An eight bar spatial mechanism inspired from an origami paper fold by considering the carton panels as links and creases as revolute joints is proposed. The constraint deposition and motion characteristics analyses of the eight bar spatial mechanism show that the mechanism implements one screw motion and one pure translation. The configuration space of the mechanism comprises four subspaces. Through adding different geometrical constraints to the eight bar spatial mechanism, different motions of the end-effector are limited leading to three 2-DOF and one 1-DOF motion branches. Additional geometrical constrained conditions in four motion branches with aimed motions of double translations, single translation and two single screw motions are revealed. In the first two motion branches, the eight bar spatial mechanism remains the constant relative orientations of joint-axes. However, the joint-axes of the eight bar spatial mechanism change their orientations in the last two motion branches. Kinematic analyses are discussed in four motion branches, respectively.
Computational and Experimental Analysis of Mechanical Systems With Revolute Clearance Joints
Authors: Cheriyan Sony , Flores Paulo , Lankarani Hamid M.
Published: February 2014

The main objective of this work is to present a computational and experimental study on the contact forces developed in revolute clearance joints. For this purpose, a well-known slider-crank mechanism with a revolute clearance joint between the connecting rod and slider is utilized. The intra-joint contact forces that generated at this clearance joints are computed by considered several different elastic and dissipative approaches, namely those based on the Hertz contact theory and the ESDU tribology-based for cylindrical contacts, along with a hysteresis-type dissipative damping. The normal contact force is augmented with the dry Coulomb’s friction force. An experimental apparatus is use to obtained some experimental data in order to verify and validate the computational models. From the outcomes reported in this paper, it is concluded that the selection of the appropriate contact force model with proper dissipative damping plays a significant role in the dynamic response of mechanical systems involving contact events at low or moderate impact velocities.
Temperature Influence on Nonlinear Responses of Timoshenko Beam
Authors: Warminska Anna , Warminski Jerzy , Manoach Emil
Published: February 2014

The goal of this paper is to study large amplitude vibrations of a Timoshenko beam under an influence of the elevated temperature. It is assumed that the beam gets the elevated temperature instantly and the temperature is uniformly distributed along the beam’s length and cross-section. The mathematical model represented by a set of partial differential equations is derived taking into account boundary conditions for a simply supported beam in the both ends. Next, the problem is reduced by the Galerkin method by means of free vibration modes. The influence of the temperature on a resonance localisation and nonlinear oscillations is studied numerically and analytically by the multiple time scale method.
An Investigation Into the Factors Influencing Student Capstone Project Selection
Authors: Harper Steven R. , Barrella Elise M. , Nagel Jacquelyn K. , Nagel Robert L.
Published: February 2014

Our engineering program includes a two-year capstone experience. At the beginning of this experience, students bid into projects by rank ordering first, second, and third choice projects. Students’ decisions for long term commitments, such as selecting a capstone team, use various forms of bounded rationality. When making a choice on which two year capstone project to select and rank, there may be many reasons why a particular student or set of students will pick a project. In this study, we looked across three years of project selection and ranking data using a competing hypothesis to gain insight into the reasons with the greatest explanatory power on why projects are chosen. Implication of what this means regarding the overall portfolio of projects is offered as well as how to craft projects and project descriptions such that they garner more student interest and can lead to more excitement and learning.
Building Fast to Think Faster: Exploiting Rapid Prototyping to Accelerate Ideation During Early Stage Design
Authors: Neeley W. Lawrence , Lim Kirsten , Zhu April , Yang Maria C.
Published: February 2014

While rapid prototyping has proved to be an invaluable resource for expediting particular phases of the design process, its decreasing cost of operation and increasing accessibility reveal greater potential for these tools to substantially impact the design process itself. While many studies have investigated the advantages of creating and interacting with physical models in engineering design, this study explores the value of delaying decisions and pursuing many prototypes as it applies to individual designers in the earliest phases of the design process. Inspired by The Second Toyota Paradox, we propose the use of Kolb’s theory of experiential learning to reconcile the implications of set-based rather than point-to-point engineering with the value of an individual designer’s learning through interactions with concrete objects. We compared the performance of engineering students in a design challenge. The independent variable was the number of prototypes the participant was required to produce in the first iteration. Participants who were instructed to produce more prototypes in the same amount of time in which their control counterparts were only required to produce one expressed much higher levels of time constraint and dissatisfaction in their primary prototypes. However, multiple-design participants’ prototypes performed better, showed significantly greater improvement between iterations; in addition, satisfaction increased significantly after completion of the final prototype. We look to Kolb’s theory of experiential learning and an individualized application of corporate concurrent engineering to suggest a new design process heavy in low-fidelity, low-quality physical models in early design stages.
Systems Simulation of Design for End-of-Life Recovery Under Uncertainty
Authors: Behdad Sara , Joseph Aaron T. , Thurston Deborah
Published: February 2014

Design for End of Life (DfEOL) recovery is a complex process that requires consideration of various design aspects including design for product life extension, design for reliability, design for disassembly, design for components reuse, and design for recyclability. There is a need for an analytical tool that helps designers integrate all these design aspects together and moreover investigate the impact of design features on the recovery network. The designer needs to predict the variability that design features bring into the reverse logistics network, including the variability in the amount, quality and timing of return flows and uncertainty in the remanufacturing operations such as disassembly time. In addition to the product design, the EOL recovery system performance is also affected by human decision making. The willingness of customers to keep used products in storage, the qualitative criteria used by remanufacturing companies to sort and categorize the returned used products and the manual disassembly operations influenced by the operator’s cognitive biases are examples of human decision making processes that impact product recovery. The nonlinear character of reverse logistics system along with the dynamic complexity as a result of uncertainties and cognitive biases are particularly troublesome. This paper establishes a simulation-based System Dynamics (SD) model of product life cycle to check interrelationship among product design features and their impacts on the amount, quality and timing of the return flows to the waste stream. The complex product take back process and recovery operations are modeled. Designers could use the results of the model to compare different design scenarios and to receive information about what design features bring problems or create opportunities for EOL recovery.
Rationale for a Modified Crutch Use Methodology for Individuals With Weak or Paralyzed Hip Abductor Muscles
Authors: Borrelli James , Haslach Henry W.
Published: February 2014

Individuals with weak or paralyzed hip abductors may make use of two methods to reduce pathological gait kinematics as a result of their disability; reducing the need for the hip abductors or developing an equivalent torque on the body. Compensatory motions such as torso tilting or hip hiking “balance” the body reducing the need for the torque that would be developed by the hip abductors. A contralateral crutch develops a body torque that is equivalent to that developed by the hip abductors. Individuals with weak or paralyzed hip abductors intuitively adopt a wide crutch stance, contrary to the prescribed method where the crutches are vertical in the frontal plane. Using a wide stance angle in the frontal plane is hypothesized to improve gait with weak or paralyzed hip abductors more so than when using crutches in the traditional manner. Crutches develop a torque on the body that is equivalent to what would be developed by the hip abductors while standing still. A wide stance angle increases the moment arm that the crutch force acts through while standing still, increasing the torque developed, potentially increasing the positive effect of the crutch which may reduce the need for compensatory motions. However, a similar effect has not been characterized during gait.

The hypothesis is that a wide crutch stance angle improves a gait with paralyzed hip abductors more so than a crutch used vertically in the frontal plane. The assumption is that this is accomplished by decreasing energy expenditure and/or reducing the need for compensatory motions more so than a crutch used vertically in the frontal plane. A three-dimensional dynamic model is used to test the hypothesis. The model predicts that excessive pelvis depression and decreased pelvic rotation result when the hip abductors are paralyzed. Compensatory motions, hip hiking and torso tilting, and crutch use are shown to decrease the prevalence of pathological kinematics. Crutch use with a wide stance angle improves gait kinematics more than a vertical crutch with the same body weight supported on it. This study provides evidence that the need for compensatory motions and the prevalence of pathological gait kinematics may be reduced when using a wide crutch stance angle compared to a vertical crutch stance angle.
Digital Representation of Physical Artifacts: The Effect of Low Cost, High Accuracy 3D Scanning Technologies on Engineering Education, Student Learning and Design Evaluation
Authors: Vasudevan Nitish , Tucker Conrad S.
Published: February 2014

This paper aims to address two fundamental challenges in engineering education; i) the disconnect between digital and tactile learning activities in traditional Engineering Design curricula and ii) variations in standards used to assess digital activities completed by students.

Digital 3D scanning technologies have the potential to mitigate the disconnect between digital and tactile learning activities by providing students with a real time understanding of the relationship between the digital and tactile design space in a real time, dynamic manner. In the process, students are introduced to the concept of reverse engineering as a means of understanding product assembly/disassembly as tactile activities, which can be then seamlessly represented/augmented in the digital space. The researchers of this work aim to understand the impact on the learning outcomes experienced by students when digital and tactile engineering activities are integrated in a real time dynamic manner.

To mitigate variations in standards used to assess digital activities completed by students, the authors propose employing a 3D similarity metric that quantifies the differences between digital solutions created by students and a baseline solution from which student solutions are compared against. By establishing a quantitative similarity metric to assess student solutions, variations in grading across different instructors can be minimized and scores finalized in a more timely and efficient manner.

The case study presented in this work is based on an Introduction to Engineering Design course, where freshmen students working both in individual and team based design projects are introduced to both digital and tactile activities. The research findings reveal students’ perception of 3D scanning technologies as it relates to their experiences with digital and tactile learning activities. After being introduced to digital and tactile activities, students’ performance are quantified through controlled design activities that are then assessed/graded using the proposed digital similarity metric.
A Framework for Modeling and Managing Mass Pedestrian Evacuations Involving Individuals With Disabilities: Networked Segways as Mobile Sensors and Actuators
Authors: Stuart Daniel , Christensen Keith , Chen Anthony , Cao Ke-Cai , Zeng Caibin , Chen YangQuan
Published: February 2014

Based on our previous work on Mobile Actuator and Sensor Network, Applied Fractional Calculus, Sensor Networks and BUMMPEE (Bottom-Up Modeling of Mass Pedestrian flows implications for the Effective Egress of individuals with disabilities), a general framework is proposed for modeling and managing Mass Pedestrian Evacuations (MPE) in this paper. A distinctive feature compared with previous work is the incorporation of Individuals with Disabilities (IwDs) in understanding modeling and control of mass pedestrians evacuations. Networked Segway Supported Responders (NSSR) have been firstly employed in the research of modeling and control/managing problem of crowd pedestrians as mobile sensors and mobile actuators. Future simulation and experimental results will be referenced for public policy professionals and planners for better evacuation policy making and route planning.
Inverse Characterization of Composite Materials Using Surrogate Models
Authors: Steuben John , Michopoulos John , Iliopoulos Athanasios , Turner Cameron
Published: February 2014

In recent years, methods for the inverse characterization of mechanical properties of materials have seen significant growth, mainly because of the availability of enabling technologies like full-field measurement techniques, inexpensive high performance computing resources, and automated testing. Unfortunately, as the complexity of the material system increases even the most advanced methods for inverse characterization produce results in compute times that are not practical for real time applications. To overcome this limitation we present a method that uses Non-Uniform Rational B-spline (NURBs) based surrogate modeling to generate a very efficient representation of the material model and the associated objective function. In addition, we present a method for identifying the global minimum of this objective function that corresponds to the elastic properties that characterize the material. Validation of this methodology is achieved through synthetic numerical experiments that include both isotropic and orthotropic specimens defined both analytically and numerically. Statistical analyses on the effects of experimental noise supplement these results. We conclude with remarks regarding the use of this technique to recover the elastic properties from materials tested utilizing multiaxial robotic systems.
Force and Hydraulic Displacement Amplification of Fiber Reinforced Soft Actuators
Authors: Bishop-Moser Joshua , Krishnan Girish , Kota Sridhar
Published: February 2014

Soft robots allow for complex continuum motions and shapes that conform to their environment. Using a fiber-reinforced elastomeric enclosure (FREE) driven by fluid provides a high power density, soft continuum actuator. While the force generation for a small subset of this structure known as McKibben actuators has been studied extensively, the force and moments generated by a wider set of fiber reinforcements have not been previously investigated. Using virtual work and kinematics derived from fiber inextensibility and fluid incompressibility, the force and moments for the entire design space of FREEs has been determined analytically. Graphical representations have been created, providing easy tools for synthesis and analysis of force and moments in all possible FREEs. The hydraulic displacement amplification, or volumetric transduction, of output motion to fluid displacement has also been determined using kinematics; this transduction gives an indication of stiffness of the structure. Graphical representations have also been created, providing a designer with an intuitive understanding of the behavior all FREE topologies.
An Investigation Into the Effectiveness of an Algorithmic Approach to Teaching Functional Modeling
Authors: Nagel Robert L. , Bohm Matt R. , Linsey Julie S.
Published: February 2014

The consideration of function is prevalent across numerous domains as a technique allowing complex problems to be abstracted into a form more readily solvable. In engineering design, functional models tend to be of a more generalized nature describing what a system should do based on customer needs, target specifications, objectives, and constraints. While the value of function in engineering design seems to be generally recognized, it remains a difficult concept to teach to engineering design students. In this paper, a study on the effectiveness of an algorithmic approach for teaching function and functional model generation is presented. This paper is a follow-up on to the 2012 ASME IDETC paper, An Algorithmic Approach to Teaching Functionality. This algorithmic approach uses a series of grammar rules to assemble function chains which then can be aggregated into a complete functional model. In this paper, the results of a study using the algorithmic approach at Texas A&M in a graduate level design course are presented. The analysis of the results is discussed, and the preliminary evidence shows promise toward supporting our hypothesis that the algorithmic approach has a positive impact on student learning.
Direct and Adjoint Sensitivity Analysis of Multibody Systems Using Maggi’s Equations
Authors: Dopico Daniel , Zhu Yitao , Sandu Adrian , Sandu Corina
Published: February 2014

The importance of the sensitivity analysis of multibody systems for several applications is well known, concretely design optimization based on the dynamics of multibody systems usually requires the sensitivity analysis of the equations of motion. A broad range of methods for the dynamics of multibody systems include the state space formulations based on Maggis equations, nullspace methods or coordinate partitioning. Dynamic sensitivities, when needed, are often calculated by means of finite differences but, depending of the number of parameters involved, this procedure can be very demanding in terms of CPU time and the accuracy obtained can be very poor in many cases. In this paper, several ways to perform the sensitivity analysis are explored and analytical expressions for the direct and adjoint sensitivity analysis of multibody systems are presented, all of them based on Maggi’s formulations. Moreover, two different approaches to the adjoint sensitivity analysis of multibody systems are presented.

Although particularized to one formulation, the general expressions provided in the paper, are intended to be easily generalized and applied to any other formulation that can be expressed as an ODE-like system of equations, including penalty formulations.

Besides, to check the validity and correctness of the proposed equations, the solutions of all the methods proposed are compared: 1) between them, 2) with the third party code FATODE and 3) with the numerical solution using real and complex perturbations.

Finally, all the techniques proposed are applied to the dynamical optimization of a multibody system.
Numerical Solutions of Generalized Oscillator Equations
Authors: Xu Yufeng , Agrawal Om P.
Published: February 2014

Harmonic oscillators play a fundamental role in many areas of science and engineering, such as classical mechanics, electronics, quantum physics, and others. As a result, harmonic oscillators have been studied extensively. Classical harmonic oscillators are defined using integer order derivatives. In recent years, fractional derivatives have been used to model the behaviors of damped systems more accurately. In this paper, we use three operators called K-, A- and B-operators to define the equation of motion of an oscillator. In contrast to fractional integral and derivative operators which use fractional power kernels or their variations in their definitions, the K-, A- and B-operators allow the kernel to be arbitrary. In the case when the kernel is a power kernel, these operators reduce to fractional integral and derivative operators. Thus, they are more general than the fractional integral and derivative operators. Because of the general nature of the K-, A- and B-operators, the harmonic oscillators are called the generalized harmonic oscillators. The equations of motion of a generalized harmonic oscillator are obtained using a generalized Euler-Lagrange equation presented recently. In general, the resulting equations cannot be solved in closed form. A numerical scheme is presented to solve these equations. To verify the effectiveness of the numerical scheme, a problem is considered for which a closed form solution could be found. Numerical solution for the problem is compared with the analytical solution. It is demonstrated that the numerical scheme is convergent, and the order of convergence is 2. For a special kernel, this scheme reduces to a scheme presented recently in the literature.
Using Tolerance-Maps to Transfer Datum Plane From Design Tolerancing to Machining Tolerancing
Authors: Jiang Ke , Davidson Joseph K. , Shah Jami J. , Liu Jianhua
Published: February 2014

Datum transfer is usually carried out to satisfy requirements of fixture and operation in manufacturing process. Often such requirements are different than the functional requirements used when choosing tolerances during design. Reassignment and recalculation of tolerances are required to evaluate whether a machining scheme can reach the desired design specification. Since a planar feature are widely utilized in datum reference frame, this paper mainly focuses on the transfer of one datum plane to another parallel plane-segment with round or polygonal shape by using 3D Tolerance-Maps. Firstly, a parametric model about two parallel planar features is proposed to describe the geometric properties and spatial relationships between a design datum and a machining datum. Then, based on a variation analysis of plane-to-plane datum transfer, a more elaborate transformation is utilized to relate T-Maps (Patent No. 6963824) with M-Map. Next, several rigid mathematical inequalities are presented to describe the boundaries of primitive and transformed T-Maps for further accumulation and comparison. The largest possible machining tolerances are determined by fitting the M-Map inside the design T-Map. Analytical relations between the machining and design tolerances are extracted from cross-sections through both T-Maps. Lastly, an example is illustrated to show feasibility of the method.
Minimum Energy Cognitive Lighting Control: Stability Analysis and Experiments
Authors: Yin Chun , Stark Brandon , Chen YangQuan , Zhong Shou-ming
Published: February 2014

Energy is one of the most important foundations of the world. However, the demand for lighting consumes a significant amount of electricity. In order to save lighting electricity and reduce cost, one obvious way is to supplement artificial light with natural light. The mixing of artificial and natural lighting, known as hybrid lighting, can be used to indoors for all lighting needs. In order to maintain the overall illumination level at the rated value, the amount of artificial light needs to change according to the varying natural light. To meet the desired energy saving potential, a suitable means for minimizing energy usage throughout the day must be developed. Minimum energy point tracking (MEPT) algorithms can be utilized to tackle this minimization problem. In this paper, a minimum energy cognitive lighting control prototype is proposed, designed and developed. A simple PID control law is implemented to maintain an arbitrary level of illumination while a sliding mode based extremum seeking controller (SM-ESC) is employed to minimize energy usage in the lights. Furthermore, this paper presents the experiment results of our MEPT research and tracking control for light level. The experimental results can show the practicality and effectiveness of the proposed minimum cognitive energy lighting control scheme.
Model Reduction for Nonlinear Structural Systems Using Balanced Realization Theory
Authors: Ferri Al
Published: February 2014

The development of accurate and efficient numerical models for jointed structures is an important and challenging problem. Due to nonlinearities in the joints, notably dry friction, contact stiffness, and impact, joint models are often complicated and computer-intensive. To create practical models, engineers typically combine “lumped joint models” with reduced-order models for the structural members that they connect. However, the model reduction often distorts how the joint behaves and sometimes destroys important qualitative traits. Simple modal truncation is often inadequate to produce reduced-order models because nonlinearities within the joints such as impact and dry friction can depend critically on the high-frequency characteristics of the mating structural elements. This paper examines the issues surrounding the development of accurate, reduced-order models for nonlinear, jointed structures. The concept of “balanced realizations” from control theory are used to create reduced-order models that best capture the input-output characterization of the linear substructures with the smallest model order. The balanced-realizations are seen to produce very favorable results when compared with standard modal truncation techniques.
Equivalent Circuit Modeling of Vehicle Dynamics With Regenerative Shock Absorbers
Authors: Li Peng , Zuo Lei
Published: February 2014

Regenerative shock absorbers have potential to recover a large amount of kinetic energy from vehicle vibration otherwise dissipated in traditional oil shock absorbers and at the same time to improve the ride comfort and road handling performances. Linear, rotational and mechanical motion rectifier (MMR) based electromagnetic designs have been proposed. They all have different energy conversion mechanisms, mass inertia effects, and even some nonlinear structures which make the damping behavior more complex; therefore their influence to the whole vehicle dynamics will need to be carefully assessed. This paper will present an integrated equivalent circuit model of the vehicle with electromagnetic regenerative shock absorbers, and then evaluate the vehicle dynamics performance and energy harvesting potential with different design parameters and under variable road conditions. The performance of different mechanisms of electromagnetic regenerative shock absorbers and constant shock absorber will be compared. Design guidelines for rotational electromagnetic regenerative shock absorbers will be developed based on analysis and simulation results.
Intrinsic Localized Modes of Harmonic Oscillations in Pendulum-Arrays Subjected to Horizontal Excitation
Authors: Ikeda Takashi , Harata Yuji , Nishimura Keisuke
Published: February 2014

The behavior of intrinsic localized modes (ILMs) is investigated for an array with N pendula which are connected with each other by weak, linear springs when the array is subjected to horizontal, sinusoidal excitation. In the theoretical analysis, van der Pol’s method is employed to determine the expressions for the frequency response curves for fundamental harmonic oscillations. In the numerical calculations, the frequency response curves are presented for N = 2 and 3 and compared with the results of the numerical simulations. Patterns of oscillations are classified according to the stable steady-state solutions of the response curves, and the patterns in which ILMs appear are discussed in detail. The influence of the connecting springs of the pendula on the appearance of ILMs is examined. Increasing the values of the connecting spring constants may affect the excitation frequency range of ILMs and cause Hopf bifurcation to occur, followed by amplitude modulated motions (AMMs) including chaotic vibrations. The influence of the imperfections of the pendula on the system response is also investigated. Bifurcation sets are calculated to examine the influence of the system parameters on the excitation frequency range of ILMs and determine the threshold value for the connecting spring constant after which ILMs do not appear. Experiments were conducted for N = 2, and the data were compared with the theoretical results in order to confirm the validity of the theoretical analysis.
Condition Monitoring of Marine Couplings by Means of Vibration Analysis Techniques
Authors: Delvecchio Simone , D’Elia Gianluca , Dalpiaz Giorgio
Published: February 2014

This paper shows the application of some processing techniques for the vibration analysis in working conditions of two different types of marine flexible couplings for boat propulsion. The flexible couplings are mounted between the flywheel of the marine diesel engine and the propeller shaft. The vibration signals are processed in time and frequency domain. Moreover, due to the presence of impulses in the signals, Continuous (CWT) and Discrete Wavelet Transform (DWT) are applied and compared with the conventional time and frequency domain methods. In this work the wavelet analysis is used for the impulse component extraction and the choice of different wavelet functions for this purpose is evaluated. The experimental comparison between two different types of couplings is also given. The results suggest that the wavelet transform techniques are effective to indicate which type of coupling provides a good vibrational behaviour especially in working condition when the angular speed of the propeller shaft is often inverted.
Multi-Objective Optimization of a Disc Brake System by Using SPEA2 and RBFN
Authors: Amouzgar Kaveh , Rashid Asim , Stromberg Niclas
Published: February 2014

Many engineering design optimization problems involve multiple conflicting objectives, which today often are obtained by computational expensive finite element simulations. Evolutionary multi-objective optimization (EMO) methods based on surrogate modeling is one approach of solving this class of problems. In this paper, multi-objective optimization of a disc brake system to a heavy truck by using EMO and radial basis function networks (RBFN) is presented. Three conflicting objectives are considered. These are: 1) minimizing the maximum temperature of the disc brake, 2) maximizing the brake energy of the system and 3) minimizing the mass of the back plate of the brake pad. An iterative Latin hypercube sampling method is used to construct the design of experiments (DoE) for the design variables. Next, thermo-mechanical finite element analysis of the disc brake, including frictional heating between the pad and the disc, is performed in order to determine the values of the first two objectives for the DoE. Surrogate models for the maximum temperature and the brake energy are created using RBFN with polynomial biases. Different radial basis functions are compared using statistical errors and cross validation errors (PRESS) to evaluate the accuracy of the surrogate models and to select the most accurate radial basis function. The multi-objective optimization problem is then solved by employing EMO using the strength Pareto evolutionary algorithm (SPEA2). Finally, the Pareto fronts generated by the proposed methodology are presented and discussed.
Anti-Control of Chaos in Fractional Difference Equations
Authors: Li Changpin , Ma Li , Xiao Huang
Published: February 2014

Fractional difference equations, or fractional maps, appear at least in two ways. One way is that some of them directly come from the discrete dynamical process with memory or heredity. Another one is that some of them are originated from the discretization of the continuous fractional differential equations. Such maps may be not chaotic. On the other hand, anti-control of chaos (or chaotification for brevity) has potential applications in secure communication. In this paper, we make non-chaotic fractional maps chaotic by constructing suitable controllers. The presented control technique and method has been applied to the non-chaotic fractional Tent map, Hénon map, and Lozi map, which become chaotic via the designed controllers. The computer graphics are also displayed to show the efficiency of the designed controllers.
Curvature Analysis and Hertzian Contact Stress of a Modified Curvilinear Gear Set With Localized Bearing Contact
Authors: Chen Yi-Cheng , Lo Chien-Cheng , Chen Wei-Cheng
Published: February 2014

This paper investigates the contact ellipse and contact stress of a modified curvilinear gear set with localized bearing contact. The proposed modified curvilinear gear set with profile modifications was generated by male fly cutters with a circular-arc normal section. This gear drive exhibits point contact and parabolic transmission error under an ideal meshing condition according to the results of tooth contact analysis. The principal directions and curvatures of the mating pinion and gear surfaces were derived from those of the generating surfaces on the basis of differential geometry and theory of gearing. The Hertzian contact stress and contact ellipses of the mating tooth surfaces were determined with our developed computer program based on formulae of curvature analysis and Hertzian contact theory. Numerical examples were also provided to demonstrate the computational results.
Option-Based Risk Management Method of Challenging Design Project
Authors: Nomaguchi Yutaka , Horinouchi Takahiro , Dong Chunzhi , Fujita Kikuo
Published: February 2014

This paper proposes an adaptive method of planning design project to handle uncertainty with a task option model. The model considers a task option to perform a challenging design or change it to a conservative one which is a backup of it in order to accommodate various risks. A planning problem is formulated under the assumption that a design project and its process consist of multiple task options, each of which corresponds to a component of the product. A project manager decides the switches of the task by checking the design progress at the milestones. A growth curve model of design progress is adopted to predict the design progress for risk assessment. This research also demonstrates a planning example of a student formula car project and discusses the application of the proposed method.
Aeroelastic Tailoring of Helicopter Blades
Authors: Cornette Donatien , Kerdreux Benjamin , Gourinat Yves , Michon Guilhem
Published: February 2014

The dynamic loads transmitted from the rotor to the airframe are responsible for vibrations, discomfort and alternate stress of components. A new and promising way to minimize vibration is to reduce dynamic loads at their source by performing an aeroelastic optimization of the rotor.

This optimization is done thanks to couplings between the flapwise-bending motion and the torsion motion. The impact of elastic couplings (composite anisotropy) on the blade dynamic behaviour and on dynamic loads are evaluated in this paper.

Firstly, analytical results, based on a purely linear modal approach, are given to understand the influence of those couplings in terms of frequency placement, aerodynamic lift load and vertical shear modification. Then, those elastic couplings are introduced on a simplified but representative blade (homogeneous beam with constant chord) and results are presented.
Torque Vectoring Control of a Four Independent Wheel Drive Electric Vehicle
Authors: Cheli Federico , Melzi Stefano , Sabbioni Edoardo , Vignati Michele
Published: February 2014

In recent years the interest towards electric vehicles has increased. Among the different layout of the electric powertrain, four in-wheel motors appear to be one of the most attractive. This configuration in fact allows to re-design inner spaces of the vehicle and presents, as an embedded feature, the possibility of independently distributed braking and driving torques on the wheels in order to generate a yaw moment able to improve vehicle handling (torque vectoring). The present paper presents and compares two different torque vectoring control strategies for an electric vehicle with four in-wheel motors. Performances of the control strategies are evaluated by means of numerical simulations of open and closed loop maneuvers, also taking into account their energetic efficiency.
Effects of Helix Angle on Root Stresses of Thin-Rimmed Helical Gears With Various Web Arrangements
Authors: Miyachika Kouitsu , Nafiz Bin Daing Idris Daing Mohamad
Published: February 2014

Root stresses of thin-rimmed helical gears with symmetric and asymmetric web arrangement of helix angle β0 = 10° and 20°, which were meshed with solid helical gear, were measured from the beginning of engagement to the end of the engagement by using the strain gauge method. The changes of root stresses from the beginning of engagement to the end of engagement were examined. The effects of helix angle, rim thickness, web thickness and web structure on the root stresses, the maximum root stress and the meshing position, where the maximum root stress (worst loading position) occurs, were clarified. Furthermore, the obtained results were compared with the results of the solid helical gear. On the basis of these results, the maximum root stress of thin-rimmed helical gears with helix angle β0 = 10° occurs at the outer point of single tooth contact, and at the position of a transverse base pitch distant from the tip toward the root along the line of action for β0 = 20°. For thin-rimmed helical gears with the same rim thickness, web thickness and web structure, maximum root stress increment ratio (maximum root stress of thin-rimmed helical gear divided by maximum root stress of solid helical gear) of thin-rimmed helical gears with helix angle β0 = 10° are larger compared to the case of β0 = 20°.
Style Design System Based on High-Quality Aesthetic Shapes to Support Designer’s Creative Activity
Authors: Kimura Fumihiko , Oya Tetsuo , Aoyama Hideki
Published: February 2014

Class A shapes are used as an aesthetic standard mainly in automotive industry. Those used in products’ exterior are closely related to products’ values. Class A shapes have two geometric conditions: The surface has enough geometrical continuity, and smooth and continuous highlight lines. In our previous study, we developed a Class A curve generating method and style design system. Using this system, an user can create a model with several Class A curves. Then, we created a model by this system to evaluate the proposed method. Although we can create an aesthetic shape using this system, some shapes were not good in curvature variation. There is reason why some generated curves didn’t produce Class A shapes. In this study, we investigate more detailed conditions of Class A curve, and improve the Class A shape generating method using Class A curve. In our new method, we extend the range of Class A conditions. By this extension, Class A shape can be generated more efficiently than the previous method. Then, we create a model using this method in order to evaluate the surface quality, and discuss the effectiveness of our system.
Building of Usage Scenarios Space for Investigating the Fall Situations of the Elderly People
Authors: Bekhradi Alborz , Yannou Bernard , Farel Romain , Zimmer Benjamin
Published: February 2014

Assessing the number of users defined by a set of specific usage attributes in a given usage contextual situation is not always an obvious task in a market segmentation process. Although new approaches in design and marketing seem to be more sensitive to the adequacy of a design concept with the usage scenarios, these methods do not systematically consider the various usage situations. The present article puts forward a methodology intending to build a usage scenarios space in which the input data is thoroughly collected and validated. This methodology is applied to the complex and multifactorial issue of falls among the elderly in the Metropolitan France. In this paper, numerous medical publications have been made to study influential factors of fall situations. However, even solution providers for fall prevention and teleassistance ignore the real situational coverage of their solutions. As a result, “usage scenarios space” is built using an appropriate segmentation of usage contexts (here, fall situations) and user characteristics. These data are used for a design oracle to predict (simulate) the various and multiple usage scenarios.