bluuebunny/crossref_metadata_2025 huggingface dataset:
What Is the Optimal Shape of a Snap Ring?
Authors: Stro¨mberg Niclas
Published: May 2009

In this paper a non-linear elastic ring is studied by using a method for contact/impact problems. The method is developed for frictional contact, impact and rolling between a two-dimensional hyperelastic body and rigid foundations. The elastic properties of the body are defined by coupling the second Piola-Kirchhoff stress to the Green-Lagrange strain via the Kirchhoff-St. Venant law. The rigid supports are described by smooth functions. By introducing the mean value impulses, these functions are utilized to formulate new contact/impact laws. The support functions appear explicitly in the variational formulation of Signorini, and implicitly in the maximal dissipation principle of Coulomb. A feature of this approach is that no search algorithm is needed. Another feature is that the normal and tangential directions of the supports are well defined. The above constitutive assumptions together with the law of motion, which is written on velocity form, define the governing equations of the system. These are solved by a nonsmooth Newton method. The method is utilized to study the contact pressure between a snap ring and a rigid groove which has the shape of a perfect circle. It is obvious that if the snap ring also has the shape of a perfect circle, then the distribution of the contact pressure will be uneven. An even distribution of the contact pressure is preferable in order to improve function and increase lifetime. The question that is considered in this paper is how the shape of the ring should be designed in order to produce this type of contact pressure.
Integration Method of CAD Systems
Authors: Vlasenko Dmitry , Kasper Roland
Published: May 2009

This paper presents the modification of a non-iterative algorithm for the component-oriented simulation of the dynamics of multibodies. Now the method can be implemented for the component-oriented simulation of the dynamics of CAD systems with redundant constraints. Also the new version of the method is well-suitable for the implementation of sparse solvers. The algorithm was implemented in the Virtual System Designer (VSD) software, integrated with a CAD tool Autodesk Inventor. The simulation results of two CAD models: a car and a steam machine shows the method’s stability and accuracy.
On the Design of PAMINSA: A New Class of Parallel Manipulators With High-Load Carrying Capacity
Authors: Briot Se´bastien , Gue´gan Sylvain , Courteille Eric , Arakelian Vigen
Published: May 2009

This paper deals with the new results concerning the topologically decoupled parallel manipulators called PAMINSA. The conceptual design of these manipulators, in which the copying properties of pantograph linkage are used, allows obtaining a large payload capability. A newly synthesized fully decoupled 3 degrees of freedom manipulator is discussed and a systematic approach for motion generation of input point of each limb is presented. It is shown that the conditions of complete static balancing of limbs are not effective in the case of dynamic mode of operation. This is approved by numerical simulations and experiments. A significant contribution of this paper is also the experimental validation of the suggested design concept. It is shown experimentally for the first time that the static loads on the rotating actuators, which displace the platform in the horizontal plane, are cancelled.
Theoretical and Experimental Investigation of Optical Excitation of Nano Oscillators
Authors: Krylov Slava , Ilic Bojan , Kondratovich Marianna , Craighead Harold G.
Published: May 2009

In the present work we report on theoretical and experimental investigation of optical resonant excitation of nano cantilevers fabricated from silicon nitride and mono-crystalline silicon layers deposited on top of a sacrificial silicon dioxide layer. The thermal energy impinged into the structure was produced by a laser beam focused at the substrate and not at the structure itself. Steady-periodic axisymmetric thermal problem for a multilayered structure heated with a modulated laser was treated analytically using an integral transform technique and verified by finite element analysis which was implemented also for the solution of steady-periodic and transient thermoelastic problems. A transfer function relating the laser source parameters to the NEMS structure response was constructed and influence of various parameters on the nanoelectromechanical structure NEMS response was investigated. Results of analysis backed by experiments indicate that the dominant actuation mechanism in the case of laser spot located in proximity of the structure was primarily thermal.
Simulation-Based and Experimental Studies of Subjective Clustering and Bootstrap Application to Subjective Clustering
Authors: Lakshminarayana Ramaprasad E. , Bhardwaj Nishant , Takai Shun
Published: May 2009

The success of any product in today’s competitive market is dictated by its ability to satisfy the needs of the customers. In this effort, it is important to group similar needs to recognize representative needs, and then identify product requirements that can fulfill these representative needs. One approach to this is to apply Subjective Clustering (SC) to sample data (grouping of customer needs by a sample of customers); however, clusters obtained by SC give only a point estimate of the primary clusters of customer needs by the entire population of customers (population primary clusters). Applying Bootstrap to SC (BS-SC) helps engineers to make inferences on the population primary clusters. In this paper, we randomly pulled out samples of different sizes from both the simulation approach using simulation-generated population data and the empirical approach using experimental population data, and compared the accuracies of SC and BS-SC. Regardless of population sizes, when the sample size was small, BS-SC was more accurate than SC in estimating the population primary clusters. Also, the BS-SC and SC estimates were similar for both simulation and empirical approaches.
A Novel Fuzzy Controller to Improve Desired Suspension Performance
Authors: Biglarbegian Mohammad , Melek William , Golnaraghi Farid
Published: May 2009

Semi-active suspension systems allow for adjusting the vehicle shock damping and hence improved suspension performance can be achieved over passive methods. This paper presents the design of a novel fuzzy control structure to concurrently improve ride comfort and road handling of vehicles with semi-active suspension system. A full car model with seven degrees of freedom is adopted that includes the vertical, roll, and pitch motions as well as the vertical motions of each wheel. Four decentralized fuzzy controllers are developed and applied to each individual damper in the vehicle suspension system. Mamdani’s method is applied to infer the damping coefficient output from the fuzzy controller. To evaluate the performance of the proposed controller, numerical analyses were carried out on a real road bump. Moreover, results were compared with well-known and widely used controllers such as Skyhook. It is shown that the proposed fuzzy controller is capable of achieving enhanced ride comfort and road handling over other widely used control methods.
Effect of Feedback Delays on Nonlinear Vibrations of Cantilever Beams
Authors: Daqaq Mohammed F. , Alhazza Khaled A. , Stanton Samuel
Published: May 2009

The authors present a comprehensive investigation of the effect of feedback delays on the nonlinear vibrations of piezoelectrically-actuated cantilever beams. More specifically, in the first part of this work, we examine the free response of a cantilever beam subjected to delayed-acceleration feedback. We characterize the stability of the trivial solutions and determine the normal form of the bifurcation at the stability boundary. We show that the trivial solutions lose stability via a Hopf bifurcation leading to limit-cycle oscillations (LCO). We assess the stability of the resulting LCO close to the stability boundary by determining the nature of the Hopf bifurcation (sub-or supercritical). We show that the bifurcation type depends only on the frequency of the delayed-response at the bifurcation point and the coefficients of the beam geometric and inertia nonlinearities. To analyze the stability of the LCO in the postbifurcation region, we utilize the Method of Harmonic Balance and the Floquet Theory. We observe that, increasing the gain magnitude for certain feedback delays may culminate in a chaotic response. In the second part of this study, we analyze the effect of feedback delays on a cantilever beam subjected to primary base excitations. We find that the nature of the forced response is largely determined by the stability of the trivial solutions of the unforced response. For stable trivial solutions (i.e., inside the stability boundaries of the linear system), the free response emanating from delayed feedback diminishes leaving only the particular solution resulting from the external excitation. In that case, delayed feedback acts as a vibration absorber. On the other hand, for unstable trivial solutions, the response contains two coexisting frequencies. Therefore, depending on the excitation amplitude and the closeness of the frequency of the delayed response to the excitation frequency, the response is either periodic or quasiperiodic. Finally, we study the effect of higher vibration modes on the beam response. We show that the validity of a single-mode analysis is dependent on the gain-delay combination utilized for feedback as well as the position and size of the piezoelectric patch.
On Non-Linear and Non-Ideal Interactions in Two Vibrating Problems
Authors: Pala´cios Felix J. L. , Balthazar J. M. , Brasil R. M. L. R. F. , Krasnopolskaya T. S. , Shevets A. Y.
Published: May 2009

In practical situations, the dynamics of the forcing function on a vibrating system cannot be considered as given a priori, and it must be taken as a consequence of the dynamics of the whole system. In other words, the forcing source has limited power, as that provided by a DC motor for an example, and thus its own dynamics is influenced by that of the vibrating system being forced. This increases the number of degrees of freedom of the problem, and it is called a non-ideal problem. In this work, we considerer two non-ideal problems analyzed by using numerical simulations. The existence of the Sommerfeld effect was verified, that is, the effect of getting stuck at resonance (energy imparted to the DC motor being used to excite large amplitude motions of the supporting structure). We considered two kinds of non-ideal problem: one related to the transverse vibrations of a shaft carrying two disks and another to a piezoceramic bar transducer powered by a vacuum tube generated by a non-ideal source.
Feedback Delays for Ultrasensitive Sensing
Authors: Daqaq Mohammed F. , Bradley Calvin , Jalili Nader , Alhazza Khaled
Published: May 2009

Nanomechanical Cantilever Sensors (NMCS) have recently emerged as an effective means for label-free chemical and biological species detection. Their high selectivity, low cost, and easy mass production make them an enabling technology for micro- and nanodetection techniques. Sensitivity constitutes one of the most desirable characteristics of NMCS. However, sensitivity of current NMCS is predominately limited by their size. In other words, smaller sensors are more sensitive than larger ones. The detection of ultra-small masses or frequency variations is therefore obstructed by the availability of more advanced fabrication techniques that are capable of manufacturing smaller and smaller sensors. Even in that case, other issues such as noise, damping, and measurement difficulties become more evident. Therefore, techniques for sensitivity enhancement should be studied and implemented to allow for accurate and precise detection of even smaller parameter variations. Along that line of reasoning, we propose a simple, but effective concept to enhance sensitivity of NMCS. The proposed methodology is based on utilizing feedback delays to create a limit-cycle response whose amplitude is ultra-sensitive to frequency variations. In this paper, we explain, analyze, and derive the equations that verify the proposed concept. We then experimentally implement the sensitivity enhancement technique on a macrocantilever beam and demonstrate more than two-orders-of-magnitude sensitivity enhancement over the frequency-shift method.
Detection of Carrier-Plate Cracks Using Vibration Spectra
Authors: Patrick Romano , Ferri Al , Vachtsevanos George
Published: May 2009

This paper examines the problem of identifying cracks in planetary gear systems through use of vibration sensors on the stationary gearbox housing. In particular, the effect of unequal spacing of planet gears relative to the rotating carrier plate on various frequency components in the vibration spectra is studied. The mathematical analysis is validated with experimental data comparing the vibration signature of helicopter transmissions operating either normally or with damage leading to shifts in the planet gear positions. The theory presented is able to explain certain features and trends in the measured vibration signals of healthy and faulty transmissions. The characterization offered may serve as a means of detecting damage in planetary gear systems.
Vibration Analysis of Cable-Driven Parallel Manipulators for Hardware-in-the-Loop Contact-Dynamics Simulation
Authors: Diao Xiumin , Ma Ou
Published: May 2009

Possible vibration of cable-driven parallel manipulators (called cable manipulators for short) is a concern for some special applications such as hardware-in-the-loop (HIL) contact-dynamics simulation of spacecraft or space robotic systems. A cable manipulator used in HIL simulation is required to be rigid enough to have a high bandwidth to respond its input. This paper provides a vibration analysis of a general 6-DOF cable manipulator. Under an excitation, a cable may deflect in both axial and lateral directions due to its inevitable flexibility. The vibrations of cable manipulators caused by cable flexibility in both axial and lateral directions are analyzed. The study demonstrated that the cable manipulator can provide sufficient rigidity for applications like HIL contact-dynamics simulation of a spacecraft or space robotic system. It is also shown that the vibration of a cable manipulator due to the lateral flexibility of cables can be ignored comparing to that due to the axial flexibility of cables.
Three Dimensional Vibration Measurements Using a Five-Axis Scanning Laser Vibrometry System
Authors: O’Malley Patrick F. , Judge John A. , Vignola Joseph F.
Published: May 2009

This paper describes an experimental facility designed to measure three-dimensional velocity components using a five-axis laser vibrometry system. A single-point laser Doppler vibrometer (LDV) is mounted on three orthogonal translation stages, and the beam is directed to the target specimen by means of a mirror mounted at the intersection of the axes of two rotational stages. The result is a system with which the vibration of points on the surface of the test specimen can be measured from multiple angles, and these multiple measured components of the surface velocity are combined to determine the full velocity vector in three-dimensions. This system allows collection of a richer data set for more detailed vibration analysis, measurement of vibration of non-planar surfaces, and greater control over measurements compared to conventional single-beam scanning LDV, while greatly reducing experimental facility costs compared with threedimensional LDV systems that use multiple lasers.
An Experimental Analysis of the Dynamics of Lightly Damped Subcritically Excited Gear Pairs
Authors: Ottewill James R. , Wilson R. Eddie , Neild Simon A.
Published: May 2009

This paper investigates, through experimentation, the inherently nonlinear dynamics that meshing gear pairs display. The experimental rig consists of 1:1 ratio high-module spur gears connected to high precision encoders. The amplitude of a displacement fluctuation input is varied and the relative motion of the two gears is recorded. The experimental trajectories show at least two stable impacting regimes for each fluctuating input amplitude, differing in the magnitude of the relative angular displacement. The amplitude of motions is sometimes comparable to the backlash size, and for some parameters both noisy solutions with large relative displacement amplitudes and quieter, smaller amplitude solutions may occur. A simple single degree of freedom model is derived, based upon a combined constant velocity and fluctuating displacement input. This model is compared with experimental results in order to understand fundamental contact mechanics. Solutions to the mathematical model are generated using a numerical integrator and predict the maximum relative displacement amplitude motions accurately, but not the smaller amplitude motions. This is because the model omits and simplifies certain mechanisms such as meshing impacts and gear eccentricity, both of which will be added in future investigation.
An Efficient Modeling of Flexible Blimps: Eulerian Approach
Authors: Bennaceur Selima , Azouz Naoufel , Abichou Azgal
Published: May 2009

Unmanned Aerial Vehicles (U.A.V.) have a need of a greater autonomy in their new missions. Autonomous U.A.V. flight control systems require a precise modeling of the dynamic behavior taking into account the effect of the flexibility and the interaction with the surrounding fluid. In this paper, we present an efficient modeling of the autonomous flexible blimps. These flying objects are assumed to undergo large rigid-body motion and small elastic deformations. The formalism used is based on the Newton-Euler approach. This one is frequently used for flying rigid objects. In this study we develop a method to generalize the existing Newton-Euler “rigid body” formalisms by including the effect of the flexibility without destroying the global methodology. The method is hybrid. It uses the Lagrange equations and the Eulerian variables. The flexibility appears in the global dynamical system by the way of few supplementary degrees of freedom. This method has the advantage of making easier the elaboration of algorithms of control, stabilization or generation of trajectories. The added mass phenomenon is also taken into account in the dynamical system. This phenomenon is important for big and light objects moving in a fluid such as airships. As validation we use the parameters of an AS-200 blimp belonging to the University of Evry.
On the Investigation of Machine Tool Chatter in the Milling Process
Authors: Moghaddas Mahsa , Ghaffari Saadat Mohammad H.
Published: May 2009

In this paper, the chatter phenomenon is investigated through a single degree of freedom model of the milling process. In this regard, the non-linear equation of motion obtained from modeling of the milling process, which is a time-periodic delay differential equation, is simulated, and by changing the parameters: spindle speed and depth of cut, and assuming constant quantities for other parameters of the system the stable and instable points for the system are gained according to these two parameters by numerical method. In the end, the stability chart for this system is plotted and the approximate boundaries between the stability and instability regions are obtained numerically.
Rocking and Slip Coupled Seismic Response of Large and Flexible Cylindrical Storage Tanks
Authors: Kobayashi Nobuyuki , Seo Noriaki , Watanabe Masahiro , Pfeiffer Friedrich
Published: May 2009

The slip and rocking coupled response of the unanchored flexible cylindrical storage tanks due to the seismic excitation is investigated. A five-degrees of freedom mechanical model is developed in order to examine the slip and rocking coupled seismic response accompanied with the uplifting of the base plate. The model takes into account the flexibility of the tank shell and bottom plate, the hydrodynamic pressure effect of the contained liquid to the tank shell and bottom plate as well as the slip and rocking motion introducing the unilateral contact. The validity of the presented mechanical model is demonstrated by the shaking table experiments with a scale model tank. As the numerical simulations results, it is clarified that slip and rocking coupled motion gives significant effect on the seismic response of the tank, and the taller tank is easier to slip than the broader ones is.
Design and Development of a Low-Cost Wireless Data Glove for Remote Robotic Hand Operation
Authors: Labutov Igor
Published: May 2009

The goal of this project is to develop a teleoperated robotic hand with an emphasis on minimizing cost. Traditionally, use of low-cost sensors meant a sacrifice in the positional accuracy of the finger joints due to noise and high degree of nonlinearity. External vision systems provide accurate data, but suffer from being limited to specific lighting conditions and are hardly mobile. We have developed a robust data glove with a wireless connectivity to a nearby PC that is networked to a robotic arm in the different laboratory through a wireless LAN. In its prototype stage, each finger is modeled as a single joint. To measure the relative angular displacement of each joint, a hollow transparent polyurethane tube is attached along the length of each finger. An Infrared LED and a matched phototransistor are attached at the opposite ends of each tube. The bending of each finger proportionally diminishes the intensity of the light seen by the phototransistor, as a fraction of emitted energy escapes through the bend of the transparent tube. To filter the affects of external lighting and mains coupling each IR source is modulated at different frequencies to prevent interference between the signals. The relationship between relative angular displacement and the sensor signal is a highly nonlinear function that we have linearized through a combination of a non-linear amplifier and a digital look-up-table (LUT). The LUT is generated by custom-designed computer vision software that fits the true angular displacements to the function generated by passing the signal through a non-linear amplifier stage. A low-cost onboard 8-bit microcontroller applies the stored LUT to the digitized measurements from the sensors. The 16-bit positional values are then transmitted by a UDP (Universal Data Protocol) to the client PC that outputs motor commands to the servos in the robotic hand. Positional accuracy, noise and linearity were then analyzed by the same machine vision software and its effectiveness compared to the pure machine vision approach.
Nonlinear Resonator With Interacting Flexural-Torsional Modes for Mass Sensing
Authors: Vyas Ashwin , Bajaj Anil K. , Peroulis Dimitrios
Published: May 2009

We explore the use of a pedal shaped nonlinear microresonator designed with torsion and flexural modes in 1:2 internal resonance for mass sensing. The higher natural frequency in-plane flexural mode of the resonator is coupled nonlinearly through inertial coupling to the out-of-plane torsional mode with one-half natural frequency. When the flexural mode excited resonantly has response above a threshold, the torsional mode is excited. This response in torsional mode is highly sensitive to any mass perturbation that results in mistuning the two modes away from 1:2 resonance. The mistuning can drastically change the nonlinearly excited torsional response from non-zero amplitude to zero amplitude. The required increase in the actuation strength to reactivate the torsional motion can serve as a measure for the attached mass.
Representation of Similarity and Dependency for Manufacturing Process-Based Product Modularity
Authors: Lai Xiaoxia , Gershenson John K.
Published: May 2009

Previously in this forum, we validated a product modularity measure and modular product design method and developed a way to extend these product modularity fundamentals to encompass the impacts of assembly process similarity and dependency. This paper expands the life-cycle process-based modularity representation to the manufacturing process and beyond. Modularity representation, including similarity and dependency, is an important aspect of modular product design and it is imperative for realizing the promised cost savings of modularity. The component-component similarity matrix is used to cluster components with similar manufacturing processes into one module. Similarities are based on component processing codes that represent their manufacturing attributes. Clustering these manufacturing process similarities leads to cost savings through module-wide sharing of process plans, manufacturing tools, and equipment, and the reduction of manufacturing tool and equipment changes during manufacturing. The component-component dependency matrix is based on physical interactions among the components that affect the material, shape, size, surface finish etc. of the components, and therefore affect the component manufacturing processes. If components are independent of other components not in the same module with respect to these physical interactions, the redesign of components in one module will not cause a cascade of design and manufacturing process plan changes for components not in the same module. A fishing reel example is used to illustrate the application of manufacturing process similarity and dependency representations, in association with a product modularity measure and a modular product design method, to form manufacturing process-based component modules. The work in this paper establishes how to represent manufacturing process similarity and dependency for use in product modularity decision making. The use of such modules improves the efficiency of manufacturing process planning, and reduces design and manufacturing process costs.
Design and Implementation of an Efficient Multibody Divide and Conquer Algorithm
Authors: Critchley James H. , Binani Adarsh , Anderson Kurt
Published: May 2009

A new and efficient form of Featherstone’s multibody Divide and Conquer Algorithm (DCA) is presented. The DCA was the first algorithm to achieve theoretically optimal logarithmic time complexity with a theoretical minimum of parallel computer resources for general problems of multibody dynamics, however the DCA is extremely inefficient in the presence of small to modest parallel computers. This alternative efficient DCA approach (DCAe) demonstrates that large DCA subsystems can be constructed using fast sequential techniques to realize a substantial increase in speed. The usefullness of the DCAe is directly demonstrated in an application to a four processor workstation and compared with results from the original DCA and a fast sequential recursive method. Previously the DCA was a tool intended for a future generation of parallel computers, this enhanced version delivers practical and competitive performance with the parallel computers of today.
Numerical Simulation of Supersonic MHD Channel Flows
Authors: Amano R. S. , Xu Zhenyu , Lee Chun-Hian
Published: May 2009

A compressible magneto hydrodynamic (MHD) model composed of MHD Navier-Stokes (N-S) equations and magnetic induction equations is proposed in the present study for analyzing the magneto hydrodynamic characteristics in the MHD generator and MHD accelerator channels of the Magneto-Plasma-Chemical propulsion system. Baldwin-Lomax turbulence model is utilized. A splitting algorithm based on an alternative iteration is also developed for solving the two sets of equations. As a test case, a supersonic MHD flow in a square duct was simulated. The numerical results are compared with the results computed by solving the classical N-S equations for the perfect gas flow, together with the results computed utilizing the degenerate MHD N-S equations for the same channel flow with constant applied magnetic field. The thermo-electro-magnetic performances of the test cases with constant and variable applied fields are then discussed.
Quantity Dimension Indexing for Design Knowledge Management
Authors: Murakami Tamotsu , Suehisa Yasushi
Published: May 2009

Although many knowledge management techniques based on text expression have been developed, they are not necessarily sufficient for managing engineering design knowledge. In this paper, we propose quantity dimension indexing of design knowledge as a fundamental method for design knowledge management. Physical quantities describing physical phenomena can be represented as vectors in a seven-dimensional space where the orthogonal axes are the seven base units of the SI (The International System of Units). Because of the generality, objectivity and universality of the SI, this space covers all physical quantities that appear in the past, present and future design knowledge and design problems, and the same quantities are represented as the same vectors regardless of the differences in people, products, domains, organizations, nations and languages. We assume that the similarities of physical phenomena lead to similarities in the dimensions of quantities describing the phenomena, and propose to use this seven-dimensional vector for estimating the similarity of design knowledge from the viewpoint of physical phenomena. Based on this basic idea, we mathematically define similarity between two quantities using quantity dimensions. We prepared design knowledge examples and retrieval keys and conducted design knowledge retrieval and design knowledge similarity estimation by quantity dimension indexing and confirmed that we obtained adequate results without using a concept dictionary or thesaurus elaborated in advance, which are indispensable in the text approach.
A Computational Study on Turbulent Flow and Heat Transfer in a Strongly Curved RC/D = 0.65 Turbine Blade Cooling Passage
Authors: Martinez Lucci Jose , Amano R. S. , Guntur Krishna S.
Published: May 2009

It has been a common practice that serpentine cooling passages are used in gas turbine blade to enhance the cooling performance. Insufficient cooled blades are subject to oxidation, to cause creep rupture, and even to cause melting of the material. To control and improve temperature of the blade, we have to have a better understanding of flow behavior and heat transfer inside strongly curved U-bends. The interactions between secondary flows and separation lead to very complex flow patterns. To accurately simulate these flows and heat transfer, both refined turbulence models and higher-order numerical schemes are indispensable for turbine designers to improve the cooling performance. Previous studies have shown that the flow and heat transfer features through curved bends, even with moderate curvature, cannot be accurately simulated. It is the conventional belief and practice that the usage of a proper turbulence model and a reliable numerical method for achieving accurate computations. The three-dimensional turbulent flows and heat transfer inside a sharp U-bend are numerically studied by using a non-linear low-Reynolds number (low-Re) k-ω model in which the cubic terms are included to represent the effects of extra strain-rates such as streamline curvature and three-dimensionality on both turbulence normal and shear stresses. The finite volume difference method incorporated with the higher-order bounded interpolation scheme has been employed in the present study. For the purpose of comparison, the predictions with the linear low-Reynolds number k-ω model were also performed. The success of the present prediction indicates that the model can be applied to the flow and heat transfer through a coolant passage in an actual gas turbine blade. It is shown that the present non-linear model produces satisfactory predictions of the flow development inside the sharp U-bend comparing with linear Launder-Sharma model. In the present study, three turbulence models are used to predict Nysselt number distribution as well.
Wheel/Rail Two-Point Contact Geometry With Back-of-Flange Contact
Authors: Sugiyama Hiroyuki , Suda Yoshihiro
Published: May 2009

In this investigation, a numerical procedure that can be used for the three-dimensional analysis of wheel and rail contact geometry is developed using the constraint contact formulation. The locations of contact points are determined for given lateral and yaw displacements of a wheelset when one-point contact is considered for each wheel, while these two displacements are no longer independent when the two-point contact occurs. A systematic procedure for predicting the flange as well as the back-of-flange contact points is developed and used for the two-point contact analysis of wheel and rail. Numerical results that involve tread, flange, and back-of-flange contacts are presented in order to demonstrate the use of the contact algorithm developed in this investigation. In particular, the back-of-flange contact is discussed for assessing contact configurations of wheel and grooved rail in Light Rail Vehicle (LRV) applications.
Integrated Structure Decomposition, Optimization and Control Design
Authors: Butler Shaoluo L. , Dhingra Anoop K.
Published: May 2009

In this paper, an integrated optimization, controller design and reduced order finite element modeling based approach is presented for structural design. The proposed approach involves structure decomposition, subcontroller design, system controller assembly, and multiobjective optimization. The concept of structure decomposition with compatible and incompatible interfaces is presented for a control/optimum system problem, and developed for problems with compatible interfaces involving substructure controller design and multiobjective optimization. The substructure information obtained through finite element analysis is synthesized to reconstruct a reduced order model for the entire structure. Based on SSSC (Substructure Synthesis-Substructure Controller), a controller is designed for each substructure. The global controller is obtained by assembling all subcontrollers designed at the substructure level. A multiobjective optimum formulation is presented based on structure decomposition and controller design. Four objective functions are simultaneously optimized. These include a stability robustness index, structural weight, controller energy, and a controller performance index. Numerical examples are presented to demonstrate the effectiveness of the proposed methodology. Results obtained using the proposed approach are compared with those obtained from optimization of the entire structure.
Nonlinear Dampers Utilizing Polynomial and Step Characteristics
Authors: Inoue Tsuyoshi , Tsukamoto Sho , Takagi Kentaro , Ishida Yukio
Published: May 2009

Conventional linear viscous damper has the trade-off characteristics between the vibration suppression effect of peak resonances and the increase of vibration at the frequency ranges except the resonance frequencies. This paper investigates the nonlinear dampers to solve such problems and proposes two kinds of nonlinear dampers, a polynomial function type and a step function type. The two-degrees-of-freedom system is considered and the proposed nonlinear damper is installed between the mass points. The nonlinear theoretical analysis is performed for investigating the vibration suppression effect of the polynomial type damper, and some of the polynomial damping terms which can resolve the trade-off disadvantages are found. Moreover this study discusses the physical interpretations of such vibration suppression effects of polynomial type nonlinear dampers, and proposes a nonlinear damper with step function characteristics by extending the idea of the polynomial dampers. The effectiveness of the proposed nonlinear damper is demonstrated experimentally using a magnetic damper which realizes the nonlinear property.
Effects of Vessel Configurations on the Damping Effects of an Impact Damper Using an Elasto-Plastic Material
Authors: Ito Tomohiro , Fujita Katsuhisa , Okaya Naotoshi
Published: May 2009

In this study, the damping effects of an impact damper which consists of a vessel and elasto-plastic balls are evaluated. Lead is employed as an elasto-plastic material. Numerical simulations are performed based on a discrete element method. In the numerical simulations, the impact force modeling is modified so as that the elasto-plasticity of the material can be considered. And the rotation of a particle is also considered to simulate the actual particle behaviors at the collision. Frequency responses of the vessel and the damping effect of the damper are evaluated for 2 kinds of impact force models. Also, the effects of vessel dimensions, vessel configurations and the excitation directions are investigated. As a result, the effects of the above mentioned parameters are clarified.
Passive Vibration Control of Multi Buildings Connected With Hybrid Magnetorheological Damper
Authors: Iio Chinori , Dohnal Fadi , Seto Kazuto , Watanabe Toru
Published: May 2009

In this paper we propose a passive vibration control method for multiple high-rise buildings arranged in parallel. Using this method, it is possible to control vibrations of highrise buildings against strong winds and large earthquakes. In this study, two model buildings are connected with hybrid MR (Magneto-Rheological) damper. The objective of this research is to control the first and second bending modes of each building using the proposed method. The control effect is evaluated by exciting the base of the structures by time response and measuring the frequency response of the structures. Both simulation and experimental results show that fairly good control performance has been achieved by this method.
Using Tolerance-Maps to Generate Frequency Distributions of Clearance for Tab-Slot Assemblies
Authors: Ameta Gaurav , Davidson Joseph K. , Shah Jami J.
Published: May 2009

A new mathematical model for representing the geometric variations of tabs/slots is extended to include probabilistic representations of 1-D clearance which can be determined from multi-dimensional variations of the medial plane for a slot or a tab, and from variations of both medial planes in a tab-slot assembly. The model is compatible with the ASME/ANSI/ISO Standards for geometric tolerances. Central to the new model is a Tolerance-Map (T-Map), a hypothetical volume of points that models the range of 3-D variations in location and orientation for a segment of a plane (the medial plane), which can arise from tolerances on size, position, orientation, and form. Here it is extended to model the increases in yield that occur when the optional maximum material condition (MMC) is specified and when tolerances are assigned statistically rather than on a worst-case basis. The frequency distribution of 1-D clearance is decomposed into manufacturing bias, i.e. toward certain regions of a Tolerance-Map, and into a geometric bias that can be computed from the geometry of multidimensional T-Maps. Although the probabilistic representation in this paper is built from geometric bias, and it is presumed that manufacturing bias is uniform, the method is robust enough to include manufacturing bias in the future. Geometric bias alone shows a greater likelihood of small clearances than large clearances between an assembled tab and slot. A comparison is made between the effects of choosing the optional MMC and not choosing it with the tolerance that determines the allowable variations in position of a slot.
Aeroelastic Stability of Wide Webs and Narrow Ribbons
Authors: Bidkar Rahul A. , Raman Arvind , Bajaj Anil K.
Published: May 2009

Uni-axially tensioned wide webs and narrow ribbons commonly used in the paper-handling, textile, sheet-metal, and plastics industries are known to undergo large amplitude vibrations characterized as aeroelastic flutter. The aeroelastic stability of stationary wide webs and narrow ribbons coupled with fluid flow across the free edges of the web or ribbon is investigated in this article. The web or ribbon is modeled as a uni-axially tensioned Kirchhoff plate with vanishingly small bending stiffness. The 3D unsteady fluid flow surrounding the web or ribbon is evaluated numerically by using the vortex-lattice method. Wide webs are mainly found to exhibit the divergence instability. For some values of the applied tension, the clustered web modes exhibit frequency curve veering accompanied by a weak flutter instability before the occurrence of the divergence instability. The applied tension plays a critical role in deciding the type of instability in narrow ribbons. In cross flow, depending on the applied tension, narrow ribbons undergo flutter instability or divergence instability or the simultaneous onset of both instabilities.
Modification of Friction-Induced Instability in a Disk System Through Dither Excitation Forces
Authors: Michaux Michael A. , Ferri Al , Cunefare Kenneth A.
Published: May 2009

This paper employs a continuous rotor model and a contacting SDOF system to examine dither’s role in stabilizing friction-induced oscillations. The disc rotor is modeled by a thin, clamped-free annular plate. Under the action of tangential dither, the frictional contact load is represented by a sinusoidally-varying follower force. The stability of the combined system, with and without dither signals, is assessed using multiple-scale analysis and Floquet theory. It is shown that dither is capable of quenching instabilities at some rotor speeds while at the same time producing new instabilities at other rotor speeds. The results suggest that one mechanism by which dither can suppress squeal is by changing the rotor speeds at which squeal vibrations occur.
Development of a Mechanically Coupled, 6-Axis Force-Torque Sensor for Humanoid Robots
Authors: Son A-Ram , Oh Jum-Ho , Noh Tae-Yang , Yoo Wan-Suk
Published: May 2009

For better walking performance of humanoid robots, the measure of ZMP is inevitable. The traditional and basic tool for ZMP measurement is to use a force-torque sensor. A 6-axis force-torque sensor can measure all direction’s force data, 3 forces and 3 torques applied to the body. This paper describes mechanically coupled design of a 6-axis force-torque sensor using strain gauges especially for humanoid robots. In mechanically coupled sensors, force data can not be obtained directly from strain signals. Instead output data should be calculated through a additional matrix calculation. Here we suggested a new design method of a small size 6-axis force-torque sensor module for humanoid robots. In this paper, we proposed design guide of the sensor’s structure design, amplitude circuit, and details for the data acquisition board for humanoid robots.
Design for Product Adaptability
Authors: Li Y. , Xue D. , Gu P.
Published: May 2009

Adaptable design is a new design paradigm to create designs and products that can be easily changed to satisfy different requirements. Adaptable design aims at identifying the designs and products considering functionality, manufacturing efforts, customization and environment friendliness. This research focuses on adaptable design considering product adaptability. In this work, product adaptability is evaluated by three measures including extendibility of functions, upgradeability of modules, and customizability of components. Various design candidates created in adaptable design are evaluated by different life-cycle evaluation measures including product adaptability of design, part and assembly costs of manufacturing, and operationability by customers. Since different evaluation measures are modeled in different units, the grey relational analysis method is employed to integrate the different evaluation measures for prioritizing different design candidates. A case study is given to demonstrate the effectiveness of the introduced adaptable design approach.
Cracked Rotor Diagnostics Using Soft Computing
Authors: Samanta B. , Nataraj C.
Published: May 2009

A study is presented for detection and diagnostics of cracked rotors using soft computing techniques like adaptive neuro-fuzzy inference system (ANFIS), artificial neural networks (ANN) and genetic algorithms (GA). A simple model for a cracked rotor is used to simulate its transient response during startup for different levels of cracks. The transient response is processed through continuous wavelet transform (CWT) to extract time-frequency features for the normal and cracked conditions of the rotor. Several features including the wavelet energy distributions and the grey moment vectors (GMV) of the CWT scalograms are used as inputs for diagnosis of crack level. The parameters of the classifiers, ANFIS and ANN, along with the features from wavelet energy distribution and grey moment vectors are selected using GA maximizing the diagnostic success. The classifiers are trained with a subset of the data with known crack levels and tested using the other set of data (testing data), not used in training. The procedure is illustrated using the simulation data of a simple de Laval rotor with a ‘breathing’ crack for different crack levels during run-up through its critical speed. A comparison of diagnostic performance for the classifiers is presented. Results show the effectiveness of the proposed approach in detection and diagnosis of cracked rotors.
A Perspective of Hierarchical Layout Design Optimization for Highly Packaged Equipments
Authors: Fujita Kikuo , Kuriyama Masanori , Suyama Takashi
Published: May 2009

This paper discusses a perspective of hierarchical layout design optimization for highly packaged equipments and demonstrates an implementation of an optimization algorithm with a simplified case study. First, the Pareto optimality of subsystem-level shape design against the optimality of system-level shape design is extracted through two-level hierarchical formulation of layout design problems. Then, a computational design algorithm is developed for a class of two-dimensional layout design problems of rectangles, some of which are the results of similar problems defined in its sub-levels. The algorithm represents the layout topology with sequence-pair and the shape of each module or component with the aspect ratio, and optimizes them with genetic algorithms. The Pareto optimality of sub-levels is handled with the functionality of multi-objective optimization of genetic algorithms, in which a set of Pareto are simultaneously generated. Top-level and sub-level layout problems are coordinated through exchange of preferable ranges of shapes and layout. A case study is explored under the developed algorithm. The promises and limitations of the proposed framework is briefly discussed for defining the future works.
Control of a Haptic Interface and a Micromachining Setup With an Open Source Real-Time System
Authors: Samur Evren , Spaelter Ulrich , Flaction Lionel , Maillard Pascal , Bleuler Hannes , Wu¨thrich Rolf
Published: May 2009

Open source software have evolved into powerful tools for real-time control of mechatronic systems. They are of interest for academic purposes, as they promise high flexibility at low cost. In this paper, we investigate the performance of an open source control architecture based on the Linux Real-Time Application Interface (RTAI) through two applications, a haptic interface for surgery simulation and a setup for the micromachining of glass. Both applications demand a compact real-time system with sufficient precision (i.e. low jitter) for online process control and data acquisition. The real-time control has been realized on a laptop with a USB-port data acquisition card. Performance measurement results show that high quality real-time control can be performed up to 2kHz via USB communication, which is sufficient for a large range of robotic or mechatronic applications. Drawbacks like the need for considerable knowledge of Linux internals for successful installation as well as the current limitations are discussed and strategies are proposed to overcome these. Both setups are currently being used for ongoing research as well as for educational purposes.