bluuebunny/crossref_metadata_2025 huggingface dataset:
Three-Dimensional Fractional Derivative Models for Finite Deformation
Authors: Fukunaga Masataka , Shimizu Nobuyuki
Published: June 2012

Fractional derivative stress-strain relations are derived for compressible viscoelastic materials based on the continuum mechanics. Several types of stress tensor and strain tensors are specified to describe the dynamics of continuous media. Consequently there are many equivalent expressions of stress-strain relations. If memory effect is not taken into account, these relations are equivalently transformed from one to another by suitable tensor operations. However, if memory effect is included in the mechanics of the materials, different types of stress-strain relations can be derived depending on the choice of the type of stress tensor, or equivalently the choice of the strain energy function. In this paper, several types of fractional derivative stress-strain relations are proposed.
Failure Analysis of a High Pressure Descaling Pump Using Envelope Analysis
Authors: Shao Yimin , Yu Wennian , Chen Qing , Xiao Huifang , Yu Xiangzhi
Published: June 2012

A high pressure descaling pump was used to remove scale in a hot rolled band furnace. This pump was the key piece of equipment in this process which maintained the surface quality of the hot rolled band steel. Over a period of three years one pump continued to work normally, but the other pump vibrated vigorously. The motor, pump and the other system equipment were changed repeatedly, but the abnormal vibration was not eliminated. Vibration data from the two pumps was obtained, the modulation phenomenon existed in the vibration signal caused by the gear coupling misalignment was found, thus the envelope analysis based on the Hilbert transform was presented to demodulate the vibration signal. The frequency spectrum of the demodulated signal showed that the second order frequency characteristic was more obvious, which effectively revealed the fault information related with the gear coupling misalignment. It was found that the abnormal vibration was caused by coupling misalignment between the motor and the pump. After applying a more advanced alignment technique to thoroughly eliminate the misalignment in the coupling, the vibration was considerably reduced and the pump could work normally. This convincingly verified our analysis results and would dramatically reduce the ongoing maintenance cost for the descaling pump system.
Heat Generation, Power Transmission Efficiency, and Life of Plastic Worm and Helical Wheels Meshed With Steel Worm
Authors: Koide Takao , Takahashi Mikio , Takahashi Hideo , Miyachika Kouitsu
Published: June 2012

This paper describes the heat generation, power transmission efficiency, and life of plastic helical and worm wheels meshed with a steel worm. A machine for testing plastic worm gears was developed, in which the center distance and shaft angle are variable, and by which the transmission efficiency can be measured. Experiments were performed using plastic helical and worm wheels and steel worms under no-lubrication condition. Polyacetal homopolymer and copolymer were used as wheel materials. The tooth temperatures of the plastic helical and worm wheels and the torques of the worm and wheel shafts were measured. The failure mode for plastic helical and worm wheels; the temperature of the wheel teeth; the transmission efficiencies between meshing gear teeth; and the lives of plastic wheels were determined. The effects of backlash and shaft angle on the life of plastic wheels were also determined.
Pitch Configurations: Definitions, Analytical and Computer Synthesis
Authors: Abadjiev Valentin , Abadjieva Emilia , Petrova Dochka
Published: June 2012

The synthesis and the design of spatial gears with crossed axes are based on solving of two problems: synthesis of the pitch surfaces and synthesis of the active tooth surfaces. The solution of the problem for synthesis of the pitch surfaces with different form and geometry serves the design of the gears blanks, as well as the calculation of the active tooth surfaces of the gears teeth. The usage of the pitch circles as an alternative of the pitch surfaces makes the process of the synthesis and the design of the hyperboloid gears more clearly from a geometric viewpoint. It is highly important when designing hyperboloid gears with non-orthogonal crossed axes and internally mating gears. Thus, the introduction of the pitch circles helps creating innovative kinds of spatial gears with crossed axes. The examined pitch configurations, synthesized by a computer, define the basic geometric characteristics of the gears with crossed axes of rotation. In the most common case, the pitch configurations do not coincide with elements of the axodes of this class of gear mechanisms, the axodes being hyperboloids of revolution.
Building Bridges for Engineering Education: The Experience of Partnership With Building Industry for Sustainable Solutions
Authors: Zeiler Wim
Published: June 2012

Due to a demand for more sustainability, with as ultimate goal Zero Emission Buildings, building design becomes more complex. Building design transfers from a mainly architect led process into a approach for multi-disciplinary design teams to cope with the growing complexity of the process. A supportive design method was developed in cooperation with the Dutch professional organizations of architects and consulting engineers. The design method provides overview and helps to structure the communication and reflection between design team members. The design method is focused on sustainability and the creation of sustainable solutions in the conceptual phase of building design. After testing the method in workshops as part of a training program in industry, the design method was transferred and applied at the department of architecture for master students for their multidisciplinary Master project Integral Design. The workshops became part of the permanent professional education program of the Dutch society of architects, several in-company workshops for industry were held and a course is now being developed for the Dutch society of building services engineers. So the partnership with building industry let to the developed design support method which acted as a kind of bridge for engineering education.
Five Position Synthesis of a Slider-Crank Function Generator
Authors: Plecnik Mark M. , McCarthy J. Michael
Published: June 2012

In this paper, we present a synthesis procedure for the coupler link of a planar slider-crank linkage in order to coordinate input by a linear actuator with the rotation of an output crank. This problem can be formulated in a manner similar to the synthesis of a five position RR coupler link. It is well-known that the resulting equations can produce branching solutions that are not useful. This is addressed by introducing tolerances for the input and output values of the specified task function. The proposed synthesis procedure is then executed on two examples. In the first example, a survey of solutions for tolerance zones of increasing size is conducted. In this example we find that a tolerance zone of 5% of the desired full range results in a number of useful task functions and usable slider-crank function generators. To demonstrate the use of these results, we present an example design for the actuator of the shovel of a front-end loader.
Integrated Numerical Model for Thermohydrodynamic Analysis of Bump-Type Foil Bearings
Authors: Feng Kai , Kaneko Shigehiko , Houjoh Haruo
Published: June 2012

This investigation presents a thermohydrodynamic (THD) analysis for bump-type foil bearings. Two basic equations, the generalized Reynolds equation and the energy equation, are simultaneously solved for the air pressure and generated heat due to the viscous shearing action in the air film. The compliant foil strip is described as a link-spring structure. The calculated foil deflection is coupled into the solution of the two basic equations to account for its effect on the film thickness. This model accounts for heat convection in the air film region and the material property variations of the lubricant air due to the temperature rise, heat convection with the cooling air, heat conduction between the solid components, heat transfer at the surface of the solid components, and thermal expansion of the bearing components as well as change in the bump foil elasticity. The airflow within the air film is a distinctive characteristic of bump-type foil bearings (BTFBs) compared to normal oil bearings because the top foil detaches at sub-ambient regions. The unique airflow is also taken into consideration in this model to modify the thermal boundary condition of the air film. Data from a published experimental investigation is used to validate the mathematical model. The predicted bearing temperatures, as well as the bearing load, agree well with the experimental data. The effects of ambient temperature on BTFB performance are discussed with the THD model. With increased ambient temperature, the influence of the bearing clearance changes, because the thermal growth of the bearing components is more significant than the decrease of the foil elasticity. Therefore, the thermal expansion coefficients of the bearing components should be considered during bearing design. The temperature profile within the foil bearing is predicted and compared with published tested temperature values. The calculated temperature correlates well with the experimental data at most of the positions. The deviation between the two values at the bearing-load position is demonstrated to be less than 10.3%.
Early BOM Derivation From Requirement Specifications by Reusing Product Knowledge
Authors: Maltzahn Sebastian , Anderl Reiner
Published: June 2012

Over the years a lot of strategies emerged to enhance efficiency throughout the product lifecycle of complex products: knowledge management, platform and module strategies as well as integrated requirements management are only a few of the existing product lifecycle management (PLM) strategies. An integrated product model is seen as the backbone of PLM management strategies. Most product structuring approaches propose to develop a functional structure first, considering the given requirements. From this a product structure is derived, which is finally filled with developed parts and assemblies (bill of material, BOM). In early product development phases there has to be a common understanding among the involved departments and domains about the future product appearance. Products based on platform or modular strategies have a high proportion of reused parts and assemblies. Besides, new parts have to be identified, prioritized and developed according to their priority. For this process a reliable, interdisciplinary product structure is essential. Hence, an early bill of material is used to integrate engineering tasks in early development phases and to shorten identification as well as prioritization efforts. This paper proposes an approach to derive an early bill of material from requirement specifications semi automatically.
A Polynomial Chaos Based Bayesian Inference Method With Uncertain Hyper-Parameters
Authors: Tagade Piyush M. , Choi Han-Lim
Published: June 2012

This paper proposes stochastic spectral representation for Bayesian calibration of computer simulators with parametric and model structure uncertainty with unknown/poorly known prior hyper-parameters. The methodology is specifically developed for calibration of simulators with spatially/temporally varying parameters. Uncertainty in parameters and model structure is represented using independent stationary Gaussian processes with uncertain hyper-parameters. Gaussian processes are spectrally represented using Karhunnen-Loeve expansion. A methodology based on decomposition of parametric space and orthogonal polynomials defined on the decomposed space is developed for evaluating coefficients of Karhunnen-Loeve expansion of Gaussian process with uncertain hyper-parameters. Galerkin projection method is used to evaluate the resultant stochastic spectral decomposition of predicted system response. Bayesian inference is used to update the prior probability distribution of the polynomial chaos basis. The proposed method is demonstrated for calibration of a simulator of quasi-one dimensional flow through a convergent-divergent nozzle.
Initialization of Riemann-Liouville and Caputo Fractional Derivatives
Authors: Trigeassou Jean-Claude , Maamri Nezha , Oustaloup Alain
Published: June 2012

Riemann-Liouville and Caputo fractional derivatives are fundamentally related to fractional integration operators. Consequently, the initial conditions of fractional derivatives are the frequency distributed and infinite dimensional state vector of fractional integrators. The paper is dedicated to the estimation of these initial conditions and to the validation of the initialization problem based on this distributed state vector. Numerical simulations applied to Riemann-Liouville and Caputo derivatives demonstrate that the initial conditions problem can be solved thanks to the estimation of the initial state vector of the fractional integrator.
Stiffness Design for Compliant Manipulators Based on Dynamics Analysis of the Impact Configuration
Authors: Gan Dongming , Tsagarakis Nikos G. , Dai Jian S. , Caldwell Darwin G.
Published: June 2012

This paper presents a study on setting the joint stiffness for compliant robots in order to protect the actuators when the arm comes up against impact. System dynamic equations of compliant manipulators integrated with impact model are linearized to identify the maximum joint torques in the impact. Based on this, different directions of end-effector velocity and impact normal in different configurations in the robot workspace are calculated based on a given magnitude of end-effector velocity. By tuning the stiffness for each compliant joint to ensure the joint torque does not exceed the maximum value of the actuator, candidate stiffness values are obtained to make the compliant actuators safe in all cases when the robot end-effector moves with a velocity within the fixed magnitude value used in the calculation. The theory and procedure are firstly laid and demonstrated in a 1-DOF planar manipulator, then the work is applied to a 2-DOF compliant manipulator and the candidate stiffness is obtained based on the method.
Free Vibration Analysis of FGM Beams With Different Boundary Conditions Using RKPM Meshless Method
Authors: Saljooghi R. , Ahmadian M. T.
Published: June 2012

This paper presents free vibration analysis of functionally graded material (FGM) beams with different boundary conditions, using RKPM (Reproducing Kernel Particle Method), which is a meshless method. System of equations of motion is derived by using Lagrange’s method under the assumption of Euler-Bernoulli beam theory. Boundary conditions of beam are taken into account by using Lagrange multipliers. It is assumed that material properties of the beam vary continuously in the thickness direction according to the power-law form. RKPM is applied to obtain eigenvalue equation of vibration and natural frequencies are obtained. It should be noted that for special cases where the beam is uniform, natural frequencies match nicely with theoretical prediction.
On Failure Problem of Gears Made From Very High Strength Steel
Authors: Kubo Aizoh
Published: June 2012

Some typical examples of failure of gears made from very high strength steel are shown and its trigger and whose causes are discussed: Many of such failure are triggered by tooth side edge contact or tooth tip edge contact and meshing-in of the wear debris. The limit of validity of the traditional methods for load carrying capacity of gears exists in the fact that they are based on the theory of contact of tooth flanks that realize conjugate or almost conjugate action of gears. To be able to design reliable gears made from very high strength steel, a principle is shown that suggests a new method for tooth form modification and of longitudinal crowing modification to avoid such failure. Metallurgical problem of gear material and special heat treatment aiming high surface hardness is also discussed.
Design Procedure and Rules to Configure Lower Limb Prosthesis
Authors: Colombo Giorgio , Gabbiadini Stella , Regazzoni Daniele , Rizzi Caterina
Published: June 2012

Modular lower limb prosthesis is composed by custom-fit parts, such as the socket containing the residual limb, and standard components available on market, such as knee or foot. For both custom and standard parts the support offered by existing design tools is not efficient or integrated enough and, as a result, most prosthetists do not use computer-aided tools and still rely only on their personal expertise. This paper presents an approach to design and configure complete lower limb prosthesis for transfemoral and transtibial amputees, using patient’s digital data (e.g., residual limb model acquired by MRI) and specification sheets of components. The ultimate goal is to realise a virtual laboratory where the technicians can design lower limb prosthesis guided step by step by the system. We have identified key patient’s characteristics guiding the prosthetist during the four main steps of the production process: acquiring patient’s data, socket modelling, standard components selection and prosthesis assembly and check. The developed innovative framework integrates different tools to guide the technicians during each design task providing specific knowledge and rules. Thus, it allows a quicker and easier definition of the virtual prosthesis, on which virtual test could be performed (e.g., pressure distribution on residual limb, gait evaluation) in order to be able to realize the definitive prosthesis at the first attempt. The results have been evaluated and validated with the technical staff of a certified orthopaedic laboratory.
Using Economic Input-Output Life Cycle Assessment to Guide Sustainable Design
Authors: Michalek Jeremy J. , Hendrickson Chris T. , Cagan Jonathan
Published: June 2012

Successful design for the environment (DfE) requires the designer to understand the life cycle impact of design decisions. However, estimating life cycle implications of design choices using traditional process-based life cycle assessment (LCA) is typically too time- and resource-intensive to be practical as part of the design process. We examine the use of economic input-output life cycle assessment (EIO-LCA) as a tool to support sustainable design by helping the designer to quickly determine which aspects of the product dominate its lifetime emissions. Compared to traditional process-based LCA, EIO-LCA produces estimates at a more aggregated level using data on economic transactions and emissions from each sector of the economy. However, EIO-LCA computes full supply chain emissions associated with output from a particular sector in seconds, and for many products these aggregate-level data are sufficient to determine which aspects of the product dominate and to guide sustainable design efforts. We explore two product design examples where a quick scoping exercise with EIO-LCA identifies clear areas of focus for design improvement and innovation.
Towards Whole-Arm Statics
Authors: Lauzier Nicolas , Gosselin Cle´ment
Published: June 2012

In this paper, a novel approach is proposed to compute the maximum contact force that can be applied by a manipulator at any point on its external surface. The approach consists in the approximation of the robot’s external surface by simple primitives for which the position and normal direction can easily be expressed analytically for any point on the surface. This approach is also used to compute analytically the boundaries of the zones on the external surface where the achievable force exceeds a predetermined threshold. A method is developed for determining the limit joint torques which ensure that the achievable force cannot exceed a predetermined magnitude for any point on the primitives. Specific equations are developed for two types of primitives (parallelogram and cylinder) along with generic procedures applicable to any shape. An example is presented to illustrate how the proposed procedures can be applied for the solution of a typical problem. Finally, the applicability and limitations of this approach are discussed. A potential application for this work is to provide information on a robot’s dangerousness to its controller in order to improve safety.
Trimodal Tapping-Mode Atomic Force Microscopy: A Possible Method for Simultaneous Measurement of Conservative and Dissipative Interactions
Authors: Chawla Gaurav , Solares Santiago D.
Published: June 2012

Multifrequency Atomic Force Microscopy (AFM) techniques, where the cantilever oscillation is measured and sometimes driven at multiple frequencies, have become an active research topic in recent years. This is in part because these methods can provide increased compositional contrast during surface characterization. Since 2004 bimodal AFM imaging has been used extensively to complement the information that can be obtained using the standard single-frequency tapping-mode operation. More recently we have implemented a trimodal tapping-mode scheme, in which we have incorporated a frequency-modulated third eigenmode into bimodal tapping-mode operation in order to acquire topography, phase and frequency shift information simultaneously. We have also studied numerically the effect of different levels of sample stiffness, tip-sample dissipative forces, oscillation amplitudes for each of the eigenmodes and cantilever rest positions above the sample on the frequency response of the higher eigenmodes in bimodal and trimodal operations. Here we explore the ability to separate conservative and dissipative effects using the different channels available in trimodal operation.
On the Analysis of Periodic Delay Differential Equations With Discontinuous Distributed Delays
Authors: Bobrenkov Oleg A. , Nazari Morad , Butcher Eric A.
Published: June 2012

In this paper, the analysis of delay differential equations with periodic coefficients and discontinuous distributed delay is carried out through discretization by Chebyshev spectral continuous time approximation (ChSCTA). These features are introduced in the delayed Mathieu equation with discontinuous distributed delay used as an illustrative example. The efficiency of the process of stability analysis is improved by using shifted Chebyshev polynomials for computing the monodromy matrix, as well as the adaptive meshing of the parameter plane. An idea for a method for numerical integration of periodic DDEs with discontinuous distributed delay based on existing MATLAB functions is proposed.
A Novel Design of Iterative Learning Observer for Fault Estimation
Authors: Liu Chun-Mei , Yang Han-Long , Chen Wen
Published: June 2012

This paper is to present a novel design of the Iterative Learning Observer (ILO) for the purpose of fault estimation. With the new design of ILO, initial oscillation of the fault estimate is dramatically reduced. The learning accuracy is accordingly improved. Convergence of the ILO to the system is proved and simulation study is conducted. It shows that accurate fault estimation can be performed by the new ILO.
Designing a New Type of Energy Trap: A Classical Analog of Quantum Landau-Zener Tunneling
Authors: Vakakis Alexander F. , Sigalov Grigori , Mane Mercedes , Bergman Lawrence A. , Manevitch Leonid I. , Kosevich Yury A.
Published: June 2012

We present a novel type of energy trap providing targeted energy transfer (TET) in a system of weakly coupled pendulums. Our approach is based on the analogy, presented in [1, 2], between the behavior of two weakly coupled classical parametric pendulums and nonadiabatic Landau-Zener tunneling (LZT) in a two-state quantum system. The two systems, however dissimilar, turn out to be described by the same asymptotic equations. Well-known properties of LZT allow us to predict the possibility of efficient irreversible transfer of vibration energy from one subsystem to another in mechanical systems. The TET takes place when the eigenfrequency of a subsystem changes in time so that the coupled subsystems pass through internal resonance. The existence of such a phenomenon is not restricted to coupled pendulums but is inherent to a wide class of both linear and nonlinear parametric oscillatory systems. This opens up the possibility of designing new types of energy traps and absorbers for the dynamic protection of various mechanical systems. Experimental data obtained in this work corroborate theoretical predictions.
Isogeometric Shape Design Sensitivity Analysis Using Mixed Transformation Method for Kronecker Delta Property
Authors: Cho Seonho , Koo Bon-yong , Yoon Minho , Lee Seung-Wook , Ha Youn Doh
Published: June 2012

The isogeometric method is very effective in shape design optimization due to its effectiveness through the easy design parameterization and accurate sensitivities considering the higher order geometric terms. Due to non-interpolatory property of the NUBRS basis functions, however, the treatment of essential boundary condition is not as straightforward in the isogeometric analysis as in the finite element analysis. Taking advantages of the transformation method developed in meshfree methods, we investigate the isogeometric shape sensitivity analysis with the treatment of essential boundary conditions. Using the property that isogeometric basis functions do not depend on design changes, the transformed shape sensitivity equation is developed and verified for the problem having the essential boundary conditions. Numerical costs to construct the transformed basis function are not as much as the meshfree methods due to the NURBS property that only boundary nodes have their supports on the boundary. Through demonstrative numerical examples having the essential boundary conditions, the effectiveness of proposed design sensitivity analysis is verified.
A Model of Caterpillar Locomotion Based on Assur Tensegrity Structures
Authors: Orki Omer , Shai Offer , Ayali Amir , Ben-Hanan Uri
Published: June 2012

This paper presents an ongoing project aiming at building a robot composed of Assur tensegrity structures, which mimics caterpillar locomotion. Caterpillars are soft-bodied animals capable of making complex movements with astonishing fault-tolerance. In our model, each caterpillar segment is represented by a 2D tensegrity triad consisting of two bars connected by two cables and a strut. The cables represent the major longitudinal muscles of the caterpillar, while the strut represents hydrostatic pressure. The control scheme in this model is divided into localized low-level controllers and a high-level control unit. The unique engineering properties of Assur tensegrity structures, which were mathematically proved last year, together with the suggested control algorithm provide the model with robotic softness. Moreover, the degree of softness can be continuously changed during simulation, making this model suitable for simulation of soft-bodied caterpillars as well as other types of soft animals.
Analytical Model, Multibody Simulation and Validation Tests for Dynamical Instability Reduction of a Grinding Machine With Dampers
Authors: Braccesi Claudio , Cianetti Filippo , Landi Luca
Published: June 2012

The subject of the present paper is the dynamic instability (chatter) of machine tools. The chatter is a self-regenerative oscillatory phenomenon related to the tool-work piece interaction during the process; that leads to an incorrect surface finishing of work piece. In big machine tools passive damping components are often introduced in order to reduce the chatter. Those passive components have to be tuned to the natural frequency of chatter vibrations, measured experimentally or predicted theoretically. In this paper the reduction of chatter for a planar grinding machine is described. At first, a theoretical model for the prediction of the general chatter for planar milling will be described through two lumped parameters and a multi body numerical model. Moreover the correlation between the theoretical model and experimental measures in terms of receptance will be presented. Two different kinds of passive damper systems will be theoretically introduced. In the end, the experimental results for chatter reduction obtained with the passive dampers introduction will be shown.
Analysis of Micro-Elastohydrodynamic Lubrication and Surface Fatigue in Gear Micropitting Tests
Authors: Evans H. P. , Snidle R. W. , Sharif K. J.
Published: June 2012

The paper describes results obtained from the micro-elastohydrodynamic lubrication (micro-EHL) modelling of the gear tooth contacts used in micropitting tests together with contact fatigue and damage accumulation analysis of the surfaces involved. Tooth surface profiles were acquired from pairs of helical test gears and micro-EHL simulations were performed corresponding to surfaces that actually came into contact during the meshing cycle. Fatigue and damage accumulation analysis shows that predicted damage is concentrated close to the tooth surfaces and this strongly suggests that micropitting damage arises from fatigue at the asperity contact level.
A Piezoelectric PZT Ceramic Multilayer Stack for Energy Harvesting Under Dynamic Forces
Authors: Xu Tian-Bing , Siochi Emilie J. , Kang Jin Ho , Zuo Lei , Zhou Wanlu , Tang Xiudong , Jiang Xiaoning
Published: June 2012

In this paper, we report the study of a “33” longitudinal mode, piezoelectric PZT ceramic multilayer stack (PZT-Stack) with high effective piezoelectric coefficient for broader bandwidth high-performance piezoelectric energy harvesting transducers (PEHTs). The PZT-Stack is composed of 300 layers of 0.1 mm thick PZT plates, with overall dimensions of 32.4 mm × 7.0 mm × 7.0 mm. Experiments were carried out with dynamic forces in a broad bandwidth ranging from 0.5 Hz to 25 kHz. The measured results show that the effective piezoelectric coefficients (EPC, deff) of the PZT-stack is about 1 × 105 pC/N at off-resonance frequencies and 1.39 × 106 pC/N at resonance, which is order of magnitude larger than that of traditional PEHTs. The EPC do not change significantly with applied dynamic forces having root mean square (RMS) values ranging from 1 N to 40 N. In resonance mode, 231 mW of electrical power was harvested at 2,479 Hz with a dynamic force of 11.6 Nrms, and 7.6 mW of electrical power was generated at a frequency of 2,114 Hz with 1 Nrms dynamic force. In off-resonance mode, an electrical power of 18.7 mW was obtained at 680 Hz with a 40 Nrms dynamic force. A theoretical model of energy harvesting for the PZT-Stack was established. The modeled results matched well with experimental measurements. This study demonstrated that structures with high EPC enable PEHTs to harvest more electrical energy from mechanical vibrations or motions, suggesting an effective design for high-performance low-profile PEHTs with potential applications in military, aerospace, and portable electronics. In addition, this study provides a route for using piezoelectric multilayer stacks for active or semi-active adaptive control to damp, harvest or transform unwanted vibrations into useful electrical energy.
On Reflection Symmetry and Its Application to the Euler-Lagrange Equations in Fractional Mechanics
Authors: Klimek Malgorzata
Published: June 2012

We study the properties of fractional differentiation with respect to the reflection symmetry in a finite interval. The representation and integration formulas are derived for the symmetric and anti-symmetric fractional derivatives, both of the Riemann -Liouville and Caputo type. The action dependent on the left -sided Caputo derivatives of orders in range (1.2) is considered and we derive the Euler-Lagrange equations for the symmetric and anti-symmetric part of the trajectory. The procedure is illustrated with an example of the action dependent linearly on fractional velocities. For the obtained Euler-Lagrange system we discuss its localization resulting from the subsequent sym-metrization of the action.
On the Identification of Machine Settings for Gear Surface Topography Corrections
Authors: Gabiccini Marco , Artoni Alessio , Guiggiani Massimo
Published: June 2012

In this paper we set out to investigate the performances of some of the algorithms proposed in the gear literature for identifying the machine-settings required to obtain predesigned gear tooth surface topographies, or needed to compensate for flank form deviations of real teeth. For the ease of comparison, the problem is formulated as a nonlinear least-squares minimization, and the most widely employed algorithms are derived as particular cases. The algorithms included in the analysis are: (i) one-step methods; (ii) iterative methods; (iii) iterative methods with step control. The performance index is devised in their ability of returning practical solutions in the presence of: (i) strong model nonlinearities, (ii) ill-conditioning of the sensitivity matrix, (iii) demanding topographic shapes purposely selected. Instrumental here is an original classification of topographic modifications as either “simple” or “complex”, based on the SVD analysis of the sensitivity matrix. On the basis of the numerical tests documented, iterative techniques with step control seem the most convenient, due to reliability and robustness of the solutions produced. The generation process here considered is face-milling of hypoid gears, even though the methodology is general enough to cope with any gear cutting method requiring only some minor technical changes.
On the Constitutive Response Characterization for Composite Materials via Data-Driven Design Optimization
Authors: Michopoulos John G. , Hermanson John G. , Iliopoulos Athanasios , Lambrakos Samuel , Furukawa Tomonari
Published: June 2012

In the present paper we focus on demonstrating the use of design optimization for the constitutive characterization of anisotropic material systems such as polymer matrix composites, with or without damage. All approaches are based on the availability of experimental data originating from mechatronic material testing systems that can expose specimens to multidimensional loading paths and can automate the acquisition of data representing the excitation and response behavior of the specimens involved. Material characterization is achieved by minimizing the difference between experimentally measured and analytically computed system responses as described by strain fields and surface strain energy densities. A one dimensional model is presented first to elucidate the design optimization for the general non-linear constitutive response. Small and large strain formulations based on strain energy density decompositions are developed and utilized for determining the constitutive behavior of composite materials. Examples based on both synthetic and actual data demonstrate the successful application of design optimization for constitutive characterization.
Development of an Ontology for the Automatic Reconfiguration of a Vise-Type Fixture Device
Authors: Gmeiner Thomas , Shea Kristina
Published: June 2012

The need for reconfigurable manufacturing systems has long been recognized as a key factor to gain the necessary flexibility for economically producing customized products. Automation of the reconfiguration processes is a challenge both on the hardware and the software level. Addressing this issue in the field of fixture design, a new reconfigurable fixture device for a CNC milling machine has been developed. The developed vise contains interchangeable jaws enabling the secure fixture of a wide variety of workpiece geometries. To enable automated reconfiguration, a reasoning system is needed that can determine feasible fixture configurations based on the given workpiece and part as well as the available fixture components. In this paper, an ontology for representing fixture design and reconfiguration knowledge for a specific reconfigurable vise-type fixture is introduced. The creation of the ontology is based on a systematic building methodology to identify necessary concepts, attributes and relations within the domain. Using Description Logic as the representation formalism, core concept definitions and relations are formalized to evaluate the correctness and consistency of the ontology. The ontology is validated both on the informal and on the formal level by its ability to find feasible fixture configurations, i.e. appropriate jaw pairs to fix example workpieces. The paper concludes with a discussion of the results and future work.
Visual Attitude Estimation for Low-Cost Personal Remote Sensing Systems
Authors: Fromm Tobias , Di Long , Chen YangQuan , Voos Holger
Published: June 2012

Remote Sensing using unmanned aerial vehicles (UAV) is gathering a lot of attention at the moment by researchers and developers, especially in terms of low-cost aircrafts which still maintain sufficient accuracy and performance. This paper introduces a low-cost approach to increase airworthiness by using a forward-looking camera to estimate the attitude of a UAV. It not only focuses on using machine learning to classify ground and sky, but also uses image processing and software engineering methods to make it fault-tolerant and really applicable on a miniature UAV. Additionally, it is able to interface with an autopilot framework to being used productively on flight missions.
Loci Surface Guided Crystal Phase Transition Pathway Search
Authors: Crnkic Edin , He Lijuan , Wang Yan
Published: June 2012

Recently a periodic surface model was developed to assist geometric construction in computer-aided nano-design. This implicit surface model helps create super-porous nano structures parametrically and support crystal packing. In this paper, we propose a new approach for pathway search in phase transition simulation of crystal structures. The approach relies on the interpolation of periodic loci surface models. Respective periodic plane models are reconstructed from the positions of individual atoms at the initial and final states, and surface correspondence are found. With geometric constraints imposed based on physical and chemical properties of crystals, two surface interpolation methods are used to approximate the intermediate atom positions on the transition pathway in the full search of the minimum energy path. This hybrid approach integrates geometry information in configuration space and physics information to allow for efficient transition pathway search. The methods are demonstrated by examples of FeTi and VO2.
Multi-Discipline Design of a Wind Turbine
Authors: Vlahopoulos Nickolas , Kim Hong Yoon , Maki Kevin , Sbragio Ricardo
Published: June 2012

In this paper a Multi-Level System design (MLS) algorithm is presented and utilized for a wind turbine system analysis. The MLS guides the decision making process for designing a complex system where many alternatives and many mutually competing objectives and disciplines need to be considered and evaluated. Mathematical relationships between the design variables and the multiple discipline performance objectives are developed adaptively as the various design considerations are evaluated and as the design is being evolved. These relationships are employed for rewarding performance improvement during the decision making process by allocating more resources and influence to the disciplines which exhibit the improvement. Simulation tools developed by the National Renewable Energy Laboratory (NREL) are employed in the wind turbine design analysis. The Cost Of Energy (COE) comprises the overall system level objective, while performance improvements at two technical design disciplines are pursued at the same time. The optimal design of the blade geometry for maximum Annual Energy Production (AEP), and the structural design of the blade for minimum bending moment at the root of the blade comprise the two technical design disciplines. Scalar metamodels are developed for linking the design variables with the performance metrics associated with the design of the blade geometry. Main characteristics of the wind turbine, namely, the rotor diameter, the rotational speed, the maximum rated power, the hub height, the structural characteristics of the blade, and the geometric characteristics of the blade (distribution of thickness, twist angle, and chord) are employed as design variables for the overall design analysis. The optimization results and the physical insight which can be gained through a sensitivity analysis for the optimal configuration are presented and discussed.
Multidisciplinary Design Optimization of Ship Hull Forms Using Metamodels
Authors: He Jim , Hannapel Shari , Vlahopoulos Nickolas
Published: June 2012

Multidisciplinary optimization is a highly iterative process that requires a large number of function evaluations to evaluate objective functions and constraints. Metamodels for computationally expensive functions or simulations can be employed in the multidisciplinary optimization instead of the actual solvers resulting in significant computational savings. In this paper, metamodeling is applied to the multidisciplinary design optimization of a ship hull with resistance, seakeeping, and maneuvering performance analyses. At the top system level, a simple cost metric is defined to drive the overall design optimization process. Changes to the hull shape are reflected in the numerical model for resistance computations and in the simulations associated with the seakeeping and maneuvering disciplines. An automated process has been developed for propagating changes to the numerical (CFD) model for the resistance computations; this expedites the computations at the sample points used for developing the metamodels. The validity of employing metamodels instead of the actual solvers during the optimization is demonstrated by comparing the values of the objective functions and constraints at the optimum point when using the actual solvers and when using the metamodels.
An Eccentric Rotator as a Novel Design of a Nonlinear Energy Sink
Authors: Gendelman Oleg V. , Sigalov Grigori , Mane Mercedes , Bergman Lawrence A. , Vakakis Alexander F. , Manevitch Leonid I.
Published: June 2012

We introduce a novel type of the nonlinear energy sink (NES) designed as an eccentric mass rotating within a horizontal plane. The gravity is not a factor here, therefore such a rotator has no eigenfrequency and can inertially couple and resonate with any mode of the primary system. The dynamics of the system consisting of a primary linear oscillator and the eccentric rotator is rich beyond expectations and features multiple resonances and chaotic modes. A numerical study shows that the system, when subject to high impulsive loads, inevitably enters a 1:1 resonance that enables highly efficient targeted energy transfer from the primary mass to the NES. The results of an experimental investigation are in good agreement with the analytical and numerical estimates.
Capturing Interactions and Emergent Failure Behavior in Complex Engineered Systems at Multiple Scales
Authors: Papakonstantinou Nikolaos , Sierla Seppo , Jensen David C. , Tumer Irem Y.
Published: June 2012

Large complex systems exhibit complex nominal and failure behavior and understanding that behavior is critical to the accurate assessment of risk. However, this assessment is difficult to accomplish in the early design stage. Multiple subsystem interactions and emergent behavior further complicate early design risk analysis. The goal of this paper is to demonstrate necessary modifications of an existing function-based failure assessment tool for application to the large complex system design domain. Specifically, this paper demonstrates how specific adaptations to this early, qualitative approach to system behavioral simulation and analysis help overcome some of the challenges to large complex system design. In this paper, a boiling water nuclear reactor design serves as a motivating case study for showing how this approach can capture complex subsystem interactions, identify emergent behavior trends, and assess failures at both the component and system level.
Model Verification and Design of Speed Control System of Water Driven Stage
Authors: Nakao Yohichi , Sano Toshiaki , Nagashima Midori , Suzuki Kenji
Published: June 2012

The present paper describes a design of speed control system of the water driven stage that has been developed for a feed table of an ultra-precision machine tool. The stage has a piston-cylinder mechanism to drive a table of the stage. Since the piston-cylinder mechanism is used, the flow rate supplied to the piston-cylinder controls the speed of the table. For diamond turning applications, the constant feed motion of the stage is highly desirable in order for obtaining fine diamond-turned surfaces. In the present paper, mathematical models of the water driven stage and a flow control valve are introduced. Based on the derived models, a conventional P-I control system is then designed in order to achieve desired control performances, aiming no steady-state error and minimized extraneous disturbance effects on the response. Performances of the designed controller are studied through experiments and simulations.
The Robotic Swarm Concept in Fixtures for Transport Industry
Authors: Molfino Rezia M. , Zoppi Matteo
Published: June 2012

The paper faces the problem of improving the flexibility of the manufacturing plant by rising the level of reconfigurability and the intelligence of peri-robotics. In particular the results obtained within the SwarmItFIX research project are presented. They refer to the concept and realization of robotic swarm fixturing for the support of airplane and automotive body panels during their manufacturing.
Multi-Modal Vibration Energy Harvesting Using a Trapezoidal Plate
Authors: Arafa Mustafa H.
Published: June 2012

Vibration-based energy harvesters are usually designed to exhibit natural frequencies that match those of the excitation for maximum power output. This has spurred interest into the design of devices that respond to variable frequency sources. In this work, an electromagnetic energy harvester in the form of a base excited trapezoidal plate is proposed. The plate geometry is designed to achieve two closely spaced vibration modes in order to harvest energy across a broader bandwidth. The ensuing bending and twisting vibrations are utilized in this capacity by placing a magnet on the plate tip that moves past a stationary coil. A dynamic model is presented to predict the system performance and is verified experimentally.
Design of Non-Anthropomorphic Robotic Hands for Anthropomorphic Tasks
Authors: Simo-Serra Edgar , Moreno-Noguer Francesc , Perez-Gracia Alba
Published: June 2012

In this paper, we explore the idea of designing non-anthropomorphic multi-fingered robotic hands for tasks that replicate the motion of the human hand. Taking as input data a finite set of rigid-body positions for the five fingertips, we develop a method to perform dimensional synthesis for a kinematic chain with a tree structure, with five branches that share three common joints. We state the forward kinematics equations of relative displacements for each serial chain expressed as dual quaternions, and solve for up to five chains simultaneously to reach a number of positions along the hand trajectory. This is done using a hybrid global numerical solver that integrates a genetic algorithm and a Levenberg-Marquardt local optimizer. Although the number of candidate solutions in this problem is very high, the use of the genetic algorithm allows us to perform an exhaustive exploration of the solution space to obtain a set of solutions. We can then choose some of the solutions based on the specific task to perform. Note that these designs match the task exactly while generally having a finger design radically different from that of the human hand.