bluuebunny/crossref_metadata_2025 huggingface dataset:
Chaotic Vibrations on a Coupled Vibrating System of a Post-Buckled Cantilevered Beam and an Axial Vibrating Body Connected With a Stretched String
Authors: Maruyama Shinichi , Nagai Ken-ichi , Muto Kota , Yamaguchi Takao
Published: July 2010

Analytical results are presented on chaotic vibrations on a coupled vibrating system of a post-buckled cantilevered beam and an axial vibrating body connected with a stretched string. The string is stretched between the top end of the cantilevered beam and the axial vibrating body which consists of a mass and a spring. As an initial axial displacement is applied to the spring, the beam is buckled by the tensile force of the string. The main scope of this paper is to investigate the effects of the axial inertia of the vibrating body on the chaotic vibrations of the system. The dynamical model involves nonlinear geometrical coupling between the deformation and the axial force of the beam at the boundary. Furthermore, the problem includes the static buckling and the nonlinear vibration. By using the mode shape function, which was proposed by the senior author, as a coordinate function of the governing equations, nonlinear ordinary differential equations in multiple-degree-of-freedom system are derived by the modified Galerkin procedure. Periodic responses of the beam are calculated with the harmonic balance method, while chaotic responses are integrated numerically. Chaotic time responses are inspected with the Fourier spectra, the Poincare´ projections, the maximum Lyapunov exponents and the principal component analysis. Chaotic responses are generated from the sub-harmonic resonance responses of 1/2 and 1/3 orders. The results of the principal component analysis shows that the lowest mode of vibration contributes to the chaotic response dominantly, while the second mode of vibration also contribute to the chaos with small amount of amplitude. Inspection of the kinetic energy of each vibration mode shows that the vibration mode with large axial displacement is also dominant in the chaotic response.
A Computational Product Model for Conceptual Design Using SysML
Authors: Wo¨lkl Stefan , Shea Kristina
Published: July 2010

The importance of the concept development phase in product development is contradictory to the level and amount of current computer-based support for it, especially with regards to mechanical design. Paper-based methods for conceptual design offer a far greater level of maturity and familiarity than current computational methods. Engineers usually work with software designed to address only a single stage of the concept design phase, such as requirements management tools. Integration with software covering other stages, e.g. functional modeling, is generally poor. Using the requirements for concept models outlined in the VDI 2221 guideline for systematic product development as a starting point, the authors propose an integrated product model constructed using the Systems Modeling Language (SysML) that moves beyond geometry to integrate all necessary aspects for conceptual design. These include requirements, functions and function structures, working principles and their structures as well as physical effects. In order to explore the applicability of SysML for mechanical design, a case study on the design of a passenger car’s luggage compartment cover is presented. The case study shows that many different SysML diagram types are suitable for formal modeling in mechanical concept design, though they were originally defined for software and control system development. It is then proposed that the creation and use of libraries defining generic as well as more complicated templates raises efficiency in modeling. The use of diagrams and their semantics for conceptual modeling make SysML a strong candidate for integrated product modeling of mechanical as well as mechatronic systems.
A Group Undo/Redo Mechanism to Preserve User Intention in Replicated Collaborative Modeling Systems
Authors: Huang Zhiyong , He Fazhi , Cai Xiantao , Li Xiaoxia , Cheng Yuan
Published: July 2010

Undo/redo mechanism is an important issue in interaction-centered CAD system. Since the design task is a creative process, the users of CAD systems have to use undo/redo mechanism to repeatly modify the CAD model in order to achieve a satisfied result. However, undo/redo mechanism is not an easy work even in standalone CAD systems. This is the reason why different commercial CAD systems are equipped with different level of undo/redo mechanism. Therefore, group undo/redo mechanism in collaborative system becomes a special challenge. This paper proposed a group undo/redo method in replicated collaborative modeling system. In our method, one user’s operation intention can be preserved in both local site and remote sites. The preservation is based on dependency relationship among users at different sites. The implementation of the Undo/Redo operation in both local site and remote site is described in detail respectively. The proposed approach has been tested in a prototype system with case study. The authors believe that this work represents the first attempt to address group undo/redo mechanism in collaborative CAD systems.
A New Method of Chaotic Anti-Control for Line Spectra Reduction of Vibration Isolation System
Authors: Zhang Zhenhai , Zhu Shijian , Liu Shuyong
Published: July 2010

Line spectra in the radiated noise of marine vessels are the most visible signs, which can be detected, tracked and identified by enemy’s passive sonar. Insertion of resilient isolators between the machinery and the base is one of the most common methods for controlling unwanted vibration of the hull of submarine. Isolators in service are usually assumed to be linear and almost all the vibration isolation-n systems (VIS) are designed with linear theory, which satisfies engineering requirements in most situations. However, the nonlinear dynamical characteristics of VIS have attracted increasing attention in recent years due to the facts that onboard machinery trends towards more powerful and lighter, and that the demands in engineering for reducing vibration become more rigorous. Furthermore, some distinguishing features of nonlinear systems can be applied to achieve some special functions, among which the most important one is using chaos to reduce line spectra in the radiated noise of submarines based on the fact that response spectrum of a nonlinear system under harmonic excitation is a continuous one when chaos occurs. In this paper, a chaos synthesis method based on tracking control is prososed for a vibration isolation system (VIS) of on board machinery to make the chaotic motion in nonlinear VIS persistent. In this way, the line spectra in the radiated noise can be reduced effectively because the response spectrum of a chaotic system under harmonic excitations is a continuous and reduced one. Numerical simulations were carried out and the results showed that utilizing this method the nonlinear VIS not only possesses an excellent isolation performance of vibration and line spectra, but also reduces the amplitude of the isolated equipment notably.
Elaboration and Investigation of the Acoustic Method of Elimination of Colorado Beetle
Authors: Sokol Galyna I. , Rybalka Tatyana A.
Published: July 2010

It is commonly known that vibrations and acoustic oscillations can cause both negative and positive influence on living organisms. The most harmful effect is caused by the tone acoustic oscillations when the tone frequency coincides with the resonance frequency of the whole body or individual organs. Hence, it is possible to make a conclusion that there are prerequisites for creation acoustic method having harmful or even mortal effect on the Colorado beetle organism. The subjects of the experiment were 8 beetles with the mass of 100 – 200mg. The frequency of the oscillation effect was 500–2500Hz. Examinations of the beetle after 6 hours showed that the biological death did take place. The repeated examination of the beetles after 24 hours showed the biological death of all the beetles exposed to acoustic influence. Using the described experiment, the resonance frequency for the beetle’s body was determined. So, it is possible to eliminate the Colorado beetle by exposing to vibration and acoustic oscillation. It is necessary to know the data relating to the mass of a beetle and its stiffness. Also, a question about the frequency band of the exposure arises. The resonance frequency of the body as a viscoelastic system is determined. The authors carry out experiments and determinate the mass and the stiffness of the Colorado beetle body. On the basis of the data of the outer inspection the biological death is registered for the beetle of the mass 100mg after the influence of the 1500Hz frequency vibration noise level was 120dB. On the basis of these data the stiffness of the Colorado beetle body is estimated as 8,860 N/m.
Piezoelectric Generators as Battery Chargers in Mobile Devices
Authors: Davis Matthew , Dubey Venketesh N. , Velay Xavier
Published: July 2010

This paper presents a design idea for an electric charging device designed to sit underneath the keypad of various mobile devices using piezoelectric and similar effect materials. It discusses the benefits of such a device and the current problems associated with developing one. The basis for the device is that multiple piezoelectric materials placed under the keypad are subjected to repeated loading from activities such as ‘texting’ or ‘menu browsing’. This causes a variable voltage generation which can assist in charging or other suitable function of the device. The paper shows the ways to achieve this goal and examine current piezoelectric generators.
A SEA Model for the Noise Analysis and Prediction of a Vacuum Cleaner
Authors: Yang Lifang , Long Zhiyong
Published: July 2010

As an effective method for middle and high-frequency vibro-acoustics prediction, SEA (Statistical Energy Analysis) has been successfully applied to some areas such as aerospace, ship, and car. In this paper, a statistical energy analysis model is built for studying the noise prediction and control of vacuum cleaner. First the principles for subsystem partition are provided and subsystems and connections of SEA model are completed in AutoSEA software. Then for complex structures, their equivalent parameters are discussed. For different structures, a series of formulae of SEA parameters are provided, such as module density, damping loss factor and coupling loss factor, the input power is obtained by experimental measurement. By comparing the simulated SPL(sound pressure level) with the measured SPL, the correctness of the model is verified. Furthermore, error sources of the model are analyzed. This study can offer guidance and reference on how to carry out noise-vibration study and build up vacuum cleaner SEA model.
A Real-Time Haptics-Based Deformable Model for Virtual Prototyping and Simulations
Authors: Wang Jinling , Lu Wen F.
Published: July 2010

Virtual reality technology plays an important role in the fields of product design, computer animation, medical simulation, cloth motion, and many others. Especially with the emergence of haptics technology, virtual simulation system provides an intuitive way of human and computer interaction, which allows user to feel and touch the virtual environment. For a real-time simulation system, a physically based deformable model including complex material properties with a high resolution is required. However, such deformable model hardly satisfies the update rate of interactive haptic rendering that exceeds 1 kHz. To tackle this challenge, a real-time volumetric model with haptic feedback is developed in this paper. This model, named as Adaptive S-chain model, extends the S-chain model and integrates the energy-based wave propagation method by the proposed adaptive re-mesh method to achieve realistic graphic and haptic deformation results. The implemented results show that the nonlinear, heterogeneous, anisotropic, shape retaining material properties and large range deformation are well modeled. An accurate force feedback is generated by the proposed Adaptive S-chain model in case study which is quite close to the experiment data.
Modeling of Dynamic Interaction Between Gun System Components During the Recoil Motion of the Gun
Authors: Ahmed Nadeem , Brown R. D. , Hetherington J. G.
Published: July 2010

The accuracy and consistency of a large caliber gun is largely dependent on its dynamic response during the firing cycle. A number of factors affecting the dynamic response of the gun include, the offset masses attached to the barrel, offset forces acting at a distance from the barrel axis and the dynamic interaction between the gun system components, including the shot-barrel interaction. Computer based modelling techniques can be used to model and simulate the motion of the gun during the firing cycle. These techniques are helpful in predicting the dynamic response of the gun system as well as the accuracy and consistency of the gun. A finite element computer modelling program ‘ANSYS’ was used to model a 120mm direct fire tank gun and simulate the dynamic response during the recoil motion. The contact algorithm in ‘ANSYS’ was used to simulate physical interaction between the gun system components. Simulations were also carried out in the Gun Dynamics program ‘SIMBAD’ by using the same gun system profile and the results obtained from both programs were compared. A case study is also presented to investigate the effect of gun design parameters on the dynamic response of the gun.
Formal Representation of Product Design Specifications for Validating Product Design
Authors: Weissman Alexander , Gupta Satyandra K. , Fiorentini Xenia , Sudarsan Rachuri , Sriram Ram
Published: July 2010

As collaborative efforts in electro-mechanical design have scaled to large, distributed groups working for years on a single product, an increasingly large gulf has developed between the original stated goals of the project and the final design solution. It has thus become necessary to validate the final design solution against a set of requirements to ensure that these goals have, in fact, been met. This process has become tedious for complex products with hundreds of design aspects and requirements. By formalizing the representation of requirements and the design solution, tools can be developed to a large extent automatically perform this validation. In this paper, we propose a formal approach for relating product requirements to the design solution. First, we present a formal model for representing product requirements. Then, we introduce the Core Product Model (CPM) and the Open Assembly Model (OAM) for representing the design solution. Finally, we link these models formally and provide an example with an actual consumer device.
Nonlinear Periodic Systems: Bands and Localization
Authors: Vakakis Alexander
Published: July 2010

We consider the dynamics of nonlinear mono-coupled periodic media. When coupling dominates over nonlinearity near-field standing waves and spatially extended traveling waves exist, inside stop and pass bands, respectively, of the nonlinear system. Nonlinear standing waves are analytically studied using a nonlinear normal mode formulation, whereas nonlinear traveling waves are analyzed by the method of multiple scales. When the nonlinear effects are of the same order with the coupling ones a completely different picture emerges, since nonlinear resonance interactions are unavoidable. As a result, infinite families of strongly and weakly localized nonlinear standing waves appear with frequencies lying in pass or stop bands of the corresponding linear periodic medium. Moreover, in the limit of weak coupling these solutions develop sensitive dependence on initial conditions, and the possibility of spatial chaos in the system exists. Some additional results on chaotic dynamics in linear periodic media with strongly nonlinear disorders are reviewed.
Periodic Steady State Response and Fatigue Analysis of a Nonlinear City Bus Model
Authors: Valsamos George , Theodosiou Christos , Natsiavas Sotirios
Published: July 2010

Dynamic response related to fatigue prediction of an urban bus is investigated. First, a quite complete model subjected to road excitation is employed in order to extract sufficiently reliable and accurate information in a fast way. The bus model is set up by applying the finite element method, resulting to an excessive number of degrees of freedom. In addition, the bus suspension units involve nonlinear characterstics. A step towards alleviating this difficulty is the application of an appropriate coordinate transformation, causing a drastic reduction in the dimension of the final set of the equations of motion. This allows the application of a systematic numerical methodology leading to direct determination of periodic steady state response of nonlinear models subjected to periodic excitation. Next, typical results were obtained for excitation resulting from selected urban road profiles. These profiles have either a known form or known statistical properties, expressed by an appropriate spatial power spectral density function. In all cases examined, the emphasis was put on investigating ride response. The main attention was focused on identifying areas of the bus suspension and frame subsystems where high stress levels are developed. This information is based on the idea of a nonlinear transfer function and provides the basis for applying suitable criteria in order to perform analyses leading to prediction of fatigue failure.
A Proposal of Wakuwaku Model of Interactive System Using Biological Signals
Authors: Ohkura Michiko , Hamano Masahide , Watanabe Hiroyuki , Aoto Tetsuro
Published: July 2010

To evaluate the Kansei of interactive systems, such subjective evaluation methods as questionnaire are usually used, even though they have some demerits. We objectively evaluate a system by quantifying its sensation of excitement using biological signals when one feels something interesting, because such signals can supplement the demerits of questionnaires. Thus, by focusing on excitement to derive a wakuwaku model, in this study we built various wakuwaku systems and evaluated them. Based on the biological signals measured during evaluation experiments, we derived a model using a neural network, and concluded that we can evaluate a system by the derived model.
Numerical Computation of Nonlinear Normal Modes in Multi-Mode Models of an Inertially Coupled Elastic Structure
Authors: Wang Fengxia , Bajaj Anil K.
Published: July 2010

There are many techniques available for the construction of nonlinear normal modes. Most studies for systems with more than one degree of freedom utilize asymptotic techniques or the method of multiple time scales, which are valid only for small amplitude motions. Previous works of the authors have investigated nonlinear normal modes in elastic structures with essential inertial nonlinearities, and considered two degree-of-freedom reduced-order models that exhibit 1:2 resonance. For small amplitude oscillations with low energy, this reduced analysis is acceptable, while for higher energy vibrations and vibrations that are away from internal resonances, this may not provide an accurate representation of NNMs. For high energy vibration and vibrations away from internal resonances, two natural issues to be addressed are the dimension of the reduced-order model used for constructing NNMs, and the order of nonlinearities retained in the truncated models. To address these issues, a comparison of NNMs computed for three different reduced degree of freedom models for the elastic structure is reported here. The reduced models considered are: (i) A two degree-of-freedom reduced model with only quadratic nonlinearities; (ii) A two degree-of-freedom reduced model with both quadratic and cubic nonlinearities; (iii) A five degrees-of-freedom model with both quadratic and cubic nonlinearities. A numerical method based on shooting technique is used for constructing the NNMs and results for system near 1:2 internal resonances between the two lowest modes and away from any internal resonance are compared.
Equation-Free Continuation of Maximal Vibration Amplitudes in a Nonlinear Rotor-Bearing Model of a Turbocharger
Authors: Elmegaard Michael , Ru¨bel Jan , Inagaki Mizuho , Kawamoto Atsushi , Starke Jens
Published: July 2010

Mechanical systems are typically described with finite element models resulting in high-dimensional dynamical systems. The high-dimensional space excludes the application of certain investigation methods like numerical continuation and bifurcation analysis to investigate the dynamical behaviour and its parameter dependence. Nevertheless, the dynamical behaviour usually lives on a low-dimensional manifold but typically no closed equations are available for the macroscopic quantities of interest. Therefore, an equation-free approach is suggested here to analyse and investigate the vibration behaviour of nonlinear rotating machinery. This allows then in the next step to optimize the rotor design specifications to reduce unbalance vibrations of a rotor-bearing system with nonlinear factors like the oil film dynamics. As an example we provide a simple model of a passenger car turbocharger where we investigate how the maximal vibration amplitude of the rotor depends on the viscosity of the oil used in the bearings.
Vibration of Planetary Gears With Elastically Deformable Ring Gears Parametrically Excited by Mesh Stiffness Fluctuations
Authors: Parker Robert G.
Published: July 2010

The parametric instability of planetary gears having elastic continuum ring gears is analytically investigated based on a hybrid continuous-discrete model. Mesh stiffness variations of the sun-planet and ring-planet meshes caused by the changing number of teeth in contact are the source of parametric instability. The natural frequencies of the time invariant system are either distinct or degenerate with multiplicity two, which indicates three types of combination instabilities: distinct-distinct, distinct-degenerate and degenerate-degenerate instabilities. By using the structured modal properties of planetary gears and the method of multiple scales, the instability boundaries are obtained as simple expressions in terms of mesh parameters. Instability existence rules for in-phase planet meshes are given. The instability boundaries are validated numerically.
Flow Pattern on the Surface of Airfoil With Lower Reynolds Number
Authors: Sun Xu , Zhang Jia-Zhong
Published: July 2010

In this paper, aerodynamic performance of the NACA0012 airfoil in the incompressible flow with a lower Reynolds number (Re) is investigated numerically from the viewpoints of flow pattern and nonlinear dynamics. First, the characteristic-based split (CBS) finite element method is introduced for the approximation of the incompressible Navier-Stokes equations, and then the lid-driven cavity flow and flow around a circular cylinder are calculated for varification. Then, at Re = 1000, flow fields around the NACA0012 airfoil at a series of angles of attack are simulated. With the increase of the attack angle, great change of the flow pattern appears, and the flow structures such as trailing edge vortex, separation bubble and shedding vortex are observed. Moreover, it is found that the separation bubble plays an important role in the deterioration of the flow stability at higher attack angles, and the vortex shedding can be taken as the result of a Hopf bifurcation while the bifurcation parameter is the angle of attack.
Information Generation in the Design Process
Authors: Mathieson James L. , Sen Chiradeep , Summers Joshua D.
Published: July 2010

This paper proposes and demonstrates a protocol for measuring information generated throughout a design process. The intent is to provide a consistent approach to allow the comparison of different design procedures and processes. The proposed method divides the design process into requirement, function, and component domains occurring within design iterations. To measure information or complexity in each of these domains, the elements describing the domains are counted and their mappings within and across the domains are computed. The results show that the proposed protocol and information metrics produce data points of comparable order across all domains under different design situations. Furthermore, it is shown that within-domain-coupling and across-domain-coupling metrics should be accommodate the continual increase in element count size without hiding relative changes in information generation throughout the process. When this correction is applied, it is observed that across-domain-coupling displays a decaying process of converging and diverging towards a steady state level. This presents possible support for the concepts of modeling the design process as a series of convergent and divergent processes while also suggesting that such oscillation may not be necessary.
Dynamics of Large Scale Finite Element Models With Multiple Unilateral Constraints
Authors: Theodosiou Christos , Iakovidis Anestis , Natsiavas Sotirios
Published: July 2010

Determination of the response of mechanical structures with complex geometry requires application of the finite element method. This leads frequently to models with a relatively large number of degrees of freedom, which may also possess nonlinear properties. Things become more complicated for systems involving unilateral contact and friction. In classical structural dynamics approaches, such constraints are usually modeled by special contact elements, with characteristics selected in a delicate manner. This study presents a systematic numerical methodology, which is suitable for determining dynamic response of large scale finite element models of mechanical systems involving multiple unilateral constraints. The method is based on a proper combination of results from two classes of direct integration methodologies. The first one includes standard methods employed in determining dynamic response of structural models with smooth nonlinearities, while the second class includes specialized methodologies that simulate response of dynamical systems with unilateral constraints. The validity and effectiveness of the methodology developed is illustrated by numerical results.
System Identification of Dynamic Systems With Cubic Nonlinearities Using Linear Time-Periodic Approximations
Authors: Allen Matthew S. , Sracic Michael W.
Published: July 2010

This work develops methods to identify parametric models of nonlinear dynamic systems from response measurements using tools for Linear Time Periodic (LTP) systems. The basic approach is to drive the system periodically in a stable limit cycle and then measure deviations of the response from that limit cycle. Under certain conditions, the resulting response can be well approximated as that of a linear-time periodic system. In the analytical realm it is common to linearize a system about a periodic trajectory and then use Floquet analysis to assess the stability of the limit cycle. This work is concerned with the inverse problem, using a measured time-periodic response to derive a nonlinear dynamic model for the system. Recently, a few new methods were developed that facilitate the experimental identification of linear time periodic systems, and those methods are exploited in this work. The proposed system identification methodology is evaluated by applying it to a Duffing oscillator, demonstrating that the nonlinear force-displacement relationship can be identified without a priori knowledge of its functional form. The proposed methods are also applied to simulated measurements from a cantilever beam with a cubic nonlinear spring on its tip, revealing that the model order of the system and the displacement dependent stiffness can be readily identified.
Application of the Energy Operator Separation Algorithm (EOSA) for the Instantaneous Amplitude and Frequency Calculation of Nonlinear Dynamic Systems Response
Authors: Gryllias Konstantinos , Antoniadis Ioannis
Published: July 2010

A number of non-linear dynamic responses require analysis with an increased resolution in their time domain representation, especially the ones presenting abrupt changes, such as those caused by the introduction of cracks, gaps, and slip. Typical technological applications include bearings or gears with localized defects. Since the time resolution of well-known time-frequency analysis tools (such as Wavelet-Transform) presents limitations, the Energy Operator Separation Algorithm (EOSA) is considered. The algorithm is based on the Teager-Kaiser nonlinear differential energy operator and leads to the calculation of the instantaneous amplitude and frequency of the response. Compared to the Hilbert transform, it leads at least to the same estimation errors, but in addition presents smaller computational complexity and faster adaptation, due to its instantaneous nature. The EOSA is applied on responses of a nonlinear Van der-Pol oscillator, on signals simulating the dynamic response of defective rolling element bearings and on three signals measured at industrial installations, resulting from defective bearings. In all cases the algorithm leads to the efficient calculation, mainly of the instantaneous amplitude of the signals. However, certain improvements are necessary in order to increase the smoothness, mainly of the resulting instantaneous frequency time waveforms.
Experimental Guidelines for NVH Improvements in Helicopter Vibro-Acoustic Comfort
Authors: Mucchi Emiliano , Pierro Elena , Vecchio Antonio
Published: July 2010

The noise of helicopters has started to become an important issue and the next level technical challenge is to include new design parameters such as vibro-acoustic comfort in the design process of a modern rotorcraft. In this scenario a wide experimental campaign has been performed on a EC-135 helicopter cabin in order to assess the effectiveness of several techniques for NVH (Noise Vibration and Harshness) improvements. Vibro-acoustical modal analyses of the cabin internal and external surface as well as a pure acoustical modal analysis of the cabin enclosure have been performed in order to verify the vibro-acoustical coupling between the cabin cavity and the cabin mechanical structure. Secondly a detailed leakage point detection on the cabin walls has been carried out by a few techniques finding out possible noise sources. Through such experimental analyses, some guidelines are suggested as well as particular techniques/instrumentations in order to improve human comfort on the helicopter cabin.
Topological Information Content and Expressiveness of Function Models in Mechanical Design
Authors: Sen Chiradeep , Caldwell Benjamin W. , Summers Joshua D. , Mocko Gregory M.
Published: July 2010

In this paper, two approaches for computing the topological information content of function models in mechanical engineering design are developed and compared. Previously a metric for computing information content of functions and flows within function models was proposed. Here this metric is adapted to compute the information contained in the resulting connections of flows between functions in a function model. The first approach is based on uniform unconditional probability of a flow connecting any two functions within the model. The second approach is based on additional knowledge that the functions and flows in a model have limited compatibility, thereby reducing the choices for origin and destination functions for each flow. This additional knowledge is represented using a new graphical representation supported by syntactical grammar rules. Both approaches are then applied to an example function model. Comparison between the approaches shows that the inclusion of compatibility knowledge increases the expressiveness of function representations and reduces the uncertainty of function models.
A CFD Study of Gas-Solid Flow in Cyclones With a Tangential Single Inlet and a Direct Asymmetrical Spiral Inlet
Authors: Xiong Bin , Amano R. S. , Lu Xiaofeng , Ji Yingfeng
Published: July 2010

This work presents a computational fluid dynamics (CFD) calculation of gas-solid flow in cyclones with a conventional tangential single inlet (CTSI) and a direct symmetrical spiral inlet (DSSI) which was developed by Zhao et al [1]. The Reynolds stress model (RSM) has been employed to predict the gas flow field and particle paths are calculated with the stochastic Lagrangian model. The calculated grade collection efficiency and pressure drop have reasonable agreement with the experimental data. All results indicate that the DSSI has effect on significantly increasing collection efficiency with insignificantly increasing pressure drop. Compared with the CTSI cyclone, the DSSI cyclone has higher collection efficiency due to larger tangential velocity distribution, less short re-circuiting flow and shorter distance for particles to move to the wall. But the larger tangential velocity distribution lead to a little higher pressure drop of the cyclone with DSSI.
Efficient Impulse Momentum Formulation for Multi-Flexible Body Systems
Authors: Mukherjee Rudranarayan M. , Anderson Kurt S.
Published: July 2010

This paper presents the generalization of the divide and conquer impulse momentum formulation to systems with flexible bodies. The approach utilizes a hierarchic assembly-disassembly process by traversing the system topology in a binary tree map to solve for the jumps in the system generalized speeds and the constraint impulsive loads in linear and logarithmic cost in serial and parallel implementations, respectively. The coupling between the unilateral and bilateral constraints is handled efficiently through the use of kinematic joint definitions. The equations of motion for the system are produced in a hierarchic sub-structured form. The generalized impulse momenta equations of flexible bodies are derived using a projection method. The equations are then cast into a format amenable to be incorporated in the basic divide and conquer form. The solution of the equations using the hierarchic assembly disassembly process by using the boundary conditions are discussed for free floating, anchored trees and kinematically closed loop systems.
Modal Sensitivities, Spatial Signal Distribution and Average of Segmented Ring Sensors
Authors: Lin Y. S. , Chang C. C. , Chu C. C. , Tzou H. S.
Published: July 2010

Distributed monitoring is essential to effective actuation and vibration control of shell-type precision structures. In this paper, electro-mechanics and sensitivities of distributed segmented piezoelectric shell sensors applied to ring shells are evaluated. Since sensor signals are modal dependent, natural modal characteristics, emphasizing the circumferential modes, are studied first. Then, with the segmentation technique, distributed segmented sensors with various lengths are designed and their signal generations resulting from modal strains are evaluated. The total output signals includes four components: 1) a bending strain induced signal by the circumferential oscillatory amplitude, 2) a bending strain induced signal by the transverse oscillatory amplitude, 3) a membrane strain induced signal by the circumferential oscillatory amplitude and 4) a membrane strain induced signal by the transverse oscillatory amplitude respectively at the transverse and circumferential modal component frequencies. Furthermore, the sensor sensitivities are divided into: 1) the transverse modal sensitivity and 2) the circumferential modal sensitivity. Parametric studies (e.g., ring radius, sensor thickness, ring thickness and sensor segment length) are conducted to evaluate the spatial signal distributions and component signal generations of segmented ring sensors. All data indicate that ring’s circumferential, not transverse, component mode dominates the total signal generation.
Vibration Analysis of Composite Beams With End Effects via the Formal Asymptotic Method
Authors: Kim Jun-Sik , Wang K. W.
Published: July 2010

Free vibration analysis of composite beams is carried out by using a finite element-based formal asymptotic expansion method. The formulation begins with three-dimensional equilibrium equations in which cross-sectional coordinates are scaled by the characteristic length of the beam. Microscopic 2D and macroscopic 1D equations obtained via the asymptotic expansion method are discretized by applying a conventional finite element method. Boundary conditions associated with macroscopic 1D equations are also considered in order to investigate the end effect. We then describe how to form and solve the eigenvalue problems derived from the asymptotic method beyond the classical approximation. The results obtained are compared to those of 3D FEM and those available in literature for composite beams with solid cross-section and thin-walled cross-section.
An Experimental Investigation of Acoustic Band Gaps and Localization in Granular Elastic Chains
Authors: Boechler Nicholas , Daraio Chiara
Published: July 2010

We assembled a chain composed of a periodic arrangement of aluminum and steel spheres encased in a 4-rod polycarbonate holder with tunable static precompression applied by means of a lever actuated system. To excite periodic oscillations we perturbed the chain with a piezo-stack actuator driven by both continuous and finite bursts of a sinusoidally varying periodic signal. The amplitude of the periodic signal ranged from linear to strongly nonlinear regimes. We report the tunability of the frequency range for the band gap edges as a function of the material parameters, chain geometry and stress conditioning. We analyze the data by means of force-time plot and Fast Fourier Transforms (FFT). We observe a dramatic reduction of the transmitted wave amplitude for harmonic excitations with fundamental frequencies within the gap. The application of both continuous and short bursts of perturbation allows for observation of different dynamic phenomena at selected frequency ranges (in particular close to the lower optical branch edge). By varying the amplitude of the dynamic excitation (and therefore the level of the nonlinearity present in the system) we seek localized discrete breathing modes and surface instabilities. The comparison between continuum theory, discrete numerical modeling and experiments show a qualitative agreement and provide fundamental understanding for future investigation and numerous engineering applications. The challenges and considerations involved with the construction of an experimental system capable of capturing and leveraging on the described phenomena will be detailed.
Non Linear Dynamic Behaviour Modelling of a Planar Friction Interface in a Structure Assembly
Authors: Peyret N. , Dion J.-L. , Chevallier G. , Argoul P.
Published: July 2010

This paper deals with the energy losses caused by micro-slip in a planar interface of a structure. Taking into account friction in the joints during the analysis of dynamic systems remains difficult. This paper proposes an analytical study of flexural vibrations of a clamped-clamped beam, the novelty of this experiment is that the position of the interfaces has never been tested before to our knowledge. First, the authors described the benchmark and justified the choice of the position of the interfaces. The second section presents the displacement and stress fields during each phase of the loading process in the joints under the assumption of quasi static motion. In the third part, the authors calculated the energy dissipated by friction in the interface on a loading cycle. This leads to a definition of the energy dissipated by friction in the interface and thus to a non linear loss factor. This loss factor is then optimized according to the height of the beam. In the last part of the paper, the dynamic response of the beam is calculated using this non linear loss factor.
Mobile Agents and Related Features for Real Time First Responder Training Systems
Authors: Honda Jason , Cheng Harry H. , Djordjevich Donna D.
Published: July 2010

This article discusses how mobile agents and scripting technology can play an important role in first-responder training simulations. From a training perspective, the power of mobile agents can greatly improve the training experience if they are easy to use and integrate and have the necessary power. Certain features should be available to mobile agents in applications such as this. As opposed to traditional mobile agent applications, supplementing a real-time training system with a mobile agent system requires many features so that agents integrate appropriately with the running application. Mobile agents with the ability to interface with the running binary application and with the features discussed in this paper can be very effective and valuable. This paper looks at the features that are necessary. We implement these features into a mobile agent system, Mobile-FIRST, and then examine its use in a first responder training video game currently in production. Using a system with these principles, integration of mobile agents becomes simple and intuitive, and can greatly improve the application in many different ways.
Applying TRIZ to Support Designers in a Descriptive Design Framework
Authors: Pham Duc Truong , Ng Kok Weng , Ang Mei Choo
Published: July 2010

Designing a new product can be a challenging task particularly for a novice designer. This paper explores the application of TRIZ to assist a designer in performing this task within a descriptive design framework. The descriptive design framework permits the designer to track his ideas throughout the design process. The ‘technical contradiction matrix’ of TRIZ is integrated into this framework to allow it to provide support to designers. This contradiction matrix is adapted to enable designers to assign their levels of belief or preference to contradicting features to solve design problems. This preference assignment allows more emphasis to be placed on the critical features of a design problem. The proposed TRIZ-based system was tried out on a novice designer in a case study to design a scheme to support concrete filling between beams.
A Substructure Based Reduced Order Model for Mistuned Bladed Disks
Authors: Hohl Andreas , Siewert Christian , Panning Lars , Wallaschek Jo¨rg
Published: July 2010

A efficient method for the calculation of the forced response of mistuned bladed disks is introduced. Based on the Component Mode Synthesis techniques the structure is divided into substructures, namely the disk and the blades. The Component Mode Synthesis of the disk is calculated with a fast and accurate cyclic symmetry approach. A recently developed method called Wave Based Substructuring is used to describe the (numerous) coupling degrees of freedom between the disk and the blades. The orthogonal waves are derived with a Singular Value Decomposition or a QR decomposition from the coupling nodes’ normal modes calculated by a modal analysis of the full structure.
A Fractional Order Signal Processing (FOSP) Technique for Chemotaxis Quantification Using Video Microscopy
Authors: Sheng Hu , Sun Hongguang , Chen YangQuan , Mounteer Leslie C. , Kmetzsch Victoria G. , Miller Charles D. , Zhou Anhong
Published: July 2010

Bacterial chemotaxis has recently attracted great interest in purification of groundwater, monitored natural attenuation and contaminant containment. Quantitatively evaluating chemotaxis accurately would lead to a better comprehension of the role of chemotaxis and its broad use in applications. Many mathematical, statistical or experimental quantitative parameters have been reported to quantify the chemotaxis, but how to accurately quantify chemotaxis is still uncertain. In this paper, a new quantification method based on fractional order signal processing (FOSP) is developed. According to the detailed analysis of chemotaxis model, the complex Hurst value H and complex α-stable parameter was developed to quantify chemotaxis for the first time. The Hurst parameter Hθ and α value αθ of instantaneous direction θ(t) are provided to characterize the bacteria migration more comprehensively. The new quantification parameters provide a reliable and comprehensive assessment of the migration of bacteria.
A Stochastic Approach to Integrated Vehicle Reliability Prediction
Authors: Madsen Justin , Ghiocel Dan , Gorsich David , Lamb David , Negrut Dan
Published: July 2010

This paper addresses some aspects of an on-going multiyear research project of GP Technologies in collaboration with University of Wisconsin-Madison for US Army TARDEC. The focus of this research project is to enhance the overall vehicle reliability prediction process. A combination of stochastic models for both the vehicle and operational environment are utilized to determine the range of the system dynamic response. These dynamic results are used as inputs into a finite element analysis of stresses on subsystem components. Finally, resulting stresses are used for damage modeling and life and reliability predictions. This paper describes few selected aspects of the new integrated ground vehicle reliability prediction approach. The integrated approach combines the computational stochastic mechanics predictions with available statistical experimental databases for assessing vehicle system reliability. Such an integrated reliability prediction approach represents an essential part of an intelligent virtual prototyping environment for ground vehicle design and testing.
Estimation of States and Parameters in Chaotic Systems Using Particle Swarm Optimization
Authors: Samanta B. , Nataraj C.
Published: July 2010

A study is presented on the application of particle swarm optimization (PSO) for estimation of states and parameters in chaotic systems. The parameter estimation is formulated as a nonlinear optimization problem using PSO to minimize the synchronization error for the observable states of the actual system and its mathematical model. The procedure is illustrated using a typical chaotic system of Lorenz equations. Results are presented to study the effects of different observable system states and observation noise on parameter estimation. The effectiveness of different variants of PSO on parameter estimation is also studied. The results show the capability of the proposed PSO based approach in estimating the chaotic system parameters with wide search range (50–200%) and in the presence of observation noise.
Path Tracking Design by Fractional Prefilter Extension to Square MIMO Systems
Authors: Melchior P. , Inarn C. , Oustaloup A.
Published: July 2010

The aim of this paper concerns motion control and robust path tracking. An approach based on fractional prefilter synthesis was already developed. It allows tracking optimization according to the fractional derivation order, the actuators physical constraints and the control loop frequency bandwidth. The purpose of this paper is the extension of this approach to multivariable systems. A non integer prefilter synthesis methodology for square MIMO systems (Multi-Input, Multi-Output) is presented. It is based on the MIMO-QFT robust synthesis methodology, taking into account of the plant uncertainties. MIMO-QFT robust synthesis methodology is based on multiple SISO (MISO systems) synthesis by considering the loop couplings. The SISO-QFT synthesis methodology can be then used for each SISO synthesis. Then the prefilters are synthesized. The prefilter parameter optimization is founded on the prefilter output error integral minimization, taking into account of the actuators physical constraints and the tracking performance specifications. An application example is given.