WSEAS Transactions on Applied and Theoretical Mechanics
Print ISSN: 1991-8747
Volume 10, 2015
Notice: As of 2014 and for the forthcoming years, the publication frequency/periodicity of WSEAS Journals is adapted to the 'continuously updated' model. What this means is that instead of being separated into issues, new papers will be added on a continuous basis, allowing a more regular flow and shorter publication times. The papers will appear in reverse order, therefore the most recent one will be on top.
Volume 10, 2015
Title of the Paper: Phenomenological Analysis of the Additive Combinational Internal Resonance in Nonlinear Vibrations of Fractionally Damped Thin Plates
Authors: Y. A. Rossikhin, M. V. Shitikova, J. C. Ngenzi
Abstract: The dynamic behaviour of a nonlinear plate embedded into a fractional derivative viscoelastic medium is studied by the method of multiple time scales under the conditions of the combinational internal resonances of additive-difference type using a newly developed approach resulting in uncoupling the linear parts of equations of motion of the plate. The influence of viscosity on the energy exchange mechanism between interacting nonlinear modes has been analyzed. The phenomenological analysis carried out for the combinational internal resonances of the additive type with the help of the phase portraits constructed for different magnitudes of the plate parameters reveals the great variety of vibrational motions: stationary vibrations, two-sided energy exchange between two subsystems under consideration, and one-sided energy interchange resulting in the complete one-sided energy transfer.
Keywords: Nonlinear elastic plate, Free nonlinear damped vibrations, Combinational internal resonances, Fractional derivative, Method of multiple time scales
WSEAS Transactions on Applied and Theoretical Mechanics, ISSN / E-ISSN: 1991-8747 / 2224-3429, Volume 10, 2015, Art. #30, pp. 260-277
Title of the Paper: Measuring and Evaluation of the Shape and Size of Initial Geometrical Imperfections of Structural Glass Members
Authors: Ondřej Pešek, Jindřich Melcher
Abstract: Buckling resistance (including flexural buckling and lateral-torsional buckling) is major design parameter for many structural glass components. Buckling resistance is influenced by several parameters: boundary conditions, slenderness and initial imperfections. Initial imperfections, in particular initial geometrical out-of plane curvatures are very poorly presented in literature. In this paper measuring and determining of initial geometrical imperfections of fifteen specimens are presented. Measured specimens had the same dimensions but they had different composition – there are made from monolithic glass or laminated glass using PVB or EVA foil bonding together annealed glass panes or fully tempered glass panes. The shape of initial overall bow was measured using CARL ZEISS testing equipment. Information about initial curvature shapes and amplitudes are major conclusions resulting from statistical evaluation of tests.
Keywords: Structural glass, initial geometrical imperfections, flexural buckling, normal distribution, lognormal distribution
WSEAS Transactions on Applied and Theoretical Mechanics, ISSN / E-ISSN: 1991-8747 / 2224-3429, Volume 10, 2015, Art. #29, pp. 253-259
Title of the Paper: The Simulation of Wraparound Fins’ Aerodynamic Characteristics
Authors: Minjiao Li, Laith K. Abbas, Xiaoting Rui
Abstract: To study the aerodynamic characteristics of the wraparound fins, the TTCP standard wraparound fins (WAF) model was simulated using the computational fluid dynamics (CFD) method based on the shear transport (SST) k-? turbulent model. First, the grid independence verification was considered by using three mesh systems of different densities to calculate the model’s aerodynamic coefficients. The maximum difference is within 2%. Then, the aerodynamic coefficients of the wing-wrapped vehicle model at different Mach numbers were calculated. The simulated results were compared with the experimental data, and the error could be acceptable. Finally, the WAF model’s aerodynamic characteristics as a function of Mach number and angle of attack are analyzed.
Keywords: Wraparound Fins, CFD, Simulation, Aerodynamic Characteristics
WSEAS Transactions on Applied and Theoretical Mechanics, ISSN / E-ISSN: 1991-8747 / 2224-3429, Volume 10, 2015, Art. #28, pp. 247-252
Title of the Paper: Spatial and Temporal Instability of Shallow Mixing Layers in the Presence of Non-Constant Resistance Force
Authors: Ilmars Iltins, Marija Iltina, Valentina Koliskina, Andrei Kolyshkin, Inta Volodko
Abstract: Two methods for linear stability analysis of shallow mixing layers are presented in the paper: temporal stability analysis and spatial stability analysis. The combined effect of small curvature and nonconstant friction force in the transverse direction is analyzed. Both spatial and temporal linear stability problems are solved numerically by means of a collocation method based on Chebyshev polynomials. Marginal stability curves are obtained for different values of the parameters of the problem. It is shown that both curvature and variable friction stabilize the flow.
Keywords: Linear stability analysis, small curvature, non-uniform friction, shallow mixing layer
WSEAS Transactions on Applied and Theoretical Mechanics, ISSN / E-ISSN: 1991-8747 / 2224-3429, Volume 10, 2015, Art. #27, pp. 241-246
Title of the Paper: Application of Digital Speckle Correlation Method (DSCM) with 4 Nodes or 8 Nodes in the Wood Fracture Mechanics
Authors: Xiaomao Zhao, Ping Yang, Dong Zhao
Abstract: This article proposes a digital speckle correlation method (DSCM) displacement type based on finite element (FE) algorithm, in order to be suited for the irregular deformation and improve the precision of the DSCM. Both simulation and experiment processing, including three point bending deformation, show that the proposed method can achieve nearly the same accuracy as the finite element method in most cases and higher accuracy.
Keywords: Digital speckle correlation method, Finite element, Displacement type
WSEAS Transactions on Applied and Theoretical Mechanics, ISSN / E-ISSN: 1991-8747 / 2224-3429, Volume 10, 2015, Art. #26, pp. 235-240
Title of the Paper: Investigating Effect on Contact Stiffness on the Low Velocity Impact Response of Curved Composite Plate
Authors: Buddhi Arahchige, Hessam Ghasemnejad, Andre Agousti
Abstract: The low velocity impact response of a curved stiffness composite panel is studied. A two degree of freedom spring-mass model is used to evaluate the contact force between the composite panel and the impactor. This work uses the Hertzian contact model which is linearized for the impact analysis of the curved composite panel. First order shear deformation theory coupled with Fourier series is used to derive the governing equations of the curved composite panel. In this paper, the effect of contact stiffness on the impact force is studied analytically. The results showed that the impact force increased with increase of contact stiffness.
Keywords: FSDT, CPT, Hertzian, MATLAB, stiffness matrix
WSEAS Transactions on Applied and Theoretical Mechanics, ISSN / E-ISSN: 1991-8747 / 2224-3429, Volume 10, 2015, Art. #25, pp. 227-234
Title of the Paper: Evaluation of Noise Level Inside Cab of a Bi-Fuel Passenger Vehicle
Authors: D. Siano, M. V. Prati, M. A. Costagliola, M. A. Panza
Abstract: It is well known that the vehicle interior noise comfort is one of the main target which may attract customers for purchasing a vehicle. Eventually, the amount of discomfort depends on magnitude, frequency, direction and, as well as, on the duration in vibration exposition inside the cabin. The comfort of the driving strongly influences the driving performances. Generally, the acoustic noise exposition depends on two main sources: engine and powertrain systems and interaction between tyre and road surface. In this paper, the sound quality assessment of a bi-fuel passenger car tested over a chassis-dynamometer bench at different vehicle operating conditions, will be analyzed. The main target of the study is to measure the perceived noise inside cabin for different vehicle speed conditions assessing the influence of the investigated operating conditions on the driver’s acoustic comfort.
Keywords: Acoustic Cavity, Interior Noise, Loudness, Sharpness, Sound Quality, Vehicle
WSEAS Transactions on Applied and Theoretical Mechanics, ISSN / E-ISSN: 1991-8747 / 2224-3429, Volume 10, 2015, Art. #24, pp. 220-226
Title of the Paper: Finite Element Implementation of a Novel Version of Strain Gradient Elasticity
Authors: M. Lederer, G. Khatibi
Abstract: A novel version of strain gradient elasticity is proposed. This theory emerges from an older version of strain gradient elasticity suggested by Toupin and Mindlin through replacement of their asymmetric stress by a symmetric stress tensor. In this way one derives an improvement of the theory which is mathematically sound. Since analytical solutions are not easy to achieve within this approach, a numerical solution is elaborated with use of Finite Element Analysis. Thus, the theory is implemented in the commercial FEM software ABAQUS through user subroutine UEL. It is demonstrated for the example of a shear test that the stress singularities occurring in classical continuum theory have now disappeared.
Keywords: Finite Element Analysis, Strain Gradient Elasticity, shear test, singularity removal
WSEAS Transactions on Applied and Theoretical Mechanics, ISSN / E-ISSN: 1991-8747 / 2224-3429, Volume 10, 2015, Art. #23, pp. 213-219
Title of the Paper: Twin Boundary Migration and Nanocrack Generation in Ultrafine-Grained Materials with Nanotwinned Structure
Authors: Ilya Ovid’ko, Alexander Sheinerman, Nikolay Skiba, Stanislav Krasnitiskiy, Andrei Smirnov
Abstract: A theoretical model is suggested which describes plastic flow and crack generation through twin boundary migration in nanotwinned metals (ultrafine-grained metallic materials containing high-density ensembles of nanoscale twins within grains). Within the suggested model, migration of twin boundaries under a mechanical load carries plastic deformation and leads to formation of wedge disclinations at the junctions of twin and grain boundaries. These disclinations create high local stresses that produce strengthening of nanotwinned metals and can induce nanocrack generation. Within the model, we calculate the flow stress as a function of twin thickness in nanotwinned metals in the situation where twin boundary migration significantly contributes to plastic flow. We also consider generation of nanocracks in nanotwinned metals during migration of twin boundaries and calculate the conditions for crack formation. Besides, our theoretical results and their comparison with corresponding experimental data are briefly discussed.
Keywords: Nanotwinned materials, plastic deformation, yield strength, fracture, cracks, defects, modeling
WSEAS Transactions on Applied and Theoretical Mechanics, ISSN / E-ISSN: 1991-8747 / 2224-3429, Volume 10, 2015, Art. #22, pp. 204-212
Title of the Paper: Numerical Simulation of Shot Peening Process: Influence of the Constitutive Model of the Target Material
Authors: Peñuelas I., Rodríguez C., García T. E., Belzunce F. J.
Abstract: This paper analyse the effect of the constitutive material model used to describe the target material on the results obtained from numerical simulation of shot peening process. From experimental characterization of a duplex stainless steel, including both high rate monotonic tests and low cyclic fatigue tests, three constitutive models are proposed and incorporated into a FE simulation. Numerical predictions of residual stresses and roughness, and experimental results are compared. Best results were obtained using a non-linear kinematic–isotropic model which combines the effect of the cyclic deformation produced by repeated impacts with the strain rate effect through its isotropic component. The only consideration of the effect of the strain rate, overestimate the experimental values of residual stress. On the other hand, if only the cyclic loading effect is taken into account, numerical predictions underestimate the actual residual stresses values.
Keywords: Shot peening, Duplex stainless steel, Constitutive model, Numerical simulation
WSEAS Transactions on Applied and Theoretical Mechanics, ISSN / E-ISSN: 1991-8747 / 2224-3429, Volume 10, 2015, Art. #21, pp. 194-203
Title of the Paper: Quadrilateral Quantum Chain Hamiltonian Cast in Positive Semidefinite Form Containing Non-Linear Fermionic Contributions
Authors: Gyorgy Kovacs, Konstantin Glukhov, Zsolt Gulacsi
Abstract: The transformation of a Hamiltonian (connected to a quantum mechanical many-body system) in positive semidefinite form represents an important procedure in a powerful tool used in deducing exact results for nonintegrable systems. Motivated by this fact, we report in this paper the exact transformation of a Hubbard type of Hamiltonian (describing in the presented case an itinerant fermionic quadrilateral chain) in positive semidefinite form, in a such a way that the kinetic and interaction energy terms of the Hamiltonian are treated similarly together, and are provided by the same positive semidefinite expression. For this reason, non-linear fermionic contributions are used in block operators from which the positive semidefinite forms are constructed. The transformation is possible to be done when a system of nonlinear equations, called matching equations, are satisfied. The procedure of solving the matching equations is also indicated.
Keywords: Non-integrable many-body systems, Hamiltonian in positive semidefinite form, exact ground states
WSEAS Transactions on Applied and Theoretical Mechanics, ISSN / E-ISSN: 1991-8747 / 2224-3429, Volume 10, 2015, Art. #20, pp. 187-193
Title of the Paper: Investigation on Thermal Stress-Strain State in Multilayered Composites during Nickel Aluminide Coatings Formation
Authors: Victor Shmorgun, Artem Bogdanov, Mikhail Trunov, Alexandr Taube
Abstract: In this study multi-layered steel-nickel-aluminum composite with intermetallic interlayers was obtained using complex process which included explosion welding and heat treatment. Strength properties of the diffusion NiAl3+Ni2Al3 interlayer under thermal stress were investigated. The thickness value of diffusion interlayer as well as thickness ratios of composites components contributing to the rupture of the intermetallic interlayer during thermal loading were identified via standard method and verified using FEM simulation. The calculated results correspond with the experimental investigations. The interlayer rupture resulted in the formation of Ni/Ni2Al3 coating on steel.
Keywords: Laminated composites, steel, aluminum, coating, explosion welding, nickel aluminide
WSEAS Transactions on Applied and Theoretical Mechanics, ISSN / E-ISSN: 1991-8747 / 2224-3429, Volume 10, 2015, Art. #19, pp. 180-186
Title of the Paper: Power Consumption of Electromagnetic Valvetrain System
Authors: Liang Liu, Siqin Chang
Abstract: The electromagnetic valvetrain (EMVT) has been widely investigated and considered to have great capability to improve the fuel economy, the emissions, and the torque output performance of the engine. While the mechanical camshaft driven valvetrain consumes mechanical energy to drive the valves, the EMVT consumes electrical energy. If the power consumption is not properly controlled, the improvement of engine fuel economy brought by camless valvetrain will be weakened. This paper focus on the power consumption of EMVT. The detailed power losses derivation of the EMVT was discussed and compared with conventional valvetrain. The power consumption and pumping losses at various valve operating modes are shown and compared, including various engine speed, variable transition time, variable valve lift, and valve deactivation. The result shows that the power consumption is almost proportional to the engine speed. At low engine speeds and low engine loads, the power consumption can be reduced by applying long transition time and small valve lift. The power consumption can also be reduced by deactivating half of the intake valves at low engine loads.
Keywords: Camless, Electromagnetic valvetrain, Power consumption, Variable valve, Pumping loss
WSEAS Transactions on Applied and Theoretical Mechanics, ISSN / E-ISSN: 1991-8747 / 2224-3429, Volume 10, 2015, Art. #18, pp. 174-179
Title of the Paper: Method of Static Determination of the Safety Against Overturning of the Road – Rail Machines
Authors: Ioan Sebeşan, Marius-Ovidiu Ene
Abstract: In the present work, it is shown an overturning safety statically procedure for a road – rail machine, with a dual road and rail rolling system. It is analyses the rail rolling variant of the machine, when it will be deemed as an railway motor vehicle
Keywords: Road-rail machine, overturning, wheel load, super-elevation
WSEAS Transactions on Applied and Theoretical Mechanics, ISSN / E-ISSN: 1991-8747 / 2224-3429, Volume 10, 2015, Art. #17, pp. 169-173
Title of the Paper: Analysis of Multi-Body Nonlinear Dynamic Modeling and Motion Characteristics of Flexible-Wing Aircraft
Authors: Hao Zhang, Zi-li Chen, Jingang Qiu
Abstract: Flexible-wing aircraft has more applications than traditional parafoil system for its superior flight performance and height controllability. In consideration of the apparent mass of parafoil and the relative motion between two bodies, an eight degrees of freedom (DOF) nonlinear dynamic model is proposed against the special structure of two-point flexible connection of the flexible-wing aircraft, including six DOF of parafoil and two relative motion DOF of payload. The simulation emphasizes on the analysis of the model’s relative motion of turning, flare landing and responses to thrust and wind disturbances. The result shows the flexible-wing aircraft is subjective to wind disturbance and the control may cause varying degrees of relative motion between two bodies, thereby further verifying model correctness and applicability.
Keywords: Flexible-wing aircraft, Multi-body, Nonlinear dynamic, Relative motion, Wind disturbances
WSEAS Transactions on Applied and Theoretical Mechanics, ISSN / E-ISSN: 1991-8747 / 2224-3429, Volume 10, 2015, Art. #16, pp. 154-168
Title of the Paper: Chart of Solutions of the Two Degrees of Freedom - Dynamical System of the Coupled Non-Linear Double Oscillator for Various Sets of Parameter Values of its Potential
Authors: Maria A. Leftaki, Evangelos P. Valaris
Abstract: This paper presents the approximate general solution of the axi-symmetric, two-degree of freedom dynamical system of the coupled non-linear double oscillator corresponding to a third order polynomial potential. The general solution is approximated through a set of initial conditions that generate symmetric periodic solutions and a set of initial conditions that generate escape solutions. We give the chart of initial conditions of solutions for various sets of parameter values A and B representing the coefficients of the second degree terms in x and y, respectively, appearing in the polynomial potential, while we retain constant, e.g. b=0.5, the coefficient of the third degree term x y2.
Keywords: Non-linear double oscillator, escape solutions, third order potential, periodic symmetric solutions
WSEAS Transactions on Applied and Theoretical Mechanics, ISSN / E-ISSN: 1991-8747 / 2224-3429, Volume 10, 2015, Art. #15, pp. 148-153
Title of the Paper: Mechanism-Hydraulic Co-Simulation Research on the Test Bed of Gun Recoil Mechanism
Authors: Yuliang Yang, Changchun Di, Junqi Qin, Yanfeng Yang
Abstract: In the test bed of recoil mechanism, recoil mechanism completed the recoil and counterrecoil process, pushed by hydraulic cylinder. The test bed consisted of the mechanical system, the hydraulic system and the electrical system. Based on ADAMS software and EASY5 software, the dynamic model and hydraulic system model of test bed were respectively built. On the basis of these models, mechanism-hydraulic co-simulation model of test bed was built, and co-simulation analysis was developed. The movement curves of piston rod and pressure curves of accumulators were obtained. The study will provide a theoretical basis for the engineering application of test bed.
Keywords: recoil mechanism, test bed, dynamic model, plug-in valve, hydraulic system model, co-simulation
WSEAS Transactions on Applied and Theoretical Mechanics, ISSN / E-ISSN: 1991-8747 / 2224-3429, Volume 10, 2015, Art. #14, pp. 142-147
Title of the Paper: Generalization of PER Model for the Whole Liner Height Analysis of Asymmetric Shaped Charges
Authors: Mohammad Javad Tabatabaie Fakhar, Mohammad Hossein Abolbashari
Abstract: This paper presents a model that explains the liner collapse phenomenon for the whole liner height analysis of conical shaped charges in presence of geometrical asymmetries. In presence of geometrical asymmetries, the velocities of the elements lying on the two arms of the liner may not be symmetric. Therefore, the elements colliding at the core will have different distances from the nominal axis of symmetry, and of course will not meet on the axis. Some solution methods which are applicable to asymmetric models, converge for conditions such as incomplete traversing of the wave front over the liner, and therefore are not applicable for general description of jet and slug formation. With those methods the detonation wave can traverse 72% to 90% of the liner height for a typical shaped charge. In fact, because of ill-conditioning and/or numerical errors, convergence is not guaranteed with other solution methods near the end positions of the liner (near the base). In the proposed model, a generalized form of classical jet formation theory and its proper solution method is developed for analysis of the whole liner in asymmetric conditions. The present method can solve the generalized form of the PER model to 100% of the liner height. Thus the determination of the asymmetry effects of the whole liner height is easily possible. In other words, in the present paper a different method has been proposed that determines the core coordinate and its motion for the whole liner height. In the present model, the specifications of the jet and slug, such as off-axis jet velocity is validated with previous works.
Keywords: Asymmetric shaped charge, Jet, Slug, Liner, Detonation, Collapse phenomenon
WSEAS Transactions on Applied and Theoretical Mechanics, ISSN / E-ISSN: 1991-8747 / 2224-3429, Volume 10, 2015, Art. #13, pp. 135-141
Title of the Paper: The Impact Induced 3:1 Internal Resonance in Nonlinear Doubly Curved Shallow Panels with Rectangular Platform
Authors: Y. A. Rossikhin, M. V. Shitikova, Muhammed Salih Khalid J. M.
Abstract: Geometrically non-linear vibrations of doubly curved shallow panels with rectangular platform under the low-velocity impact by an elastic sphere are investigated. It is assumed that the target is simply supported and partial differential equations are obtained in terms of its transverse displacement and Airy’s stress function. The local bearing of the target and impactor’s materials is neglected with respect to the shell deflection in the contact region. The equations of motion are reduced to a set of infinite nonlinear ordinary differential equations of the second order in time and with cubic and quadratic nonlinearities in terms of the generalized displacements. The internal resonance three-to-one induced during the process of impact is investigated by the method of multiple time scales. The time dependence of the contact force is determined.
Keywords: Doubly curved shallow panel rectangular in base, Method of multiple time scales, Impact induced resonance, Internal resonance three-to-one
WSEAS Transactions on Applied and Theoretical Mechanics, ISSN / E-ISSN: 1991-8747 / 2224-3429, Volume 10, 2015, Art. #12, pp. 117-134
Title of the Paper: Bifurcations in the Dynamic System of the Mechanic Processing in Metal-Cutting Tools
Authors: Vilor Zakovorotny
Abstract: The nonlinear dynamics in processing of metal-cutting tools is considered. The author proposes the mathematical model that includes two spatial elastic subsystems. They interact through the dynamic connection, which is a force in the model of coordinates of the system state. The simultaneous excitation sources and nonlinear damping vibrations of the cutting tool are taken into consideration in the model. This approach allows defining the following system properties: branching equilibrium points; the conditions under which generated limit cycles and invariant tori; the formation of chaotic dynamics. The dynamic subsystem tool is presented as the linear dynamical system in the normal plane. The main attention is paid to the analysis of bifurcations in the space of parameters of dynamic equations, as well as in the space of control parameters. General patterns of loss of stability of equilibrium of the system are considered. The role of acceleration of gyroscopic and circulation forces is specified. The results are important for the analysis of motion of mechanical systems that interact with various environments (processes of friction, hydrodynamic, aerodynamic, etc.).
Keywords: processing, metal cutting, dynamic system, asymptotic stability, invariant manifolds, bifurcation
WSEAS Transactions on Applied and Theoretical Mechanics, ISSN / E-ISSN: 1991-8747 / 2224-3429, Volume 10, 2015, Art. #11, pp. 102-116
Title of the Paper: Optimization of Material Removal Rate of AlMg1SiCu in Turning Operation using Genetic Algorithm
Authors: Rahul Dhabale, Vijaykumar S. Jatti
Abstract: In the present study genetic algorithm was used to optimize the turning process parameters to obtain maximum material removal rate. The prediction of optimal machining condition for material removal rate plays an important role in process planning. Thus the objective of present study was to develop an empirical model to predict material removal rate in terms of spindle speed, feed rate and depth of cut using multiple regressions modeling method. Experiments were carried out on NC controlled machine tool by taking AlMg1SiCu as workpiece material and carbide inserted cutting tool. Finally, genetic algorithm has been employed to find out the optimal setting of process parameters that optimize material removal rate. The best response value for material removal rate obtained from single objective optimization by genetic algorithm was 6021.411 mm3/min. Comparisons of experimental and predicted results at optimum conditions showed an error of 3.35 %.This provides flexibility to the manufacturing industries to choose the best setting depending on applications.
Keywords: Genetic algorithm, Aluminum alloy, Taguchi approach, Analysis of variance, Regression modeling, Material removal rate
WSEAS Transactions on Applied and Theoretical Mechanics, ISSN / E-ISSN: 1991-8747 / 2224-3429, Volume 10, 2015, Art. #10, pp. 95-101
Title of the Paper: Adaptive Finite Element Simulation of Sheet Forming Operations Using Continuum Elements
Authors: Mohd. Ahmed
Abstract: Presented in this study is the recovery techniques based adaptive finite element analysis of sheet forming operations. An adaptive finite element code AdSheet2 considering continuum elements has been developed. The code allows the analysis of sheet forming operations and gives the distribution of adaptively refined mesh, effective strain, and punch load, stress and strain rate tensor in the domain. The recovery scheme for determining more accurate velocity field is based on the least squares fitting of the computed velocities in element patches. The solution error is estimated on the basis of an energy norm. The code is used to simulate an axi-symmetric stretching of a metal blank by a hemispherical punch. The numerical results of the adaptive analysis are presented and compared with non-adaptive analysis. The results presented show that the performance of the adaptive analysis in predicting the deformation behaviour i.e. the seats of large deformations, instability and effect of contact conditions is much superior.
Keywords: Stress Recovery, Velocity Recovery, Adaptive Mesh Refinement, Sheet Forming Operations, Finite Element Analysis, Error Estimators
WSEAS Transactions on Applied and Theoretical Mechanics, ISSN / E-ISSN: 1991-8747 / 2224-3429, Volume 10, 2015, Art. #9, pp. 83-94
Title of the Paper: Probability Calculation for Natural Frequency of Anisotropic Stator Core of Large Turbo-Generator
Authors: Yixuan Wang
Abstract: Techniques for vibration reduction and design of stator core require knowledge of its modal frequencies, which depend on the geometry shapes, dimensions and material properties. The material properties of stator core are mainly related to its laminated process and assembly as well as the operating temperature of turbo-generator. It is found that the generally accepted value of material properties is not valid for the stator core with laminated silicon steel slice and operating at about 110-120 Celsius. This paper simply summarizes the method of determining elastic constants of stator core material, and then introduces a simple and effective method for the calculation of the modal frequencies of stator core. The material model of stator core is thought anisotropic. The elastic modulus, Poisson’s ratio, and mass density are all considered as uncertainty variables, obeying Gaussain distribution, and changing in the possible range; and then ANSYS workbench 14.5 program is used to determine the resonant frequencies and corresponding probability of stator core ,and response surfaces of natural frequencies vs. elastic constants by statistical method (Six Sigma Analysis). The results have an important guiding role for the laminated structure design, manufacture process, the fixedness and the vibration isolation design of stator core.
Keywords: Large turbo-Generator, Anisotropic Stator Core, Material Properties, Natural Frequency, Six Sigma Analysis
WSEAS Transactions on Applied and Theoretical Mechanics, ISSN / E-ISSN: 1991-8747 / 2224-3429, Volume 10, 2015, Art. #8, pp. 71-82
Title of the Paper: Wave Propagation in an Irregular Fluid Saturated Porous Anisotropic Layer Sandwiched between a Homogeneous Layer and Half Space
Authors: Ravinder Kumar, Dinesh Kumar Madan, Jitander Singh Sikka
Abstract: The propagation of shear waves in an anisotropic fluid saturated porous layer sandwiched between homogeneous isotropic layer and isotropic half-space with irregularity present at the interface, has been examined. The dispersion equation for shear waves is derived by using the perturbation technique. The effect of wave number and irregularity are studied numerically. Also the dispersion curves for different size of irregularity are compared graphically with the help of MATLAB. This study shows that the phase velocity is significantly influenced by the wave number and the size of irregularity.
Keywords: Shear waves, Anisotropic layer, Dispersion Equation, Perturbation Technique, MATLAB
WSEAS Transactions on Applied and Theoretical Mechanics, ISSN / E-ISSN: 1991-8747 / 2224-3429, Volume 10, 2015, Art. #7, pp. 62-70
Title of the Paper: Surface Accuracy Analysis of Single Panels for the Shanghai 65-M Radio Telescope
Authors: Li Fu, Guoxi Liu, Chao Jin, Feng Yan, Tao An, Zhiqiang Shen
Abstract: We presented the surface accuracy measurements of 5 single panels of the Shanghai 65-meter radio telescope by employing the coordinate measuring machine and laser tracker. The measurement data obtained from the two instruments were analyzed with the common point transformation and CAD surface fitting techniques, respectively. The derived rms uncertainties of panel accuracy from two methods are consistent with each other, and both match the design specification. The simulations of the effects of manufacturing error, gravity, temperature and wind on the panel surface accuracy with the finite element analysis method suggest that the first two factors account for primary sources of the accuracy uncertainty. The panel deformation under concentrated load was analyzed through finite element analysis and experiment, and the comparison error is 5.6%. There is not plastic deformation when people of weight below 70kg installs and remedies the panel.
Keywords: antennas, finite element methods, measurement, accuracy, panel
WSEAS Transactions on Applied and Theoretical Mechanics, ISSN / E-ISSN: 1991-8747 / 2224-3429, Volume 10, 2015, Art. #6, pp. 54-61
Title of the Paper: Investigation into the Effect of Aluminium Powder on Mechanical, Tribological and Electrical Properties of Al-Abs Composites
Authors: Meena Laad, Vijaykumar S. Jatti
Abstract: Nowadays many advanced technological processes require materials with unusual combinations of properties that cannot be provided by the traditional polymers, ceramics, and metal alloys. Because of these the focus is shifted from the pure/traditional material to the composites/hybrid materials for manufacturing the product. In view of this objective of the present study was to investigate the effect of different composition of aluminium (Al) powder on the mechanical properties of the ABS-Al composites. Three different compositions of ABS-Al composite with different weight percentage of surfactant material were prepared using injection molding machine. Mechanical properties such as tensile strength, flexural strength, impact strength and hardness test, tribological properties and electrical resistivity test were performed on these composites as per ASTM standard. Experimental results showed that the mechanical properties of composites are less in comparison to plain ABS. Hardness of Al-ABS composites is low in comparison to plain ABS material. This is due to the fact that the aluminium is soft material and undergoes more deformation resulting in low hardness value. Wear test results showed that the height loss and coefficient of friction of composites is more in comparison to plain ABS. Electrical resistivity of composites is less than the plain ABS and the resistivity decreases as the aluminium percentage increases in the composites. This is due to the fact that ABS is a bad conductor of electricity and aluminium is good conductor of electricity. Thus, this study reveals that based on applications a particular type of Al-ABS composite can be used.
Keywords: Polymer composites, Acrylonitrile Butadiene Styrene, Tensile test, Flexural test, Impact test, ABS-Al Composites
WSEAS Transactions on Applied and Theoretical Mechanics, ISSN / E-ISSN: 1991-8747 / 2224-3429, Volume 10, 2015, Art. #5, pp. 47-53
Title of the Paper: Detection of Metal Fibres in Cementitious Composites Based on Signal and Image Processing Approaches
Authors: Jiri Vala, Leonard Hobst, Vladislav Kozak
Abstract: Mechanical properties of cementitious composites, reinforced by metal fibres, are conditioned by the volume fraction and distribution of directions of fibres. However, their reliable non-destructive or low-invasive experimental evaluation is a serious problem. The paper pays attention to four classes of such indirect methods. The first class relies on the planar X-ray imaging, with the discrete fast Fourier transform applied to image processing. The second one applies the magnetic approach, with certain electromagnetic alternative. The third one comes from the computed tomography, as an unique exact method for the detection of volume fraction without breaking the sample, with an information on (an)isotropy as a benefit. The last one is concentrated to the FEM modelling. Examples related to all sketched method from the experiments performed at the Brno University of Technology show the advantages and restrictions of particular approaches.
Keywords: Cementitious composites, non-destructive testing, signal and image processing, computational simulation
WSEAS Transactions on Applied and Theoretical Mechanics, ISSN / E-ISSN: 1991-8747 / 2224-3429, Volume 10, 2015, Art. #4, pp. 39-46
Title of the Paper: The Force Vacuum Field as an Alternative to the Ether and Quantum Vacuum
Authors: Sergey G. Fedosin
Abstract: The vacuum field is considered as a force field, which consists of particles moving at speeds of the order of the speed of light, such as neutrinos, photons and charged cosmic rays. This distinguishes it from the classical static ether and some models of the quantum vacuum. In the presented model the occurrence of gravitational and electromagnetic force is substantiated, some vacuum field parameters are predicted, the sources that generate the vacuum field are suggested based on the theory of infinite nesting of matter.
Keywords: vacuum field, graviton field; ether, quantum vacuum
WSEAS Transactions on Applied and Theoretical Mechanics, ISSN / E-ISSN: 1991-8747 / 2224-3429, Volume 10, 2015, Art. #3, pp. 31-38
Title of the Paper: Simulation Analysis of Vibration Shock on Tank Aiming Mirror
Authors: Shoujun Wu, Guoquan Ren, Dongwei Li
Abstract: Vibration, especially at the circumstances of accidental falling down, always cause great damage to tank aiming mirror. Therefore, during the process of designing tank aiming mirror we need to consider how to reduce the harmful influence of external forces. The paper sets up a simplified second order vibration system and a dynamic model in the ADAMS. We make different simulation analysis on different heights of tank crash?Paper studies the change rule of the angular displacement, angular velocity, angular acceleration and contact force of reflector when it suffers different impact force. The study provides an effective research means for vibration analysis of photoelectric equipment. Results show that angle in pitch changes greater than that in azimuth, which not only provides an important reference for the designer, but also improves the tank aiming mirror’s environmental adaptability.
Keywords: Tank Aiming Mirror, ADAMS, Dynamics Model, Simulation Analysis
WSEAS Transactions on Applied and Theoretical Mechanics, ISSN / E-ISSN: 1991-8747 / 2224-3429, Volume 10, 2015, Art. #2, pp. 24-30
Title of the Paper: Parametric Excitation and Suppression of Oscillations at the Interfaces of Continua for the Processes’ Control in Jet and Film Flows, Channel Flows with Phase Change and in Granular Media
Authors: Ivan V. Kazachkov
Abstract: The problem is interesting theoretically and important for the practical applications in three aspects: 1. Excitation of parameters’ oscillations in continua in touch with intensification of various technological and technical processes: heat and mass transfer, mixing, decreasing the viscosity, improving the quality for crystallizing metal and many other phenomena. 2. Excitation of parameters’ oscillations in touch with necessity of disintegration of jet and film flows: air spray, spray-coating, metal spraying, dispersing and granulation of materials (e.g. particles’ producing from molten metals), etc. 3. Suppression of oscillations for stabilization of unstable regimes and processes: jet-drop and film screens for protection of diaphragm of experimental thermonuclear reactor, thermal instability and fusion control in reactor, control of electromechanical and electrochemical instabilities, combustion stability, decreasing the hydrodynamic and acoustic resistance, etc. In some cases, parametric control makes possible not just intensification the processes but also running such processes, which are impossible without parametric control. A lot of different linear as well as nonlinear model situations have been considered. As a result some interesting peculiarities of parametric wave excitation and suppression in film flows including three new phenomena of parametric film decay were revealed: resonant decay, soliton-like decay and shock-wave decay. The phenomena were first theoretically predicted and then experimentally invented and investigated. Based on these new phenomena we developed, created and tested the prospective dispersion and granulation machines for some metals and other materials.
Keywords: Parametric, Wave, Excitation, Suppression, Instability, Stabilization, Control, Disintegration, Film Flow, Jet, Solidification Front, Granular Media
WSEAS Transactions on Applied and Theoretical Mechanics, ISSN / E-ISSN: 1991-8747 / 2224-3429, Volume 10, 2015, Art. #1, pp. 1-23