WSEAS Transactions on Applied and Theoretical Mechanics
Print ISSN: 1991-8747
E-ISSN: 2224-3429
Volume 9, 2014
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 9, 2014
Title of the Paper: System Identification of Building Structures with Continuous Modeling
Authors: Ruichong Zhang, Fadi Sawaged, Lotfi Gargab
Abstract: This paper introduces a wave-based approach for system identification of high-rise building structures with a pair of seismic recordings, which can be used to evaluate structural integrity and detect damage in post-earthquake structural condition assessment. The fundamental of the approach is based on wave features of generalized impulse and frequency response functions (GIRF and GFRF), i.e., wave responses at one structural location to an impulsive motion at another reference location in time and frequency domains respectively. With a pair of seismic recordings at the two locations, GFRF is obtainable as Fourier spectral ratio of the two recordings, and GIRF is then found with the inverse Fourier transformation of GFRF. With an appropriate continuous model for the structure, a closed-form solution of GFRF, and subsequent GIRF, can also be found in terms of wave transmission and reflection coefficients, which are related to structural physical properties above the impulse location. Matching the two sets of GFRF and/or GIRF from recordings and the model helps identify structural parameters such as wave velocity or shear modulus. For illustration, this study examines ten-story Millikan Library in Pasadena, California with recordings of Yorba Linda earthquake of September 3, 2002. The building is modeled as piecewise continuous layers, with which GFRF is derived as function of such building parameters as impedance, cross-sectional area, and damping. GIRF can then be found in closed form for some special cases and numerically in general. Not only does this study reveal the influential factors of building parameters in wave features of GIRF and GRFR. It also shows some system-identification results, which are consistent with other vibration- and wave-based results. Finally, this paper discusses the effectiveness of the proposed model in system identification.
Keywords: Wave-based approach, Seismic responses of buildings, Wave propagation in structures
WSEAS Transactions on Applied and Theoretical Mechanics, ISSN / E-ISSN: 1991-8747 / 2224-3429, Volume 9, 2014, Art. #30, pp. 308-316
Title of the Paper: The Gutenberg - Richter Law Deviations Due to Random Distribution of Block Sizes
Authors: B. P. Sibiryakov, A. V. Kopeykin
Abstract: This paper studies properties of a continuum with structure. The characteristic size of the structure governs the fact that difference relations do not automatically transform into differential ones. It is impossible to consider an infinitesimal volume of a body, to which we could apply the major conservation laws, because the minimal representative volume of the body must contain at least a few elementary microstructures. The corresponding equations of motions are the equations of infinite order, solutions of which include, along with sound waves, the unusual waves propagating with abnormal low velocities, not bounded below. It is shown that in such media weak perturbations can increase or decrease outside the limits. The number of complex roots of the corresponding dispersion equation, which can be interpreted as the number of unstable solutions, depends on the specific surface of cracks and is an almost linear dependence on a logarithmic scale, as in the seismological law of Gutenberg-Richter. If the distance between one pore (crack) to another one is the random value with some distribution, we must write another dispersion equation and examine different scenarios depending on statistical characteristics of the random distribution. In this case, there are sufficient deviations from Gutenberg-Richter law, and this theoretical result corresponds to some field and laboratory observations.
Keywords: specific surface, operator of continuity, equation of motion, structured media, catastrophes
WSEAS Transactions on Applied and Theoretical Mechanics, ISSN / E-ISSN: 1991-8747 / 2224-3429, Volume 9, 2014, Art. #29, pp. 301-307
Title of the Paper: Numerical and Experimental Acoustic Performance Investigations of a High-Speed Train Composite Sandwich Panel
Authors: D. Siano, M. Viscardi, P. Napolitano, M. A. Panza
Abstract: Present work focuses on the implementation of numerical and experimental analyses aimed to acoustic performances characterization of a composite sandwich panel used for a high-speed train. Firstly, an experimental and a numerical modal analyses are presented. Starting from both FE simulation and impact testing outcomes, it has been possible to carry out a correlation study through the computation of the Modal Assurance Criterion (MAC). Good agreement between numerical and experimental analyses has been found, therefore the definition of a reliable FE model has been obtained without the necessity of implementing a sensitivity and updating procedure. In this paper, to find a convenient and accurate mean for predicting the panel Transmission Loss parameter, the panel is modeled as a composite sandwich panel, and its TL is predicted with the hybrid FE&SEA (Statistical Energy Analysis) method. The TL result is then compared to the experimental one, carried out through the employment of an intensity sound probe. A very good agreement has been found allowing to use such numerical procedure for further acoustic performances improvements. Hence, future developments could regard the possibility to implement a Reverse Engineering procedure, in order to realize an optimization process by considering different materials and stratifications or different panel thicknesses, to improve the acoustic attenuation properties at those frequencies at which a worse acoustic behavior of the panel, is present.
Keywords: Sandwich Panel, FE/Test Modal Analyses Correlation, Noise Reduction, BEM simulation
WSEAS Transactions on Applied and Theoretical Mechanics, ISSN / E-ISSN: 1991-8747 / 2224-3429, Volume 9, 2014, Art. #28, pp. 290-300
Title of the Paper: Numerical Study of Hydraulic Flux through a Saturated and Inhomogeneous Porous Medium by Means of the FEM
Authors: A. W. Faria, J. A. Martins, E. C. Romão
Abstract: This paper presents the study of water flux in saturated porous medium, homogeneous and inhomogeneous, by the development of particular numerical tool with Finite Element Method (FEM) and formulated in FORTRAN programming language. The finite element model, developed at this article, uses hexahedron finite elements with 8 or 27 nodes. The hydraulic percolation is analyzed by the flux and potential hydraulics determination in soil with sheet piles structures. The study of the massive comprises either clay or clay plus iron mining waste. These numerical applications aims to validate the numerical method implemented using FEM as well as by numerical comparison with similar studies made by other researchers.
Keywords: Flux through a saturated porous medium, anisotropic soil, sheet piles structures, Finite Element Method
WSEAS Transactions on Applied and Theoretical Mechanics, ISSN / E-ISSN: 1991-8747 / 2224-3429, Volume 9, 2014, Art. #27, pp. 282-289
Title of the Paper: Investigation on the Contact Hardening of Al/Steel Laminated Composites with Soft Interlayers
Authors: Leonid Gurevich, Yuriy Trykov, Dmitry Pronichev, Mikhail Trunov
Abstract: The study presents results of finite element simulations and experimental investigations of tensile tests of the laminated metal Al alloy/steel composite with soft aluminum interlayer. The results were obtained for the range of interlayer thicknesses and different interlayer strength values. The relative interlayer thickness value corresponding to the rupture of the aluminum alloy was identified.
Keywords: Laminated composites, steel, aluminum, soft interlayer, explosion welding
WSEAS Transactions on Applied and Theoretical Mechanics, ISSN / E-ISSN: 1991-8747 / 2224-3429, Volume 9, 2014, Art. #26, pp. 275-281
Title of the Paper: Nonlinear Modeling of Helical Gear Pair with Friction Force and Frictional Torque
Authors: Qinglin Chang, Li Hou, Zhijun Sun, Yongqiao Wei, Yunxia You
Abstract: Helical gear transmission is widely used in various industrial departments. The dynamic characteristic of helical gear system is very important and attracts scholar’s attention all around the world. A lot of dynamic models have been put forward. But the models consisted time-varying friction force and frictional torque are very few. So a dynamic model contained time-varying friction force and frictional torque is proposed by a new algorithm which is developed by Chinmaya Kar. Then the dimensionless method was used, and the dimensionless dynamic model was summarized. At last, through the numerical method, the nonlinear characteristics in particular parameters were studied.
Keywords: Time-varying frictional force, contact line, helical gear, nonlinear characteristic
WSEAS Transactions on Applied and Theoretical Mechanics, ISSN / E-ISSN: 1991-8747 / 2224-3429, Volume 9, 2014, Art. #25, pp. 264-274
Title of the Paper: Reactionless Motion Explained by the Laws of the Nonlinear Dynamics Leading to a New Method to Explain and Calculate the Gyroscopic Torque and its Possible Relation to the Spin of Electron
Authors: Bojidar Djordjev
Abstract: On one hand the extant mechanics is based on the understanding that the six degrees of freedom are mutually isolated i.e. momentums and angular momentums can not “jump” from one to another degree of freedom. This is a natural consequence of the Newtonian Laws of Dynamics. But the natural example of gyroscope demonstrates that if a body rotates about axis X and turns about Y, a gyroscopic torque generates about Z in fact demonstrates that under some circumstances the degrees of freedom can be connected in system. The accepted explanation of the phenomenon by means of the method of the vector multiplication in criticized and in fact it just models the phenomenon. The Author’s experience shows that the gyroscopic torque is a result of the inertial effect of the changed direction of the orbiting masses in the plane of turning. We can determine the inertial effect of the changed direction using the Newtonian Laws of Dynamics. Then we realize that the First Newtonian Law states that speed and direction are equal in rights conserved values but on the other hand the Second and Third Newtonian Laws formulate the inertial effect of the changed speed in the frame of the given direction only. So we need to formulate parallel Laws formulating the inertial effect of the changed direction. Applying these understandings to the gyroscopic torque we formulate a new formula showing that the gyroscopic torque depends on the sine function of the correlation between the angular speeds of turning and rotation. We find that the new formula and the one of the vector multiplication calculate almost equal results if the angular speed of rotation is much bigger then the one of turning. Then we find the condition. Exploring the sine function we find that the body does not generate gyroscopic torque if the angular speed of rotation is 1/2 of the one of the turning. Possibly, it corresponds to the 1/2 spin of electron. The paper is an extended version of the already published one [1].
Keywords: Reactionless motion, Classical mechanics, vector multiplication, gyroscopic torque, spin of electron
WSEAS Transactions on Applied and Theoretical Mechanics, ISSN / E-ISSN: 1991-8747 / 2224-3429, Volume 9, 2014, Art. #24, pp. 252-263
Title of the Paper: Investigation into Application of Electrical Discharge Machining as a Surface Treatment Process
Authors: Meena Laad, Vijaykumar S. Jatti, Pratik Prakash Jadhav
Abstract: Titanium alloys are recognized as difficult o machine materials because of their susceptibility to work hardening during machining by conventional machining processes. This problem can be overcome by using electrical discharge machining (EDM) an unconventional machining process. In some of the researches it is reported that machining of workpiece by using EDM process modifies the surface properties of the base material. Hence, the objective of this study is to investigate the improvement in surface properties of titanium alloy (Grade 5) machined by die sinking EDM process using graphite electrode. Gap current, pulse on time, and pulse off time were taken as EDM process parameter and micro-hardness was taken as the response characteristics. From the experimental analysis it was found that pulse off time plays an important role in enhancing the surface hardness of the specimen. This is due to migration of carbon from the tool electrode and dielectric onto the surface of workpiece. This increase in the micro hardness can be taken as the indicator of surface alloy. Presence of titanium carbide (TiC) indicates that its formation is taking place in the plasma channel and the same was confirmed by the X-ray diffraction analysis.
Keywords: Ti alloy, Electrical discharge machining, Scanning electron microscopy, X-ray diffraction, Micro hardness
WSEAS Transactions on Applied and Theoretical Mechanics, ISSN / E-ISSN: 1991-8747 / 2224-3429, Volume 9, 2014, Art. #23, pp. 245-251
Title of the Paper: Calculation Method for Structural Fire Resistance. Calculation Method Validation
Authors: Diana Ancas, Bogdan Ungureanu
Abstract: The paper concisely presents the calculation methods of structural fire resistance for buildings, the conditions that an advanced calculation method should accomplish in order to be used for calculation, and also the additional validation of numeric analysis programme SAFIR for fire stressed structures. The validation is achieved using the results of a fire test relevant for numeric calculation validation of fire resistance for structural pillars of Bucharest Tower Center, and that is the fire test of the octagonal pillar with cross steel profiles, with concrete between the visible blooms of steel profiles, tested by ARBED – RECHERCHES Luxembourg.
Keywords: fire resistance, temperature, thermal response, structural element
WSEAS Transactions on Applied and Theoretical Mechanics, ISSN / E-ISSN: 1991-8747 / 2224-3429, Volume 9, 2014, Art. #22, pp. 238-244
Title of the Paper: A New Model for Predicting of Stresses on the Compound Extrusion Container
Authors: Yuanxin Luo, Yikun Xiong, Yongqing Wang, Ling Ma
Abstract: The extrusion process is widely used for forming aluminum and titanium alloy parts or products. A material is fed into the extrusion container for pushing through a die to create parts with a fixed cross-sectional profile. The extrusion container is one of the most key components that supports extremely high pressure (>700MPa) in the extrusion process. Therefore, the compound extrusion container is designed for reduce the peak of stresses to increase its reliability. The stresses distribution is largely depended on the interferences and layer thicknesses. In this paper, a new analytical model based on Direction Displacement Method (DDM) is proposed for predicting the stress distribution on the multi-layer container. The stresses distribution on the container after assembly and normal working are computed by using this model. Four cases are studied to verify the fidelity of the proposed model. Finally, discussions and concluding remarks are also given.
Keywords: Extrusion process, Extrusion container, Direction Displacement Model (DDM), Finite Element Method (FEM)
WSEAS Transactions on Applied and Theoretical Mechanics, ISSN / E-ISSN: 1991-8747 / 2224-3429, Volume 9, 2014, Art. #21, pp. 229-237
Title of the Paper: Influence of Heat Input on Mechanical Properties and Microstructure of Austenitic 202 Grade Stainless Steel Weldments
Authors: Apurv Choubey, Vijaykumar S. Jatti
Abstract: Present research work investigates the effect of heat input (controlled by welding current, welding voltage and welding speed) on tensile strength, micro-hardness and microstructure of austenitic 202 grade stainless steel weldments produced by shielded metal arc welding (SMAW). The base material used in the present investigation was Cr-Mn SS and 308L SS solid electrode was used as the filler material. From the experimental results it was found that the increase in heat input affects the micro-constituents of base metal, and heat affected zone (HAZ). Tensile strength decreases with increase in heat input and from scanning electron microscopy of tensile test fractured surfaces exhibited ductile & brittle failure. From micro hardness data values it was observed that hardness of material increases with increase in heat input in weld pool and decreases in HAZ zone. Optical microscopy shows that smaller dendrite sizes and lesser inter-dendritic spacing were observed in the fusion zone at low heat input. And long dendrite sizes and large inter-dendritic spacing were observed in the fusion zone of the joint welded at high heat input. Further it was observed from the optical micrographs that the extent of grain coarsening in the HAZ increases with increase in heat input.
Keywords: Austenitic stainless steel, Heat affected zone, Micro-hardness, Shielded metal arc welding, Ductile facture, Ultimate tensile strength
WSEAS Transactions on Applied and Theoretical Mechanics, ISSN / E-ISSN: 1991-8747 / 2224-3429, Volume 9, 2014, Art. #20, pp. 222-228
Title of the Paper: Control of the Forces of Gravity: Modeling and Experimental Verification
Authors: Vitaly Groppen
Abstract: Paper describes statement and results of experiments which are based on the use of high voltage for verification of a gravity control possibility. Used verification technology is based on the idea of substitution of energy distributed in the neighborhood above the upper surface of the plate-deployed capacitor by the material point with the equivalent mass: force of the gravitational interaction of the plate with this point has opposite direction to the force of gravitational interaction of this plate with the Earth thus reducing this force. Results of experiments with different samples confirm the correctness of the proposed approach.
Keywords: Experimental verification, modeling, energy, gravity control, gravitational interaction, high voltage, sample, deployed capacitor, weight measurement
WSEAS Transactions on Applied and Theoretical Mechanics, ISSN / E-ISSN: 1991-8747 / 2224-3429, Volume 9, 2014, Art. #19, pp. 215-221
Title of the Paper: An Efficient Error Indicator with Mesh Smoothing for Mesh Refinement: Application to Poisson and Laplace Problems
Authors: Zhaocheng Xuan, Yaohui Li, Hongjie Wang
Abstract: An efficient mesh refinement method for h-version finite element analysis is presented based on both an a-posteriori error indicator and the geometrical quality of mesh. The first step is to refine the meshes on which the a-posteriori error indicators are relatively higher than the others. The error indicators are obtained by simplifying the computation of error bounds which are obtained by solving elemental Neumann type subproblems with the averaged flux for the consistency of the Neumann problems. The simplification of computation means that the functional space on the mesh uniformly refined with only half size of the coarse mesh is chosen as the test functional space in the elemental residual form of error equations, thus the cost for computing the error indicators is quite low. After refinement, some refined triangles will become poorly shaped or distorted, then the second step is to move the meshes to improve their geometrical quality with Laplacian smoothing algorithm. Two examples are computed to verify this method and the results show that the refined mesh obtained by both the a-posteriori error indicator and mesh smoothing gives the optimal convergence and higher accuracy for the results.
Keywords: Finite elements; Mesh refinement; Error indicator; Mesh smoothing; Implementation
WSEAS Transactions on Applied and Theoretical Mechanics, ISSN / E-ISSN: 1991-8747 / 2224-3429, Volume 9, 2014, Art. #18, pp. 206-214
Title of the Paper: Hall Current and Thermal Radiation Effect on MHD Convective Flow of an Elastico-Viscous Fluid in a Rotating Porous Channel
Authors: Saswati Purkayastha, Rita Choudhury
Abstract: A theoretical analysis is carried out to study the heat and mass transfer effects on elastico-viscous fluid flow in a vertical porous channel with rotation and Hall current. The two porous plates are subjected respectively to constant injection and suction velocity. A magnetic field of uniform strength is applied in the direction perpendicular to the plates. The induced magnetic field is neglected due to the assumption of small magnetic Reynolds number. The elastico-viscous fluid flow is characterized by Walters liquid (Model B/).The analytical solutions to the coupled non-linear equations governing the motion are obtained by regular perturbation technique. The effects of rotation, buoyancy force, magnetic field, thermal radiation and heat generation parameters on resultant velocity and temperature fields are analyzed and illustrated graphically in possible cases. The importance of the problem can be seen in cooling of electronic components of a nuclear reactor, bed thermal storage and heat sink in the turbine blades.
Keywords: Elastico-viscous, Hall current, Walters liquid (Model B/), perturbation, MHD, radiation
WSEAS Transactions on Applied and Theoretical Mechanics, ISSN / E-ISSN: 1991-8747 / 2224-3429, Volume 9, 2014, Art. #17, pp. 196-205
Title of the Paper: Design of a One–Dimensional Multilayer Si / SiO2 Photonic Crystals for Thermophotovoltaic Filters
Authors: Samah G. Babiker, Shuai Yong, Mohamed Osman Sid-Ahmed, Xie Ming
Abstract: In this paper, a one - dimensional multilayer is optimized for potential applications as thermophotovoltaic (TPV) selective filter. The proposed TPV filter was fabricated through a magnetron sputtering process by using the radio frequency (RF) magnetron sputtering system. The spectral reflectance and transmittance of the proposed TPV filter are measured by using spectral transmittance and reflectance measurement system at wavelength from 0.3μm to 2.5μm at near normal incident 8°.The bidirectional reflectance/transmittance distribution function BRDF/BTDF are measured by three axis automated scatterometer (TAAS). The calculated spectral reflectance and transmittance of the proposed TPV selective filter has shown several peaks and large oscillations, due to the refractive index mismatch between the proposed TPV filter sample and substrate. The measured results show that the proposed filter has high transmittance value in the spectral range of λ<=1.73μm and high BTDF•cosθ value for both of the TE and TM polarization. It also has low BRDF•cosθ value at normal incidence due to detector blocks the laser beam. The measured results are in good agreement with the simulation results. The spectral efficiency of the TPV system with the proposed selective filter is above than 0.43 at emitter temperature >1600K. The results show that the 1D 8-layer Si/SiO2 sample, if used as a selective filter with a low band gap photovoltaic cell (GaSb), would lead to high TPV overall efficiency and high electrical output power. All numerical results are obtained by using the rigorous coupled-wave analysis (RCWA) method.
Keywords: Thermophotovoltaic, Selective filter, Rigorous coupled wave analysis (RCWA), a magnetron sputtering process, spectral transmittance, bidirectional reflectance/transmittance distribution function
WSEAS Transactions on Applied and Theoretical Mechanics, ISSN / E-ISSN: 1991-8747 / 2224-3429, Volume 9, 2014, Art. #16, pp. 187-195
Title of the Paper: Joining of Dissimilar Aluminium Alloys AA2014 T651 and AA6063 T651 by Friction Stir Welding Process
Authors: Ranjith R., Senthil Kumar B.
Abstract: In this work joining of two dissimilar aluminium alloys AA2014 T651 and AA6063 T651 was carried out using friction stir welding. The weld was obtained by varying its tilt angle (2◦-4◦), tool offset (0.5mm towards AS, centre line, 0.5mm towards Rs) and Pin diameter (5mm – 7mm). Tensile strength & %Elongation was carried out to evaluate the strength of the weld. Optical microscope study was carried out to study the uniform stirring of materials. The result shows that better interlocking and bonding of materials occurs at 4 degree tilt angle. The tensile strength is better when the tool is offset towards AA2014 side because of complete fusion of harder material. When, it is offset towards AA6063 side results in insufficient heat generation on advancing side. This leads to incomplete fusion of AA2014. Pin diameter has greatest impact on heat generation. The 6 mm pin diameter, 4 degree tilt angle and 0.5 mm offset towards advancing side give the optimum tensile strength of 371 MPa.
Keywords: Friction Stir Welding, Dissimilar Alloy, Stirring of Materials, Tensile Strength
WSEAS Transactions on Applied and Theoretical Mechanics, ISSN / E-ISSN: 1991-8747 / 2224-3429, Volume 9, 2014, Art. #15, pp. 179-186
Title of the Paper: Mixed Finite Element Method for Linear Elasticity in a Cracked Domain
Authors: M. A. Bennania, Abdeslam El Akkadb, Ahmed Elkhalfia
Abstract: A mixed finite element procedure for plane elasticity system in a cracked domains is introduced and analyzed. There is a member of the family for each polynomial degree, beginning with degree two for the stress and degree one for the displacement, and each is stable and affords optimal order approximation. The simplest element pair involves 24 local degrees of freedom for the stress and 6 for the displacement. We also construct a lower order element involving 21 stress degrees of freedom and 3 displacement degrees of freedom which is, we believe, likely to be the simplest possible conforming stable element pair with polynomial shape functions. The mixed formulation is used in elasticity for incompressible materials such as rubber, its use for linear elasticity has been discussed by many researchers, in this section we will study the compatibility of the mixed formulation cracked domains and compare it with the conventional method.The numerical results are compared with some previously published works or with others coming from commercial code.
Keywords: Elasticity problem; mixed finite element method; Lower order element; linear fracture mechanics
WSEAS Transactions on Applied and Theoretical Mechanics, ISSN / E-ISSN: 1991-8747 / 2224-3429, Volume 9, 2014, Art. #14, pp. 167-178
Title of the Paper: Material Migration and Surface Improvement of OHNS Die Steel Material by EDM Method using Tungsten Powder-Mixed Dielectric
Authors: Nitin K. Khedkar, T. P. Singh, Vijaykumar S. Jatti
Abstract: Material migration and surface improvement using electrical discharge machining has become a key research area in the last two decades. Material may migrate to the machined surface of workpiece either from the tool electrode or from powder mixed in dielectric. This paper reports the results of experimental study carried out to evaluate the improvement in machined surface properties of OHNS die steel machined by electrical discharge machining using tungsten powder mixed in the dielectric medium. Gap current, pulse on time and pulse off time were taken as process parameters and micro-hardness of the machined surface was taken as the response parameter. Scanning electronic microscopy showed the topography of the machined surface, there are discrete craters along with some volcanic features, and many spherical droplets left on the EDmed surface, which indicate that the material removal mechanism is melting and evaporation. Spectroscopic and EDS analysis show substantial transfer of tungsten and carbon to the workpiece surface and an improvement of more than 100% in micro-hardness for all the trial conditions. Presence of tungsten was observed on all machined surfaces in the form of intermetallic compounds with iron, as carbides and in the form of alloyed cementite. Presence of carbon was observed on all machined surfaces in the form of solid solutions in ferrite and cementite phases or their independent hard carbides. These formations caused significant increase in microhardness. This was confirmed by the XRD analysis. Tribological analysis showed that coefficient of friction is higher for PMEDM work materials which shows significant rise in the microhardness than the parent material.
Keywords: Material migration, Surface improvement, Tungsten powder, Micro-hardness, Powder-mixed EDM, Scanning Electronic Microscopy, Energy Dispersive Spectroscopy
WSEAS Transactions on Applied and Theoretical Mechanics, ISSN / E-ISSN: 1991-8747 / 2224-3429, Volume 9, 2014, Art. #13, pp. 161-166
Title of the Paper: Parametric Examination including Brief Survey of Composite and Homogenous Closed Ended Cylindrical Pressure Vessels
Authors: Jacob Nagler
Abstract: This paper presents parametric design examination together with brief survey of composite and homogenous cylindrical pressure vessels with hemispherical ends. Two main kinds of composite and homogenous cylinders geometry were modeled and examined: thin and thick cylinders. Stress-strain relationships of the cylinders have been derived as a result of their model equation solution. Additionally, reinforced wrapping method effect on thin cylinder strength was presented and examined. Also, compound cylinder theory was discussed and main results were presented. Moreover, thick walled composite cylinders in polar coordinates theory has been developed and displayed together with other filament winding methods through analytic modeling and numerical examination. Finally, failure criteria of composed and homogenous cylinders were presented.
Keywords: Composite, Homogenous, Cylinder, Pressure vessel, Closed ended, Filament wound
WSEAS Transactions on Applied and Theoretical Mechanics, ISSN / E-ISSN: 1991-8747 / 2224-3429, Volume 9, 2014, Art. #12, pp.136-160
Title of the Paper: Interior Ballistic Two-Phase Flow Model of Guided-Projectile Gun System Utilizing Stick Propellant Charge
Authors: Mahmoud Rashad, Xiaobing Zhang, Hazem Elsadek
Abstract: Launching a guided projectile from conventional artillery is a very sensitive process for both the propelling charge and the gun system. Hence, a specific mathematical model based on two-phase fluid dynamics of solid single-perforated high density stick propellant and its products of combustion inside the gun tube during interior ballistics cycle is developed. The model includes the governing equations of mass, momentum and energy for both phases as well as the constitutive laws. The simulations are applied to conventional large caliber naval gun firing a guided projectile. The results are compared with the experimental data of granular propellant grains for validation. Different stick propellant grain design parameters are investigated. The grain size significantly affected the maximum chamber pressure and then the guided projectile muzzle velocity. An appropriate stick grain size condition exists, where the minimum pressure wave generation can obtained. Based on the simulation results, an apparent guideline for the proper design of stick propellant charge for launching guided projectiles is presented.
Keywords: Stick propellant, Two-phase flow, Interior ballistics, Guided-projectile
WSEAS Transactions on Applied and Theoretical Mechanics, ISSN / E-ISSN: 1991-8747 / 2224-3429, Volume 9, 2014, Art. #11, pp.124-135
Title of the Paper: The Calculated Justification of Seismic Stability of Load-Lifting Cranes
Authors: Nikolai Panasenko, Aleksei Sinelshchikov, Vadim Rabey
Abstract: To provide seismic safety for engineering structures remains a prevalent problem. In particular, attention is given to facilities whose destruction can cause damage to the population and the environment, such as the facilities that use nuclear energy. According to the maps of the general seismic regionalization OSR-97, independent spent fuel storage installation (ISFSI) with crane loadings of mining and chemical plant (MCP) (Zheleznogorsk, Krasnoyarsk Territory, Russian Federation) was related to 7 magnitude zones according to the MSK-64 scale. To justify the seismic safety using FEA, a dynamic spatial model of the MCP’s building was developed, which includes bridge cranes with lifting capacities of 160/32 t, 16/3.2 t and 15 t. The model was used for the floor accelerogram plotting at elevation marks of the cranes’ installment at +23 m, +16.8 m and +8.55 m and for the strength calculation of the supporting systems of the building using the dynamic analysis method (DAM) and the linear-spectral method (LSM). The equations of motion with multiple degrees of freedom of the dynamic model were solved using the numerical Gear method and the linear-spectral method (LSM). Based on the calculated floor accelerograms, the probability model of the seismic action was built in the form of probability-statistical floor accelerograms for the elevation marks of the cranes’ installment. The stress-strain state of the building and the bridge cranes was calculated under the seismic action conditions. The development of the LSM theory was proposed for the spatial constructions of industrial buildings with crane loadings. The efficiency of the proposed calculated methodology was established, and this proposed methodology was tested in the industrial sphere of a facility with nuclear energy usage that conforms to tightened seismic safety standards.
Keywords: Seismic safety, Industrial buildings, Load-lifting cranes, Earthquake accelerograms, Equations of motion, Stress-strain state
WSEAS Transactions on Applied and Theoretical Mechanics, ISSN / E-ISSN: 1991-8747 / 2224-3429, Volume 9, 2014, Art. #10, pp.104-123
Title of the Paper: One-Dimensional Si/SiO2 Photonic Crystals Filter for Thermophotovoltaic Applications
Authors: Samah G. Babiker, Yong Shuai, Mohamed O. Sid-Ahmed, Ming Xie
Abstract: In this paper, a one - dimensional Si/SiO2 photonic crystals (1D-PhCs) is optimized for potential application as thermophotovoltaic (TPV) optical filter. The performance of the proposed structure, 1D eightlayer Si/SiO2 of thermophotovoltaic system, is studied. The effect of the thickness of layers, incidence angle and number of periods on the spectral reflectance has been investigated by rigorous coupled-wave analysis (RCWA) method. Both the original proposed and the modified structures were prepared through a magnetron sputtering technique. The measured results are in good agreement with the simulated results. The spectral efficiency value of the modified structure is 33.5%at emitter temperature of about 1500 K .The measured results and simulated results have shown that the modification introduced in the 1D Si/SiO2 PhC has significantly improved the system performance.
Keywords: Filter, Photonic crystals, Reflectance Rigorous coupled wave analysis (RCWA), Thermophotovoltaic
WSEAS Transactions on Applied and Theoretical Mechanics, ISSN / E-ISSN: 1991-8747 / 2224-3429, Volume 9, 2014, Art. #9, pp.97-103
Title of the Paper: Variation of Material Properties of Cement Pastes with Various Types of Fly Ash During Maturation
Authors: Pavel Padevět, Tereza Otcovská, Ondřej Zobal
Abstract: The article describes properties of cement paste included addition various kinds of the fly ash. Firstly is described the preparation of the cement paste. The variation of material properties are described in time from one to three months. Next part is focused on the testing of the properties. Results of the testing are summarized in properties like a compression strength, Modulus of elasticity and tensile strength in bending. Finally the relation between material properties and volume weight is discussed. The article describes paste made from the same amount of cement and fly ash and mixed with water coefficient of 0.4.
Keywords: Cement Paste, Fly Ash, Compression Strength, Modulus of Elasticity, Water-cement Ratio, Cement-Fly Ash Ratio, Maturation of Cement Paste
WSEAS Transactions on Applied and Theoretical Mechanics, ISSN / E-ISSN: 1991-8747 / 2224-3429, Volume 9, 2014, Art. #8, pp.88-96
Title of the Paper: Gas-Solid Flow Model for Medium Caliber Naval Gun
Authors: Hazem El Sadek, Xiaobing Zhang, Mahmoud Rashad
Abstract: In this work the computational fluid dynamics for two-phase flow of the interior ballistic process is modeled. This model is solved numerically in order to predict the interior ballistic performance. The numerical simulation is carried out by MacCormack’s technique depending on the governing equations of the two-phase flow. A self-adapting method is used to expand the computational domain of the projectile motion. The moving control volume conservation method is used to adapt the moving boundary. This approach is applied to 76mm medium caliber naval gun with guided projectile. The simulation of the two-phase flow model with the projectile motion gives a good agreement between simulation results and experimental results.
Keywords: Guided projectile, interior ballistic, two-phase flow modeling, computational fluid dynamics, moving boundary
WSEAS Transactions on Applied and Theoretical Mechanics, ISSN / E-ISSN: 1991-8747 / 2224-3429, Volume 9, 2014, Art. #7, pp.80-87
Title of the Paper: Development of Benchmark Objective-Function-Formulation for Derringer’s Function based Model Updating Method
Authors: Shankar Sehgal, Harmesh Kumar
Abstract: Objective-function-formulation plays very important role in successfully solving any optimization problem in general and model updating problem in particular. This paper presents detailed investigations on three different types of objective-function-formulations for Derringer’s function based finite element model updating method. Three case studies are considered wherein during first case study the objective-functionformulations are based upon natural frequencies only, while for second case study, only the modal assurance criterion values are used for formulating the objectives. In third case study, a combination of natural frequencies and modal assurance criterion values are used for formulation of objective-functions. The three objective-function-formulations are then compared against each other in terms of error reduction in prediction of response variables as well as physical input parameters. It is established that error reduction is maximum when both natural frequencies and modal assurance criterion values are collectively used for formulation of objective-functions of model updating problem. This benchmark objective-function-formulation is then used further in refined model updating stage so as to increase the chances of obtaining more accurate and reliable updating results significantly.
Keywords: Objective-function-formulation, Finite element model updating, Derringer’s function, Response surface, Analysis of variance
WSEAS Transactions on Applied and Theoretical Mechanics, ISSN / E-ISSN: 1991-8747 / 2224-3429, Volume 9, 2014, Art. #6, pp.60-79
Title of the Paper: Stabilized Least Squares Finite Element Method for 2D and 3D Convection-Diffusion
Authors: V. D. Pereira, J. B. C. Silva, L. F. M. Moura, E. C. Romão
Abstract: In this study, a computational code has been developed based into Finite Elements Method in the version of LSFEM (Least Squares Finite Element Method). The numeric development of this method has as a main advantage, the obtaining of an always symmetrical and defined positive algebraic system, independently of the considered partial-differential equation system. The computational code was applied in the solution of two-dimensional and three-dimensional convection-diffusion problems, through domain discretization of structured meshes of quadratic elements. Obtained numerical results showed a good concordance with available results, showing the developed model validity.
Keywords: Finite Element Method, Least Squares, Convection, Diffusion, Peclet number, Conjugate Gradient Method
WSEAS Transactions on Applied and Theoretical Mechanics, ISSN / E-ISSN: 1991-8747 / 2224-3429, Volume 9, 2014, Art. #5, pp.45-59
Title of the Paper: Thermal Analysis and Test Research of the Magnetic Powder Clutch for Vehicles
Authors: Wang Cheng, Xu Shanzhen, Wu Yonghai
Abstract: The magnetic powder clutch designed for vehicles was taken as the research object to analyze its working ability. The heat source intensity and thermal parameters of the magnetic powder clutch were determined based on thermal analysis theory and the operating state analysis of the magnetic powder clutch under three typical stable conditions. Then the temperature finite element model was established and the temperature distribution and change were analyzed. The feasibility and the working reliability of the designed magnetic powder clutch were evaluated by using the simulation results, which provided evidence for the later research. Finally, the test prototype and test bench of the magnetic powder clutch for vehicle was developed. The test results showed that the temperature field analysis model of magnetic powder clutch established in this paper was accurate and the designed magnetic powder clutch satisfied the requirement for working.
Keywords: magnetic powder clutch, vehicle, temperature field, FEM, simulation, test
WSEAS Transactions on Applied and Theoretical Mechanics, ISSN / E-ISSN: 1991-8747 / 2224-3429, Volume 9, 2014, Art. #4, pp.35-44
Title of the Paper: Initial Imperfections of Steel and Steel-Concrete Composite Columns Subjected to Buckling Compression
Authors: Marcela Karmazínová, Jindrich Melcher
Abstract: The paper deals with the problems of the load-carrying capacity of steel and steel-concrete composite members composed of high-strength materials, subjected to compression. The attention is mainly paid to the buckling resistance in the connection with member imperfections, which are usually covered by the equivalent initial geometrical imperfection expressed as the maximal initial member curving in the mid-length of the buckled member subjected to compression. The paper is oriented to the analytical solution of the initial eccentricity based on the conception of the buckling strength and to the possibilities how to verify the initial imperfection experimentally. The analysis of this problem is shown on the examples of steel and steel-concrete composite columns represented by open HEA cross-section and the same cross-sections partially encased by concrete, and by steel circular tubes and steel tubes filled by concrete, in both cases applying normal-strength and high-strength concrete. Using test results of the specimens subjected to compression the comparison of actual values of initial imperfections with the corresponding theoretical values is presented here.
Keywords: Column buckling, compression, resistance, strength, imperfection, eccentricity, steel, concrete, HEA cross-section, circular cross-section, theoretical analysis, experimental verification, Southwell’s line
WSEAS Transactions on Applied and Theoretical Mechanics, ISSN / E-ISSN: 1991-8747 / 2224-3429, Volume 9, 2014, Art. #3, pp.27-34
Title of the Paper: Structural Dynamic Finite Element Model Updating Using Derringer’s Function: A Novel Technique
Authors: Shankar Sehgal, Harmesh Kumar
Abstract: Aim of this research paper is to develop a new structural dynamic finite element model updating (FEMU) technique using Derringer’s desirability function. Proposed FEMU technique allows formation of subobjectives of model updating problem in a detailed and flexible but in a simplified and user friendly manner. Beauty of the proposed technique is that user can set target value, lower limit, upper limit, weightage on lower limit, weightage on upper limit and relative importance of each sub-objective of model updating problem. Two updating parameters (Elastic modulus and moment of inertia) of a beam structure are varied to develop experimental design matrix. This design matrix is further used to generate response surfaces for first five natural frequencies using response surface methodology. Derringer’s function approach is used for formulating individual desirability function for each sub-objective by considering corresponding natural frequency predicted by response surface model, simulated experimental natural frequency (target value), desired upper and lower limits on predicted frequency, weights on upper and lower limits, and, importance of the related mode (sub-objective). Individual desirability functions are then combined to produce a single overall desirability function, thereby reducing the complex multi-objective FEMU problem to single objective FEMU problem. Optimum (maximum) value of overall desirability function is then used to find out the value of updating parameters. Updating parameters are then used to produce an updated FE model. Dynamic results of updated FE model are then compared with their simulated experimental counterparts and it is found that absolute average error between FE and simulated experimental results is reduced from 14.6% (before updating) to just 0.02% (after updating), thereby suggesting successful implementation of proposed FEMU technique.
Keywords: Structural dynamics, Finite Element, Model updating, Response surface methodology, Derringer’s function
WSEAS Transactions on Applied and Theoretical Mechanics, ISSN / E-ISSN: 1991-8747 / 2224-3429, Volume 9, 2014, Art. #2, pp.11-26
Title of the Paper: Design and Dynamic Simulation Analysis of Flexible Swap Device Based on Pro/E and ADAMS
Authors: Yanbo Cui, Lasheng Zhao, Qiang Zhang, Xiaopeng Wei
Abstract: With the development of space science and technology, on-orbit module replacement technology has been more and more attention. Accordance with the requirements of on-orbit spacecraft module replacement, this paper designs the flexible swap device, and analyses the working principle of the insert-pull process. Using Pro/E, the parametric geometry model is established, whose dynamics simulation analysis is realized by ADAMS. First of all, the principle and validation of motion process is analyzed. Then, the impact on the overall devices is discussed when the collision model is under the different working conditions. In order to meet the requirements of damping force and reduce the vibration of the collision, the buffer parameters are adjusted. In the whole simulation process, the important parameters are measured, and the relation between collision force and the entire system are studied. Finally, the paper provides the reasonable design parameters according to the above analysis.
Keywords: flexible swap device, parameterized geometry model, dynamic simulation analysis
WSEAS Transactions on Applied and Theoretical Mechanics, ISSN / E-ISSN: 1991-8747 / 2224-3429, Volume 9, 2014, Art. #1, pp.1-10
