Abstract: Nondestructive deflection testing has been accepted widely as a cost-effective tool for evaluating the structural condition of airfield pavements. Backcalculation of pavement layer moduli can be used to characterize the pavement existing condition in order to compute the load bearing capacity of pavement. This paper presents an improved best-fit backcalculation methodology based on deflection predictions obtained using finite element method (FEM). The best-fit approach is based on minimizing the squared error between falling weight deflectometer (FWD) measured deflections and FEM predicted deflections. Then, concrete elastic modulus and modulus of subgrade reaction were back-calculated using Heavy Weight Deflectometer (HWD) deflections collected at the National Airport Pavement Testing Facility (NAPTF) test site. It is an alternative and more versatile method in considering concrete slab geometry and HWD testing locations compared to methods currently available.
Abstract: Previously, some materials like solid metals and their alloys have been used as implants in human’s body. In order to amend fixation of these artificial hard human tissues, some porous structures have been introduced. In this way, tissues in vicinity of the porous structure can be attached more easily to the inserted implant. In particular, the porous bone scaffolds are useful since they can deliver important biomolecules like growth factors and proteins. This study focuses on the properties of the degradable porous hard tissues using a three-dimensional numerical Finite Element Method (FEM). The most important studied properties of these structures are diffusivity flux and concentration of different species like glucose, oxygen, and lactate. The process of cells migration into the scaffold is considered as a diffusion process, and related parameters are studied for different values of production/consumption rates.
Abstract: In this work, efficient directional coupler composed of
dielectric waveguides and metallic film has been analyzed in details
by simulations using finite element method (FEM). The structure
consists of a step-index fiber with dielectric core, silica cladding, and
a metal nanowire parallel to the core. The results show that an
efficient conversion of optical dielectric modes to long range
plasmonic is possible. Low insertion losses in conjunction with short
coupling length and a broadband operation can be achieved under
certain conditions. This kind of couplers has potential applications for
the design of photonic integrated circuits for signal routing between
dielectric/plasmonic waveguides, sensing, lithography, and optical
storage systems. A high efficient focusing of light in a very small
region can be obtained.
Abstract: In the laser cleavage of glass, the laser is mostly adopted as a heat source to generate a thermal stress state on the substrates. The crack propagation of the soda-lime glass in the laser thermal cleavage with the straight-turning paths was investigated in this study experimentally and numerically. The crack propagation was visualized by a high speed camera with the off-line examination on the micro-crack propagation. The temperature and stress distributions induced by the laser heat source were calculated by ANSYS software based on the finite element method (FEM). With the cutting paths in various turning directions, the experimental and numerical results were in comparison and verified. The fracture modes due to the normal and shear stresses were verified at the turning point of the laser cleavage path. It shows a significant variation of the stress profiles along the straight-turning paths and causes a change on the fracture modes.
Abstract: Cab’s frame strength is considered as an important factor in excavator’s operator safety, especially during roll-over. In this study, we use a model of cab frame with different thicknesses and perform elastoplastic numerical analysis by using Finite Element Method (FEM). Deformation mode and energy absorption's of cab’s frame part are investigated on two conditions, with wrinkle and without wrinkle. The occurrence of wrinkle when deforming cab frame can reduce energy absorption, and among 4 parts with wrinkle, the energy absorption significantly decreases in part C. Residual stress that generated upon the bending process of part C is analyzed to confirm it possibility in increasing the energy absorption.
Abstract: Microcantilevers are the basic MEMS devices, which
can be used as sensors, actuators and electronics can be easily built
into them. The detection principle of microcantilever sensors is based
on the measurement of change in cantilever deflection or change in its
resonance frequency. The objective of this work is to explore the
analogies between mechanical and electrical equivalent of
microcantilever beams. Normally scientists and engineers working in
MEMS use expensive software like CoventorWare, IntelliSuite,
ANSYS/Multiphysics etc. This paper indicates the need of developing
electrical equivalent of the MEMS structure and with that, one can
have a better insight on important parameters, and their interrelation of
the MEMS structure. In this work, considering the mechanical model
of microcantilever, equivalent electrical circuit is drawn and using
force-voltage analogy, it is analyzed with circuit simulation software.
By doing so, one can gain access to powerful set of intellectual tools
that have been developed for understanding electrical circuits Later
the analysis is performed using ANSYS/Multiphysics - software based
on finite element method (FEM). It is observed that both mechanical
and electrical domain results for a rectangular microcantlevers are in
agreement with each other.
Abstract: The characteristics of temperature distribution and
electric field in a natural rubber glove (NRG) using microwave
energy during microwave heating process are investigated
numerically and experimentally. A three-dimensional model of NRG
and microwave oven are considered in this work. The influences of
position, heating time and rotation angle of NRG on temperature
distribution and electric field are presented in details. The coupled
equations of electromagnetic wave propagation and heat transfer are
solved using the finite element method (FEM). The numerical model
is validated with an experimental study at a frequency of 2.45 GHz.
The results show that the numerical results closely match the
experimental results. Furthermore, it is found that the temperature
distribution and electric field increases with increasing heating time.
The hot spot zone appears in NRG at the tip of middle finger while
the maximum temperature occurs in case of rotation angle of NRG =
60 degree. This investigation provides the essential aspects for a
fundamental understanding of heat transport of NRG using
microwave energy in industry.
Abstract: This paper discuss a coupling strategy of two different
software packages to provide fluid structure interaction (FSI) analysis.
The basic idea is to combine the advantages of the two codes
to create a powerful FSI solver for two and three dimensional
analysis. The fluid part is computed by a program called PETSc-FEM
a software developed at Centro de Investigaci´on de M´etodos
Computacionales –CIMEC. The structural part of the coupled process
is computed by the research code elementary Parallel Solver –
(ELPASO) of the Technische Universit¨at Braunschweig, Institut f¨ur
Konstruktionstechnik (IK).
Abstract: This paper interested in the mechanical deformation behavior of shear deformable functionally graded ceramic-metal (FGM) plates. Theoretical formulations are based on power law theory when build up functional graded material. The mechanical properties of the plate are graded in the thickness direction according to a power-law Displacement and stress is obtained using finite element method (FEM). The load is supposed to be a uniform distribution over the plate surface (XY plane) and varied in the thickness direction only. An FGM’s gradation in material properties allows the designer to tailor material response to meet design criteria. An FGM made of ceramic and metal can provide the thermal protection and load carrying capability in one material thus eliminating the problem of thermo-mechanical deformation behavior. This thesis will explore analysis of FGM flat plates and shell panels, and their applications to r structural problems. FGMs are first characterized as flat plates under pressure in order to understand the effect variation of material properties has on structural response. In addition, results are compared to published results in order to show the accuracy of modeling FGMs using ABAQUS software.
Abstract: The aim of the current work is to present a comparison among three popular optimization methods in the inverse elastostatics problem (IESP) of flaw detection within a solid. In more details, the performance of a simulated annealing, a Hooke & Jeeves and a sequential quadratic programming algorithm was studied in the test case of one circular flaw in a plate solved by both the boundary element (BEM) and the finite element method (FEM). The proposed optimization methods use a cost function that utilizes the displacements of the static response. The methods were ranked according to the required number of iterations to converge and to their ability to locate the global optimum. Hence, a clear impression regarding the performance of the aforementioned algorithms in flaw identification problems was obtained. Furthermore, the coupling of BEM or FEM with these optimization methods was investigated in order to track differences in their performance.
Abstract: In this study, the hydrogen transport phenomenon was
numerically evaluated by using hydrogen-enhanced localized
plasticity (HELP) mechanisms. Two dominant governing equations,
namely, the hydrogen transport model and the elasto-plastic model,
were introduced. In addition, the implicitly formulated equations of
the governing equations were implemented into ABAQUS UMAT
user-defined subroutines. The simulation results were compared to
published results to validate the proposed method.
Abstract: Today with the rapid growth of telecommunications equipment, electronic and developing more and more networks of power, influence of electromagnetic waves on one another has become hot topic discussions. So in this article, this issue and appropriate mechanisms for EMC operations have been presented. First, a source of alternating current (50 Hz) and a clear victim in a certain distance from the source is placed. With this simple model, the effects of electromagnetic radiation from the source to the victim will be investigated and several methods to reduce these effects have been presented. Therefore passive and active shields have been used. In some steps, shielding effectiveness of proposed shields will be compared. . It should be noted that simulations have been done by the finite element method (FEM).
Abstract: –In this paper the damage in clamped-free, clampedclamped and free-free beam are analyzed considering samples
without and with structural modifications. The damage location is
investigated by the use of the bispectrum and wavelet analysis. The
mathematical models are obtained using 2D elasticity theory and the
Finite Element Method (FEM). The numerical and experimental data
are approximated using the Particle Swarm Optimizer (PSO) method
and this way is possible to adjust the localization and the severity of
the damage. The experimental data are obtained through
accelerometers placed along the sample. The system is excited using
impact hammer.
Abstract: This paper deals with the thermo-mechanical deformation behavior of shear deformable functionally graded ceramicmetal (FGM) plates. Theoretical formulations are based on higher order shear deformation theory with a considerable amendment in the transverse displacement using finite element method (FEM). The mechanical properties of the plate are assumed to be temperaturedependent and graded in the thickness direction according to a powerlaw distribution in terms of the volume fractions of the constituents. The temperature field is supposed to be a uniform distribution over the plate surface (XY plane) and varied in the thickness direction only. The fundamental equations for the FGM plates are obtained using variational approach by considering traction free boundary conditions on the top and bottom faces of the plate. A C0 continuous isoparametric Lagrangian finite element with thirteen degrees of freedom per node have been employed to accomplish the results. Convergence and comparison studies have been performed to demonstrate the efficiency of the present model. The numerical results are obtained for different thickness ratios, aspect ratios, volume fraction index and temperature rise with different loading and boundary conditions. Numerical results for the FGM plates are provided in dimensionless tabular and graphical forms. The results proclaim that the temperature field and the gradient in the material properties have significant role on the thermo-mechanical deformation behavior of the FGM plates.
Abstract: This paper presents an approach which is based on the
use of supervised feed forward neural network, namely multilayer
perceptron (MLP) neural network and finite element method (FEM)
to solve the inverse problem of parameters identification. The
approach is used to identify unknown parameters of ferromagnetic
materials. The methodology used in this study consists in the
simulation of a large number of parameters in a material under test,
using the finite element method (FEM). Both variations in relative
magnetic permeability and electrical conductivity of the material
under test are considered. Then, the obtained results are used to
generate a set of vectors for the training of MLP neural network.
Finally, the obtained neural network is used to evaluate a group of
new materials, simulated by the FEM, but not belonging to the
original dataset. Noisy data, added to the probe measurements is used
to enhance the robustness of the method. The reached results
demonstrate the efficiency of the proposed approach, and encourage
future works on this subject.
Abstract: Today with the rapid growth of telecommunications equipment, electronic and developing more and more networks of power, influence of electromagnetic waves on one another has become hot topic discussions. So in this article, this issue and appropriate mechanisms for EMC operations have been presented. First, impact of high voltage lines on the surrounding environment especially on the control room has been investigated, then to reduce electromagnetic radiation, various methods of shielding are provided and shielding effectiveness of them has been compared. It should be expressed that simulations have been done by the finite element method (FEM).
Abstract: In this paper presented initial design of Low Speed
Axial Flux Permanent Magnet (AFPM) Machine with Non-Slotted
TORUS topology type by use of certain algorithm (Appendix).
Validation of design algorithm studied by means of selected data of
an initial prototype machine. Analytically design calculation carried
out by means of design algorithm and obtained results compared with
results of Finite Element Method (FEM).