Journal of Computational & Applied Research in Mechanical Engineering (JCARME)Journal of Computational & Applied Research in Mechanical Engineering (JCARME)
http://jcarme.srttu.edu/
Tue, 25 Jul 2017 19:17:51 +0100FeedCreatorJournal of Computational & Applied Research in Mechanical Engineering (JCARME)
http://jcarme.srttu.edu/
Feed provided by Journal of Computational & Applied Research in Mechanical Engineering (JCARME). Click to visit.contents
http://jcarme.srttu.edu/article_604_120.html
Wed, 31 May 2017 19:30:00 +0100Heat transfer in MHD nanofluid flow over a cone and plate in the presence of heat source/sink
http://jcarme.srttu.edu/article_637_0.html
In this study, we presented a mathematical model for analyzing the heat source/sink effect on magnetohydrodynamic two-dimensional ferrofluid flow past a cone and a vertical plate in the presence of volume fraction of ferrous nanoparticles. The governing partial differential equations are transformed as ordinary differential equations making use of similarity solutions and solved numerically with the aid of Runge-Kutta based shooting technique. The limiting case of the present results shows a good agreement with the published results. We presented solutions for the flow over a cone and a vertical plate cases. The influence of dimensionless parameters on velocity and temperature profiles along with the friction factor coefficient and the heat transfer rate are analyzed with the help of graphs and tables. It is found that the rising value of the volume fraction of ferrous nanoparticles enhances the friction factor coefficient and heat transfer rate. It is also found that heat transfer performance of the flow over a plate is comparatively higher than the flow over a cone.Fri, 14 Jul 2017 19:30:00 +0100Editor in Chief Letter
http://jcarme.srttu.edu/article_605_120.html
Wed, 31 May 2017 19:30:00 +0100On the flexural properties of multiscale nanosilica/E-glass/epoxy anisogrid-stiffened composite ...
http://jcarme.srttu.edu/article_638_0.html
In the present study, multiscale nanosilica/E-glass/epoxy anisogrid composite panels were investigated for flexural properties as a function of nanosilica loading in the matrix (0, 1, 3 and 5 wt.%). The surface of the silica nanoparticles was firstly modified with 3-glycidoxypropyltrimethoxysilane (3-GPTS). The fourier transform infrared (FTIR) spectroscopy revealed that the organic functional groups of the silane were successfully grafted on the surface of the nanoparticles. It was illustrated that flexural properties of the composite panel loaded from the skin side can be significantly enhanced by incorporating silica nanoparticles. The use of 3 wt.% nanosilica was the most effective in increasing the load bearing capacity and energy absorption value, while the specimen containing 5 wt.% nanosilica demonstrated the highest flexural stiffness. From the results obtained for the anisogrid panels loaded from the skin side, it was found that these structures displayed excellent damage resistance which is represented by their energy absorption capability. Moreover, a significant portion of energy absorbed after the primary failure at the peak load. Finally, the results correlated well with the observation of field emission scanning electron microscopy (FESEM) micrographs where the nanocomposite panels exhibited higher degree of fiber-matrix interfacial strength and also enhanced matrix characteristics, imparted by the incorporation of surface modified silica nanoparticles.Fri, 14 Jul 2017 19:30:00 +0100A comparative study between two numerical solutions of the Navier-Stokes equations
http://jcarme.srttu.edu/article_580_120.html
The present study aimed to investigate two numerical solutions of the Navier-Stokes equations. For this purpose, the mentioned flow equations were written in two different formulations, namely (i) velocity-pressure and (ii) vorticity-stream function formulations. Solution algorithms and boundary conditions were presented for both formulations and the efficiency of each formulation was investigated by considering a two-dimensional low laminar flow around a square pile in a rectangular computational domain. Simulations under the same conditions were conducted to assess the difference between results generated by both formulations. Furthermore, the accuracy of the results was analyzed through a comparison of the results with the available reference data. In addition, computational efficiency of both formulations was investigated in term of computation time. The corresponding results indicated that both formulations are adequate to the case used in the present study. Moreover, performed simulations showed that solving the vorticity-stream function form of the flow equations is faster than solving the velocity-pressure form of those equations for simulating a two-dimensional laminar flow around a square pile.Thu, 02 Mar 2017 20:30:00 +0100The Effect of Small Scale and Intermolecular Forces on the Nonlinear Pull-in Instability ...
http://jcarme.srttu.edu/article_639_0.html
Using differential quadrature method (DQM), this study investigated pull-in instability of beam-type nano-switches under the effects of small-scale and intermolecular forces including the van der Waals (vdW) and the Casimir forces. In these nano-switches, electrostatic forces served as the driving force, and von-Karman type nonlinear strain was used to examine nonlinear geometric effects. To derive nonlinear governing equations as well as the related boundary conditions for the nano-beam, variation method was used. Besides, to study the influence of size effect, the nonlocal elasticity theory was employed and the resulting governing equations were solved using DQM. Finally, the pull-in parameters were studied using the nonlocal theory and the results were compared with the numerical results of the classical continuum theory as well as experimental results contained in the references. Results demonstrated that taking into consideration the von-Karman type nonlinear strain increases the beam stiffness and hence, the pull-in voltage. Besides, use of the small scale, compared with the classical theory of elasticity, yields results much closer to experimental results.Fri, 14 Jul 2017 19:30:00 +0100Influence of heat generation on the phase transformations and impact responses of composite ...
http://jcarme.srttu.edu/article_581_120.html
In the present research, in contrast to the available papers, not only the superelasticity but also the shape memory effects are taken into account in determination of the impact responses. At the same time, in addition to modifying Brinson’s model for the shape memory alloys (SMAs), to include new parameters and loading events, and Hertz contact law, distributions of the SMA phases are considered to be both localized and time-dependent. Furthermore, effects of the impact-induced heat generation and mechanical energy on the resulting histories of the martensite phase volume fraction, stress-strain, temperature, lateral deflection, and contact force are investigated. The generated heat in the SMA wires during the impact is determined through using a Helmholtz free energy function including the latent heat of the phase transformation. The resulting governing equations are solved by the finite element method. The nonlinear refined constitutive laws are solved through a return-mapping Newton-Raphson procedure. Results reveal that incorporation of the heat generation effects is significant in medium/high-velocity impacts or when the stress field is almost uniform.Thu, 02 Mar 2017 20:30:00 +0100Evaluation of combined hardening model in ratcheting behavior of pressurized piping elbows ...
http://jcarme.srttu.edu/article_640_0.html
In this paper the ratcheting behavior of carbon steel(ASTM A106B) and stainless steel(304L) elbows is studied under steady internal pressure and in-plane external moments at frequencies typical of seismic excitations. The finite element analysis with the nonlinear isotropic/kinematic (combined) hardening model has been used to evaluate ratcheting behavior of the elbows. Material parameters have been obtained from several stabilized cycles of specimens that are subjected to symmetric strain cycles. The rate of ratcheting depends significantly on the magnitudes of the internal pressure, dynamic bending moment and material constants for combined hardening model. The results show that the maximum ratcheting is occurred in the hoop direction at crown. Also, the results show that initially, the calculated rate of ratcheting is large and then decreases with the increasing of cycles. Also, the results obtained by using the Combined hardening model gives acceptable adaptation in comparison with the other hardening models(AF and Chaboche hardening models); however this model gives over estimated values comparing with the experimental data.Fri, 14 Jul 2017 19:30:00 +0100Chemical reaction and thermal radiation effects on MHD micropolar fluid past a stretching sheet ...
http://jcarme.srttu.edu/article_582_120.html
The paper aims at investigating the effects of chemical reaction and thermal radiation on the steady two-dimensional laminar flow of viscous incompressible electrically conducting micropolar fluid past a stretching surface embedded in a non-Darcian porous medium. The radiative heat flux is assumed to follow Rosseland approximation. The governing equations of momentum, angular momentum, energy, and species equations are solved numerically using Runge-Kutta fourth order method with the shooting technique. The effects of various parameters on the velocity, microrotation, temperature and concentration field as well as skin friction coefficient, Nusselt number and Sherwood number are shown graphically and tabulated. It is observed that the micropolar fluid helps the reduction of drag forces and also acts as a cooling agent. It was found that the skin-friction coefficient, heat transfer rate, and mass transfer rate are decreased, and the gradient of angular velocity increases as the inverse Darcy number, porous medium inertia coefficient, or magnetic field parameter increase. Increases in the heat generation/absorption coefficient caused increases in the skin-friction coefficient and decrease the heat transfer rate. It was noticed that the increase in radiation parameter or Prandtl number caused a decrease in the skin-friction coefficient and an increase in the heat transfer rate. In addition, it was found that the increase in Schmidt number and chemical reaction caused a decrease in the skin-friction coefficient and an increase in the mass transfer rate.Thu, 02 Mar 2017 20:30:00 +0100Free convective heat and mass transfer of magnetic bio-convective flow caused by a rotating ...
http://jcarme.srttu.edu/article_641_0.html
This article explores the heat and mass transfer behaviour of magnetohydrodynamic free convective flow past a permeable vertical rotating cone and a plate filled with gyrotactic microorganisms in the presence of nonlinear thermal radiation, thermo diffusion and diffusion thermo effects. We presented dual solutions for the flow over a rotating cone and a rotating flat plate cases. Similarity variables are employed to convert the nonlinear partial differential equations into ordinary differential equations. Comparisons with previously published work are performed and results are found to be in excellent agreement. The resultant non-dimensional governing equations along with associated boundary conditions are solved numerically using Runge–Kutta and Newton’s methods. The impact of pertinent parameters on velocity, temperature, concentration and density of the motile microorganisms along with the friction factor, local Nusselt, Sherwood numbers and the local density of the motile microorganisms was determined and analyzed with the help of graphs and tables. Results proved that there is a significant variation of heat and mass transfer in the flow over a rotating cone and a plate. It is also found that the heat and mass transfer performance of the flow over a rotating cone is significantly high when compared with the flow over a rotating plate.Fri, 14 Jul 2017 19:30:00 +0100Prediction of earing in deep drawing of anisotropic aluminum alloy sheet using BBC2003 yield ...
http://jcarme.srttu.edu/article_583_120.html
This paper investigates the earing phenomenon in deep drawing of AA3105 aluminum alloy, experimentally and numerically. Earing defect is mainly attributed to the plastic anisotropy of sheet metal. In order to control such defect, predicting the evolution of ears in sheet metal forming analyses becomes indispensable. In this regard, the present study implements the advanced yield criterion BBC2003. Based on this yield function and the associated flow rule of plasticity, the constitutive model is derived. Accordingly, a user material VUMAT subroutine is developed and adopted in the commercial finite element software ABAQUS/Explicit. Several plane stress loading problems are designed, through which, the accuracy of the developed subroutine is verified. In addition, cylindrical cups of AA3105 aluminum alloy are fabricated using a deep drawing die. The earing defect was clearly observed on the recovered parts. Using the experimentally obtained constants of BBC2003 yield criterion for this alloy in VUMAT, deep drawing of the cylindrical cups was simulated. The results demonstrate that the earing profile can successfully be predicted using BBC2003 yield function.Thu, 02 Mar 2017 20:30:00 +0100An efficient analytical solution for nonlinear vibrations of a parametrically excited beam
http://jcarme.srttu.edu/article_642_0.html
An efficient and accurate analytical solution is provided using the homotopy-Pade technique for the nonlinear vibration of parametrically excited cantilever beams. The model is based on the Euler-Bernoulli assumption and includes third order nonlinear terms arisen from the inertial and curvature nonlinearities. The Galerkin’s method is used to convert the equation of motion to a nonlinear ordinary differential equation, which is then solved by the homotopy analysis method (HAM). An explicit expression is obtained for the nonlinear frequency amplitude relation. It is found that the proper value of the so-called auxiliary parameter for the HAM solution is dependent on the vibration amplitude, making it difficult to rapidly obtain accurate frequency-amplitude curves using a single value of the auxiliary parameter. The homotopy-Pade technique remedied this issue by leading to the approximation that is almost independent of the auxiliary parameter and is also more accurate than the conventional HAM. Highly accurate results are found with only third order approximation for a wide range of vibration amplitudes.Fri, 14 Jul 2017 19:30:00 +0100Assessment of different methods for fatigue life prediction of steel in rotating bending and ...
http://jcarme.srttu.edu/article_597_120.html
Generally, fatigue failure in an element happens at the notch on a surface where the stress level rises because of the stress concentration effect. The present paper investigates the effect of a notch on the fatigue life of the HSLA100 (­high strength low alloy) steel which is widely applicable in the marine industry. Tensile test was conducted on specimens and mechanical properties were obtained. Rotating bending and axial fatigue tests were performed at room temperature on smooth and notched specimens and S-N curves were obtained. Using the obtained S-N curve for smooth specimens, the fatigue strength factor for the notched specimens were predicted by Weibull's weakest-link, ­Peterson, Neuber, stress gradient and critical distance methods and compared with experimental results. It was found that the critical distance and also Weibull’s weakest-link methods have the best agreement with experimental results.Thu, 02 Mar 2017 20:30:00 +0100Water hammer simulation by explicit central finite difference methods in staggered grids
http://jcarme.srttu.edu/article_598_120.html
Four explicit finite difference schemes, including Lax-Friedrichs, Nessyahu-Tadmor, Lax-Wendroff and Lax-Wendroff with a nonlinear filter are applied to solve water hammer equations. The schemes solve the equations in a reservoir-pipe-valve with an instantaneous and gradual closure of the valve boundary. The computational results are compared with those of the method of characteristics (MOC), and with the results of Godunov''s scheme to verify the proposed numerical solution. The computations reveal that the proposed Lax-Friedrichs and Nessyahu-Tadmor schemes can predict the discontinuities in fluid pressure with an acceptable order of accuracy in cases of instantaneous and gradual closure. However, Lax-Wendroff and Lax-Wendroff with nonlinear filter schemes fail to predict the pressure discontinuities in instantaneous closure. The independency of time and space steps in these schemes are allowed to set different spatial grid size with a unique time step, thus increasing the efficiency with respect to the conventional MOC. In these schemes, no Riemann problems are solved; hence field-by-field decompositions are avoided. As provided in the results, this leads to reduced run times compared to the Godunov scheme.Thu, 02 Mar 2017 20:30:00 +0100Dynamical formation control of wheeled mobile robots based on fuzzy logic
http://jcarme.srttu.edu/article_600_120.html
In this paper, the important formation control problem of nonholonomic wheeled mobile robots is investigated via a leader-follower strategy. To this end, the dynamics model of the considered wheeled mobile robot is derived using Lagrange equations of motion. Then, using ADAMS multi-body simulation software, the obtained dynamics of the wheeled system in MATLAB software is verified. After that, in order to generate and keep the desired formation, a Fuzzy Logic Controller is designed. In this regard, the leader mobile robot is controlled to follow a reference path and the follower robots use the Fuzzy Logic Controller to keep constant relative distance and constant angle with respect to the leader. The efficiency of the suggested dynamics-based formation controller has been proved using several computer simulations under different situations and desired trajectories. Also, the performance of the follower robot in path tracking is checked in the presence of receiving noisy data from the leader robot.Thu, 02 Mar 2017 20:30:00 +0100An efficient finite difference time domain algorithm for band structure calculations of ...
http://jcarme.srttu.edu/article_601_120.html
In this paper, a new algorithm for studying elastic wave propagation in the phononic crystals is presented. At first, the displacement-based forms of elastic wave equations are derived and then the forms are discretized using finite difference method. So the new algorithm is called the displacement-based finite difference time domain (DBFDTD). Three numerical examples are computed with this method and the results are compared with experimental measurements and the conventional FDTD method. Also, the computational cost of the new approach is compared with the conventional FDTD method. The comparison showed that the calculation time of the DBFDTD method is 37.5 percent less than that of the FDTD method.Thu, 02 Mar 2017 20:30:00 +0100Vibration analysis of functionally graded cylindrical shells with different boundary conditions ...
http://jcarme.srttu.edu/article_602_120.html
In the present work, study of the vibration of a functionally graded (FG) cylindrical shell made up of stainless steel, zirconia, and nickel is presented. Free vibration analysis is presented for FG cylindrical shells with simply supported-simply supported and clamped–clamped boundary condition based on temperature independent material properties. The equations of motion are derived by Hamilton’s principle. Material properties assume to be graded in the thickness direction according to a simple power law distribution in terms of the volume fraction of the constituents. Effects of boundary conditions and volume fractions (power law exponent) on the natural frequencies of the FG cylindrical shell are studied. Frequency characteristics of the FG shell are found to be similar to those of isotropic cylindrical shells. Furthermore, natural frequencies of these shells are observed to be dependent on the constituent volume fractions and boundary conditions. Strain displacement relations from Love's and first-order shear deformation theories are employed. Galerkin method is used to derive the governing equations for clamped boundary conditions. Further, analytical results are validated with those reported in the literature and excellent agreement is observed. Finally, in order to investigate the effects of the temperature gradient, functionally graded materials cylindrical shell with high temperature specified on the inner surface and outer surface at ambient temperature,1D heat conduction equation along the thickness of the shell is applied and the results are reported.Thu, 02 Mar 2017 20:30:00 +0100Enhancing the low cycle fatigue strength of AA6061 aluminum alloy by using the optimized ...
http://jcarme.srttu.edu/article_603_120.html
In the present study, mechanical properties and low cycle fatigue behavior of a solid-solutionized AA6061 aluminum alloy produced by equal channel angular pressing (ECAP) process were investigated. The grain refinement after two passes of ECAP significantly increased the yield stress and ultimate tensile stress and decreased the ductility of the alloy. However, the improvement of low cycle fatigue strength was not as remarkable as expected. Post-ECAP aging heat treatment to the peak-aging condition imposed a notable change in the strength and ductility of the alloy so that its fatigue strength partly enhanced. An optimized combination of grain refinement and distributed fine precipitates in the matrix of the alloy was achieved by conducting aging heat treatment between passes of ECAP. The proposed procedure was proved to yield the best combination of strength and ductility, better distribution and size of precipitates, and thus a remarkable improvement in the low cycle fatigue response of the investigated material.Thu, 02 Mar 2017 20:30:00 +0100