Journal of Applied and Computational Mechanics
Volume:8 Issue: 1, Winter 2022

Medium density fiberboard (MDF) is an engineering product that is used in many industrial and general applications such as the furniture industry and kitchen cabinets. Generally, MDF products are generated by screw joints using the drilling process. However, the drilling process of the MDF panels leads to the delamination at the entrance and exit of the drill bit that should be controlled. In this work, the effect of the processing parameters including the feed rate and cutting speed on the delamination of melamine coated MDF is investigated. For this, two different tools with different tool geometry (a brad point drill bit and a commonly used twist drill bit) are examined. Image processing is used to measure the conventional delamination factor together with a new delamination factor referred to as area delamination factor for the drilled holes. It that the delamination value decreases with increasing cutting speed and increases with increasing feed rate. Though, there were some fluctuations in the results. The trend of changing the delamination respect to the investigated parameters was the same for both applied drill bits; however, the smaller value of delamination is obtained using the twist drill bit. Using the proposed area delamination factor, the effect of process parameters on the delamination is presented with higher magnitudes but with the same behavior. This, together with the ability of characterization of the water absorption of drilled holes has made the area delamination factor a more appropriate parameter to evaluate the delamination. The overall results are consistent with previously published works.

The purpose of this study is to present simulation and numerical solutions to the unsteady flow and heat transfer near stagnation point over a stretching/shrinking sheet in porous medium filled with a hybrid nanofluid. Water (base fluid), nanoparticles of titania and copper were considered as a hybrid nanofluid. It is worth mentioning that evaluating the heat transfer enhancement due to the use of hybrid nanofluids has recently become the center of interest for many researchers. The coupled non-linear boundary-layer equations governing the flow and heat transfer are derived and reduced to a set of coupled non-dimensional equations using the appropriate transformations and then solved numerically as a nonlinear boundary value problem by bvp4c scheme from MATLAB. To validate the modeling of hybrid nanofluid and also numerical procedure, the value of the skin friction and the heat transfer rate for the limited cases of pure water, titania/water and copper/water is obtained and compared with previously reported results that demonstrate an excellent agreement. In the present investigation, the thermal characteristics of hybrid nanofluid are found to be higher in comparison to the base fluid and fluid containing single nanoparticles, respectively. It can be concluded that both skin friction coefficient and local Nusselt number enhance almost linearly with increasing the copper nanoparticle volume fraction (as second nanoparticle). Besides, the porosity and the magnetic effect amplify heat transfer rate, while the unsteadiness parameter has a reducing effect on heat transfer rate in problem conditions.

Nowadays, the preparation, characterization, and modeling of nanofluids are deliberated in plenty to improve the heat transfer effects. Therefore, this paper centers on the heat transfer effects of three separate hybrid nanoparticles such as Al2O3-SiO2, Al2O3-TiO2, and TiO2-SiO2 with a base fluid such as water to gratify the advances. Analytical investigations for the Marangoni convection of different hybrid nanofluids over the flat surface for the cases such as suction, injection and impermeable were analyzed. A validation table for the comparison between analytical and numerical studies is tabulated. The influence of the hybrid nanoparticles solid volume fraction and the wall mass transfer parameter are mentioned through graphs at the side of the heat transfer rate tabulation. The impact of solid volume fraction decelerates the velocity distribution and raises the temperature distribution for all the three hybrid nanofluids in the cases of suction, impermeable, and injection. While relating the surface velocity and heat transfer rate of the three hybrid nanofluids, Al2O3-SiO2/water has a higher surface velocity, TiO2-SiO2/water has a higher heat transfer rate and Al2O3-TiO2/water has lower surface velocity and heat transfer rate for the increment of wall mass transfer parameter.

The friction stir welding method is one of the solid-state welding methods for non-homogeneous metals. In this study, the 5XXX series aluminum sample and pure copper are subjected to four passes friction welding process and then the mechanical and metallurgical properties of the welded samples are compared with the prototype. For this purpose, the effect of welding parameters including rotational speed, forward speed and pin angle of the tool is tested by the full factorial method. In this process, hardness estimation and tensile testing are based on input process parameters in order to obtain mechanical properties is an important issue. For this purpose, a mathematical model of mechanical properties must be defined based on the input process parameters. Due to the complex nature of the effect of input process parameters on mechanical properties, this modeling is a complex mathematical problem in which the use of supervised learning algorithms is considered as an efficient alternative. In this paper, a new combination of Relevance Vector Machine (RVM) and Support Vector Machine (SVM) is presented which has a higher degree of accuracy.

In this article, numerical study of nanofluid flow between two inclined planes is carried out under the influence of magnetic field. Water-based nanofluid with nanoparticle of Copper (Cu) is taken into consideration for the present investigation. An efficient numerical method namely Optimal Homotopy Analysis Method (OHAM) is employed to get an approximate series solution for the related governing differential equation. A new approach is proposed to determine the convergence controller parameters used in OHAM. For the validation of the proposed technique, the convergence of the obtained results is shown for different values of involved parameters. Moreover, residual errors for the different number of terms in the obtained series solution are represented graphically. Obtained numerical results from the proposed method are incorporated with the previous results and they are found to be in very good agreement. Impacts of involved parameters like nanoparticle volume fraction, Hartmann number and Reynolds number on non-dimensional velocity are also discussed.

In this study, the features of Maxwell fluid flow through a stretching sheet (variable thickness) with heat source/sink and melting heat transfer are analyzed. Leading equations of the course are transmuted with suitable similarity transmutations and resolved the subsequent equations mathematically with shooting technique. The effects of the valid parameters on the regular profiles (velocity, concentration, temperature) are elucidated through graphs in two cases (presence and absence of melting). And also, friction factor, transfer rates (mass, heat) are examined with the same parameters and the outcomes are presented in tabular form. A few of the findings are (a) the elastic parameter upsurges the velocity (b) heat source parameter raises the temperature (c) mass transfer rate is lowered by chemical reaction.

In 2008, a technique was proposed to reduce run-times in analysis of semi-discretized equation of motion against dynamic excitations available in digitized format. Later, the technique was successfully adapted to reduce numbers of degrees of freedom in finite element analysis of assemblies of beam-columns subjected to static digitized loads. In this paper, attention is paid to dynamic finite element analysis of assemblies of beam-columns. It is shown that, when the mass is available in digitized format, after small modifications in the original technique, the adaptation can simplify the analysis, regardless of the models' sizes, their linearity or non-linearity, and whether the damping is classical or non-classical. The reductions in run-time and in-core memory are considerable, while the changes in accuracy can be negligible.

In this work, we obtained the numerical solution for the system of nonlinear time-fractional order advection-reaction-diffusion equation using the homotopy perturbation method using Laplace transform method with fractional order derivatives in Liouville-Caputo sense. The solution obtained is very useful and significant to analyze many physical phenomenons. The present technique demonstrates the coupling of homotopy perturbation method and the Laplace transform technique using He’s polynomials, which can be applied to numerous coupled systems of nonlinear fractional models to find the approximate numerical solutions. The salient features of the present work is the graphical presentations of the numerical solution of the concerned nonlinear coupled equation for several particular cases and showcasing the effect of reaction terms on the nature of solute concentration of the considered mathematical model for different particular cases. To validate the reliability, efficiency and accuracy of the proposed efficient scheme, a comparison of numerical solutions and exact solution are reported for Burgers’ coupled equations and other particular cases of concerned nonlinear coupled systems. Here we find high consistency and compatibility between exact and numerical solution to a high accuracy. Presentation of absolute errors for given examples are reported in tabulated and graphical forms that ensure the convergence rate of the numerical scheme.

In this paper, the effect of the bimorph profile on the nonlinear dynamic behavior and performance of a vibratory piezomagnetoelastic energy harvester is investigated. The proposed model is composed of upper and lower piezoelectric layers on a trapezoidal cantilever beam with one attached tip magnet as well as two external magnets. The magnetic field of two external magnets generates magnetic forces and moment on the tip magnet. The bimorph structure is considered as a distributed-parameter system, and the external forces are obtained by analyzing the magnetic field of the external magnets. Equations of motion are obtained using electromagnetic Lagrange equations based on the generalized Hamilton principle and the Euler-Bernoulli beam theory. The proposed model for the bimorph and magnetic forces is validated by previously published experimental results. In order to compare the nonlinear behavior of the rectangular and trapezoidal beam profiles, the bifurcation diagrams are depicted for various control parameters such as the separation distances of the magnets, beam root width, and beam tip width. Verification of the bifurcation diagrams is performed by the phase plane portraits and Poincare maps. Also, the harvested power level is compared for different profiles of the bimorph. Moreover, the simultaneous effects of exciting frequency and bifurcation parameters on the system performance are investigated by the waterfall diagrams. The obtained results show that the trapezoidal beam profile with a lower tip width has higher performance than the rectangular beam. In trapezoidal beam profiles, the subharmonic and chaotic motions have relatively higher output powers than periodic motions.

In this study, the effect of stationary and oscillating blades on the forced convection heat transfer in a channel is studied numerically. Simulations are performed in a fully-developed, laminar, unsteady, and incompressible flow with Reynolds number and Prandtl number equal to 100 and 1, respectively. The effects of the blade geometry, oscillating speed and oscillation angle on heat transfer and pressure drop are studied. The results are presented in terms of time-averaged Nusselt number, temperature, and vorticity distribution and the pressure drop. The results indicate that the oscillation angle, oscillating speed of the blade, and the number of the blades, affect the thermal performance of the channel. In most cases, it is observed that the effect of the oscillation angle is more than that for the oscillating speed on heat transfer enhancement. However, increasing the number of blades does not necessarily help to enhance the heat transfer, but it can slightly decrease the pressure drop.

In this article, the vibration and buckling of a double-layer Graphene sheet (DLGS) coupled with a piezoelectric nanoplate through an elastic medium (Pasternak and Winkler models) are investigated. DLGS are subjected to biaxial in-plane forces and van der Waals force existing between each layer. Polyvinylidene fluoride (PVDF) piezoelectric nanoplate is subjected to an external electric potential. For the sake of this study, sinusoidal shear deformation theory of orthotropic plate expanded with Eringen’s nonlocal theory is selected. The results indicate that nondimensional frequency and nondimensional critical buckling load rise when the ratio of width to thickness increases. Furthermore, incrementing the effect of elastic medium parameter results in increasing the stiffness of the system and, consequently, rising nondimensional frequency and critical buckling load.

Several applications of computational science and engineering, including population dynamics, optimal control, and physics, reduce to the study of a system of second-order boundary value problems. To achieve the improved solution of these problems, an efficient numerical method is developed by using spline functions. A non-polynomial cubic spline-based method is proposed for the first time to solve a linear system of second-order differential equations. Convergence and stability of the proposed method are also investigated. A mathematical procedure is described in detail, and several examples are solved with numerical and graphical illustrations. It is shown that our method yields improved results when compared to the results available in the literature.

In this paper, a literature review on two-wheeled vehicle systems is methodically performed and presented. For this purpose, the principal aspects concerning the kinematic, dynamic, control, and identification features of articulated mechanical systems described within the multibody formulation approach are emphasized in this review article. First, the scientific investigations on two-wheeled vehicle modelling are chronologically described employing a historical literature review approach. This is done to set a consistent context for the subsequent developments analyzed in the paper. Then, following the systematic literature review methodology described in this work, a rich corpus of relevant documents in the time span between 2013-present. Moreover, bibliometric methods are used to construct the conceptual structure map of the research field, which also allowed for formulating a thematic classification. Thus, considering the full-texts of the identified corpus of documents, this work presents a synthetic analysis of the fundamental issues about the multibody approaches for modelling two-wheeled vehicles. Finally, future research perspectives are pointed out in this article

Dynamic instability behavior of functionally graded carbon nanotube reinforced hybrid composite plates subjected to periodic loadings is studied. The governing equations of motion of Mathieu-type are established by using the Galerkin method with reduced eigenfunctions transforms. With the Mathieu equations, the dynamic instability regions of hybrid nanocomposite plates are determined by using the Bolotin’s method. Results reveal that the dynamic instability is significantly affected by the carbon nanotube volume fraction, layer thickness ratio, bending stress, static and dynamic load parameters. The effects of important parameters on the instability region and dynamic instability index of hybrid nanocomposite plates are discussed.

In this paper, two numerical methods for solving the MSEIR model are presented. In constructing these methods, the non-standard finite difference strategy is used. The new methods preserve the qualitative properties of the solution, such as positivity, conservation law, and boundedness. Numerical results are presented to express the efficiency of the new methods.

Motivated by exploring the near-wall transport phenomena involved in bioconvection fuel cells combined with electrically conducting nanofluids, in the present article, a detailed analytical treatment using homotopy analysis method (HAM) is presented of non-similar bioconvection flow of a nanofluid under the influence of magnetic field (Lorentz force) and gyrotactic microorganisms. The flow is induced by a stretching sheet under the action of an oblique magnetic field. In addition, nonlinear radiation effects are considered which are representative of solar flux in green fuel cells. A second thermodynamic law analysis has also been carried out for the present study to examine entropy generation (irreversibility) minimization. The influence of magnetic parameter, radiation parameter and bioconvection Rayleigh number on skin friction coefficient, Nusselt number, micro-organism flux and entropy generation number (EGN) is visualized graphically with detailed interpretation. Validation of the HAM solutions with published results is also included for the non-magnetic case in the absence of bioconvection and nanofluid effects. The computations show that the flow is decelerated with increasing magnetic body force parameter and bioconvection Rayleigh number whereas it is accelerated with stronger radiation parameter. EGN is boosted with increasing Reynolds number, radiation parameter and Prandtl number whereas it is reduced with increasing inclination of magnetic field.

Heat transfer of fluids plays an important role in process flows, as this has significant impacts in process configurations, energy pricing and utilization. Therefore, this paper, the heat and mass transfer of a radiating non-Newtonian Sodium alginate transported through parallel squeezing plates is examined. The radiating-squeezing fluid flows through the parallel plates arranged vertically against each other with multi walled carbon nanotube (MWCNT) particles. Transport mechanics and thermal conditions of the Sodium alginate is studied using systems of coupled nonlinear models. This higher order, governing ordinary differential models are used to analyze the thermal and mass transfer of the nanofluid using the adomian decomposition method. Results obtained from analytical study displayed graphically are used to investigate effect of thermal radiation on film flow of MWCNT nanoparticles on the Sodium alginate. As revealed from result, concentration increase of MWCNT nanoparticles increases thermal profile significantly. This can be physically explained owing to increasing concentration, increases thickness of thermal boundary due to conductivity enhancement of fluid. Improved thermal diffusivity drops thermal gradient which reduces heat transfer. Whereas, radiation effect on fluid transport shows decrease in heat transfer as thermal conductivity becomes lower than temperature gradient of the flow. Obtained analysis when compared against other methods of solution (numerical and approximate analytical) proves satisfactory. Therefore, the results obtained from the work provides a good basis for the application and improvement of the Sodium alginate in medical, pharmaceutical and manufacturing industries among other practical application.

In this study, an automatic GNU Octave code, a free high-level language, for the educational purposes was developed to derive equations of motion and constrain equations of a multibody closed chain system and to calculate the response of the system. The code for calculating the dynamic response was developed by formulating several equations in symbolic expression and extracting differential-algebraic equations in matrix form. The code has a similar structure to the previous code for the open chained system, but it deals with the constraint equation and different numerical integration. The examples of closed chain systems provide an additional procedure to derive the constraint equations by using Lagrangian multiplication theory and to solve the differential-algebraic equations using the Runge-Kutta method. The code was made to understand the theory of analysis and the structure of calculation easily. In addition, the code has an automatic process of the derivation of the Lagrange equation and the constraint equations in matrix form after inputting the number of symbolic information such as position and velocity coordinates and design variables of the system that the user wants to review. The code was validated by comparing the dynamic response of the four-bar linkage with the same design variables and initial conditions of the previous work. By using the code, the reader's ability to exchange information such as symbols and matrices will be expected to be improved.

This work is focused on the formulation of a numerical model for prediction of flow field inside a particulate filter. More specifically, a one-dimensional mathematical model of the gas flow in a particulate trap-cell is deduced and solved numerically. The results are given in terms of velocity, pressure, and filtration velocity. In addition, the dependence of the pressure drop on the main governing parameters has been investigated. More specifically, the permeability of the porous medium and the hydraulic diameter play a fundamental role in the pressure drop.

This paper describes the computational aspects of the beam Finite Element formulation recently developed by the authors to simulate the nonlinear response of structural members subjected to shear and torsion, accounting for cross-section warping. The paper focuses on an efficient consistent solution algorithm that by-passes the iterative procedure required in force-based and mixed Finite Elements and makes the model easy to be implemented in a standard code. Moreover, it proposes a new non-iterative technique to condense out the stress components derived by the three-dimensional constitutive response and not directly included in the fiber section formulation. The efficiency and accuracy of the proposed numerical model are validated by simulating the response of steel and reinforced concrete structural members.

In the present study, fluid flow, heat transfer, and entropy generation for mixed convection inside a water-filled square cavity were investigated numerically. The sidewalls of the cavity, which move upwards, are kept at low-temperature Tc while only a part in the center of the bottom wall is kept at high-temperature Th and the remaining parts are kept adiabatic. The governing equations, in stream function–vorticity form, are discretized and solved using the finite difference method. Particular attention was paid to the influence of the Prandtl numbers of 5.534, 3.045 and 2, corresponding respectively to the water temperatures of 303.15 K, 333.15 K and 363.15 K. The numerical results are presented in the form of streamlines, isotherms, and entropy generation contours for different values of the Richardson numbers at an arbitrary Reynolds number Re=102. Besides this, the evolution of the average Nusselt number and the average entropy generation is also reported. The obtained results show interesting behaviors of the flow and thermal fields, which mainly involve stable symmetric and non-symmetric steady-state solutions, as well as unsteady regimes, depending on specific values of the Richardson and Prandtl numbers. It is additionally observed that the average Nusselt number increases and the average entropy generation decreases when both the Richardson and Prandtl numbers increase.

The results of dynamic compression tests of aspen under elevated temperature up to +60°C are presented. The tests were carried out based on the Kolsky method using the split Hopkinson pressure bar. To study the anisotropy of properties, aspen samples were fabricated and tested by cutting along and across the fibers direction. Dynamic stress-strain curves were obtained as well as the average values of modulus of active loading sites. The greatest steepness of the loading branches and the highest breaking stresses are observed for the samples loaded along the fiber direction, while the smallest values are noted under loading across the fiber direction. Also the effect of elevated temperature on strength and deformation properties of aspen is estimated.

This work is devoted to the systematic numerical simulation of oil displacement using nanosuspension with silicon oxide particles with concentration of up to 1 wt% and particle sizes of 5 nm. The influence of such factors as core wettability, concentration of nanoparticles, capillary number, and oil viscosity on the enhanced oil recovery by nanosuspension has been systematically investigated using the VOF method for 2D-dimensional micromodels. Various rocks were considered: dolomite, metabasalt and sandstone. It is shown that the oil recovery coefficient improves for all considered types of rock with increasing nanoparticle concentration. The most effective application of nanosuspension for enhanced oil recovery is observed at a low capillary number, corresponding to the capillary displacement mode. The addition of nanoparticles facilitates increasing oil recovery factor in a wide range of viscosity ratios between oil and displacement fluid.

Topology optimization is a methodology widely used in the design phase that has gained space in engineering. On the other hand, uncertainty is present in material properties, loads, and boundary conditions in practically any design. The main goal for this paper lies in the coupling of the two subjects to account for uncertainties in the topology optimization. The Proportional Topology Optimization method renders the possibility of treating the stress constraints in a unified way. This allows topologies that at the same time preserve structural reliability and optimize costs. The Proportional Topology Optimization method under the reliability constraint is presented for isostatic and hyperstatic beam examples with stress and displacement LSF.

The boundary element method is used to analyze the problem of dynamic loading acting inside a cubic cavity located in a partially saturated poroelastic halfspace. Defining relations of a Biot’s porous medium are used, which are written in Laplace representations for unknown functions of displacements of the skeleton and pore pressures of the fillers. Solutions in time are obtained using the stepped method of numerical inversion of Laplace transforms. Dynamic responses of displacements and pore pressures at points on the surface of the halfspace and the cavity have been constructed. The effect of the values of the saturation coefficient and of the depth of the location of the cavity on dynamic responses has been studied.

Genetic-algorithm methods are used here for single-objective (SO) and multi-objective (MO) geometrical optimizations of jet pumps used in vacuum distillation of ethanol, an application not deeply studied in scientific literature. These devices are particularly suitable to allow the azeotrope-breaking below the atmospheric pressure at ambient temperature. Based on this, different working pressures (Pp), five non-dimensional geometrical parameters that can influence the jet pump operation, and three performance parameters (drag coefficient, pressure recovery ratio and energy efficiency) are considered in this work. Furthermore, using a central composite, face-centered, enhanced experimental design, 89 simulation experiments are run to obtain Response Surfaces (RS) by genetic aggregation, applying afterwards the SOGA and MOGA optimization methods. Also, Spearman Rank-order correlation matrix is employed as initial screening, finding strongly negative correlation of drag coefficient and efficiency with the working pressure, Pp. Computational Fluid Dynamic (CFD) model is validated with other numerical and experimental works, obtaining satisfactory results. Additionally, the change of the optimized input and output parameters with Pp is studied, along with the behavior of Mach number. It can be concluded that the optimal nozzle parameters evidently influenced by Pp for the SO optimization are: outlet diameter and length of divergent part, conicity of convergent part, and ratio of inlet to throat area. For the MO optimization, changes of optimized geometrical parameters with Pp are negligible. In contrast, performance parameters are importantly influenced by Pp for all optimizations.

This work focuses on the mechanical characterisation of adhesives with hyperelastic behaviour, and on the determination of the behavioural laws that best represent them, in order to be able to introduce them into simulation models. There are virtually no references to the characterisation of these materials in the literature, so it has been decided to use the methodologies commonly employed with other hyperelastic materials, such as rubber, whose behaviour is similar to that of highly flexible adhesives. Firstly, a test plan is carried out on simple specimens, uniaxial and planar configurations, designed to measure the non-linear behaviour of the adhesives in both tension and shear. Subsequently, using finite element models of the tested specimens, different behavioural laws from those usually used for the representation of hyperelastic materials are tested. Based on the experimental results, the parameters of the different laws proposed are adjusted, and the results are compared. In conclusion, it has been determined that the Mooney-Rivlin model is the one that allows the best fit, and therefore may be the most suitable to represent the behaviour of hyperelastic adhesives. For the adhesive used in this work, the obtained law has been validated by comparing the results of tests on single lap adhesive join (SLJ) specimens with the results predicted by the simulation.

This paper analyzes the effects of periodic external loading on the longitudinal fracture of a beam structure made of linear viscoelastic material. A longitudinal crack splits the cracked part of the beam into left-hand and right-hand crack arms. The beam is under a bending moment applied at the free end of the right-hand crack arm. The bending moment varies periodically with time. The material of the beam is continuously inhomogeneous (functionally graded) along the thickness. Thus, the modulus of elasticity and the coefficient of viscosity of the material vary continuously in transversal direction of the beam. The balance of the energy in the beam under periodic bending moment is analyzed in order to derive the strain energy release rate for the longitudinal crack. The solution is verified by deriving the strain energy release rate by analyzing of the compliance of the beam subjected to periodic bending moment. An investigation is carried-out by applying the solutions obtained in order to evaluate the effects of the parameters of the periodic loading on the strain energy release rate.

There is a class of tasks that requires considering the dynamics not only for rolling stock but also for the response of the railway track. One of the directions of railway transport development, which encourages the transition to fundamentally new dynamic models of the railway track, is undoubtedly an increase in traffic speed. To solve such problems, the authors applied a model of the stressed-strained state of a railway track based on the dynamic problem of elasticity theory. The feature of this model is the calculation of dynamic stresses and deformations induced by the spread of elastic waves through the objects of the railway track. Based on the mathematical modeling of stress propagation in the under-rail basis, authors have shown the influence of various objects of a railway track on the formation of the outline of the front of the elastic wave and determined the main time intervals. Furthermore, the authors propose the following analytical method, which, in addition to the soil's physical and mechanical properties, considers the properties of the ballast as a layer that transmits pressure to the roadbed and takes an active part in the formation of the interaction space.

This study aims to mitigate the gap of knowledge on the cyclic bond behaviour of Carbon Fiber Reinforced Polymer (CFRP) bonded onto a steel substrate. The Distinct Element Method was used to model different bonding techniques such as Externally Bonded Reinforcement (for reference purposes); the linear increase of the width of the CFRP composite; the assumption of a mixed adhesive; and using an additional steel plate bonded on the top of the CFRP. Compared with the monotonic loading simulations, the load capacity and ductility of the joints with the lowest overlapped bonded lengths decreased with the number of cycles. However, the strength of the CFRP-to-steel joints was not affected if the overlapping bonded joint had a long length.