Journal of Applied and Computational Mechanics
https://jacm.scu.ac.ir/
Journal of Applied and Computational Mechanicsendaily1Mon, 01 Jan 2024 00:00:00 +0330Mon, 01 Jan 2024 00:00:00 +0330Inhomogeneous Gradient Poiseuille Flows of a Vertically Swirled Fluid
https://jacm.scu.ac.ir/article_18356.html
An exact solution is proposed for describing the steady-state and unsteady gradient Poiseuille shear flow of a viscous incompressible fluid in a horizontal infinite layer. This exact solution is described by a polynomial of degree N with respect to the variable y where the coefficients of the polynomial depend on the coordinate z and time t, a boundary value problem for a steady flow has been considered and the velocity field with a quadratic dependence on the horizontal longitudinal (horizontal) coordinate y is considered. The coefficients of the quadratic form depend on the transverse (vertical) coordinate z. Pressure is a linear form of the horizontal coordinates x and y. The exact solution of the constitutive system of equations for the boundary value problem is considered here to be polynomial. The boundary value problem is solved for a non-uniform distribution of velocities on the upper non-deformable boundary of an infinite horizontal liquid layer. The no-slip condition is set on the lower non-deformable boundary. The exact solution obtained is a polynomial of the tenth degree in the coordinates x, y and z. Stratification conditions are obtained for the velocity field, for the stress tensor components, and for the vorticity vector. The constructed exact solution describes the counterflows of a vertically swirling fluid outside the field of the Coriolis force. Shear stresses are tensile and compressive relative to the vertical (transverse) coordinates and relative to the horizontal (longitudinal) coordinates. The article presents formulas illustrating the existence of zones of differently directed vortices.Oil Immersed Distribution Transformer HST Reduction using Vegetable Oils and ONAN Cooling
https://jacm.scu.ac.ir/article_18414.html
Today, the use of electricity sources is increasing as cities are growing. With the increasing use of mineral oils for transformers cooling in the distribution network, due to the problems encountered using these oils, an alternative fluid should be used inside the transformers instead of mineral oils. Therefore, mineral oils should be replaced with fluids that are more compatible with nature due to the environmental hazards and high costs. Hence, vegetable oils can be used as suitable alternatives for the mineral oils in transformers due to their low risk and the renewability. On the other hand, compared to the mineral oils that have a fire point of about 151 Celsius degrees, vegetable oils have fire points higher than 311 Celsius degrees. As a result, from this viewpoint, they are considered as harmless fluids. Vegetable oils are simply degraded in the nature, and due to their different chemical structures compared to the mineral oils, they can increase the life of the equipment. Besides, the most important point is that they improve the transformer cooling performance, in terms of thermal analysis. Thus, in this paper, the distribution transformer electromagnetic-thermal analysis and conjugate heat transfer, in presence of different types of vegetable oils, and different types of cores such as grain-oriented silicon steel, amorphous and vitroperm alloy are investigated. Afterwards, the obtained results, especially hot spot temperature, are compared with distribution transformer containing mineral oil. ANSYS software has also been used for simulations.Investigation of the Static Bending Response of FGM Sandwich Plates
https://jacm.scu.ac.ir/article_18421.html
In the present work, a displacement-based high-order shear deformation theory is introduced for the static response of functionally graded plates. The present theory is variationally consistent and strongly similar to the classical plate theory in many aspects. It does not require the shear correction factor, and gives rise to the transverse shear stress variation so that the transverse shear stresses vary parabolically across the thickness to satisfy free surface conditions for the shear stress. By dividing the transverse displacement into the bending and shear parts and making further assumptions, the number of unknowns and equations of motion of the present theory is reduced a and hence makes them simple to use. The material properties of the plate are assumed to be graded in the thickness direction according to a simple power-law distribution in terms of volume fractions of material constituents. The equilibrium equations of a functionally graded plate are given based on the higher order shear deformation theory. The numerical results presented in the paper are demonstrated by comparing the results with solutions derived from other higher-order models found in the literature and the present numerical results of Finite Element Analysis (FEA). In the numerical results, the effects of the grading materials, lay-up scheme and aspect ratio on the normal stress, shear stress and static deflections of the functionally graded sandwich plates are presented and discussed. It can be concluded that the proposed theory is accurate, elegant and simple in solving the problem of the bending behavior of functionally graded plates.&nbsp;Assessment of the Turbine Location for Optimum Performance of the Solar Vortex Engine as a Replacement to the Tall Chimney Solar Updraft Power Plant Design
https://jacm.scu.ac.ir/article_18441.html
The solar vortex engine (SVE) aims to replace the tall and expensive chimney structure in solar updraft power plants by a shorter less expensive structure named the vortex generator. In this study, the entire SVE system is simulated by CFD to determine the appropriate location for the turbine unit as well as prove the capability of the vortex generator in replacing the chimney. Three different cases for the SVE are considered and compared to corresponding cases of the solar chimney power plant (SCPP). Results revealed that the optimum turbine location is at the outlet hole of the vortex generator. An updraft air velocity of 1.82 m/s was achieved at the outlet hole, compared to 1.56 m/s at the base of a solar chimney with the same diameter as the upper hole. The consideration of the turbine pressure drop did not affect the formation and preservation of the air vortex. So, the 1 m high vortex generator successfully replaced the 8.6 m chimney component in solar updraft power plants, greatly reducing the cost and construction complexity of the plant. The vortex generator accelerated the air delivered from the solar collector, increasing its velocity by 14 times. The SVE&rsquo;s power output is directly proportional to the static pressure drop across the turbine. The mean difference values along the air vortex field between the cases with and without a turbine are 0.67 Pa and 0.026 m/s for the static pressure drop and velocity magnitude, respectively.Influence of Discretely Introduced Cutouts on the Buckling of Shallow Shells with Double Curvature
https://jacm.scu.ac.ir/article_18444.html
The paper analyzes the influence of cutouts on the buckling of shallow shells with double curvature. Based on the Timoshenko-Reissner hypothesis, a mathematical model is presented that considers transverse shifts, material orthotropy, geometric nonlinearity and structural weakening by cutouts. Cutouts are specified discretely by single columnar functions. The computational algorithm is based on the Ritz method and the Newton method. The implementation of the algorithm is carried out in the Maple 2022 software package. To study the buckling, the Lyapunov criterion is adopted. Calculations of the buckling of flat shells of double curvature with square cuts, graphs of the dependence of deflections on loads and deflection fields are given. Accounting for the structural cutouts leads to a decrease in the critical load. At the same time, for the considered problems, it is found that the decrease in the critical load does not exceed 25&nbsp;% for the cutout volume not exceeding 10&nbsp;% of the shell volume.A New Class of Linear Canonical Wavelet Transform
https://jacm.scu.ac.ir/article_18462.html
We define a new class of linear canonical wavelet transform (LCWT) and study its properties like inner product relation, reconstruction formula and also characterize its range. We obtain Donoho-Stark&rsquo;s uncertainty principle for the LCWT and give a lower bound for the measure of its essential support. We also give the Shapiro&rsquo;s mean dispersion theorem for the proposed LCWT.Optimizing Multidirectional Torsional Hysteretic Damper Specifications using Harmony Search
https://jacm.scu.ac.ir/article_18465.html
Multidirectional torsional hysteretic damper is a new type of damper that can be used to isolate and dissipate seismic effects on a structure. It can be designed to have a controllable post-elastic stiffness and exhibit high levels of damping as well as stable cyclic response. In this article, while offering a simplified numerical relationship for force-displacement response of the damper, the structure that is fitted with this innovative type of damper is optimized using the harmony search optimization procedure with discrete design variables. Numerical experiments show that the harmony search methodology can determine the damper parameters with high computational efficiency and outperform genetic algorithm and simulated annealing procedure in this regard.Musculoskeletal Modeling and Control of the Human Upper Limb during Manual Wheelchair Propulsion: Application in Functional Electrical Stimulation Rehabilitation Therapy
https://jacm.scu.ac.ir/article_18474.html
Manual wheelchair users rely on their upper limbs for independence and daily activities. The high incidence of upper limb injuries can be attributed to the significant muscular demands imposed by propulsion as a repetitive movement. People with spinal cord injury are at high risk for upper limb injuries, including neuromusculoskeletal pathologies and nociceptive pain, as human upper limbs are poorly designed to facilitate chronic weight-bearing activities, such as manual wheelchair propulsion. Comprehending the underlying biomechanical mechanisms of motor control and developing appropriate rehabilitation tasks are essential to deal with the effects of poor motor control on the performance of manual wheelchair users and prevent long-term upper limb disability, which can interrupt electrical signals between the brain and muscles. Functional electrical stimulation utilizes low-intensity electrical signals to artificially generate body movements by stimulating the damaged peripheral nerves of patients with impaired motor control. Therefore, this study investigates the central nervous system strategy to control human movements, which can be used for task-specific functional electrical stimulation rehabilitation therapy. To this aim, two degrees of freedom musculoskeletal model of the upper limb, including six muscles, is developed, and an optimal controller consisting of two separate optimal parts is proposed to track the desired trajectories in the joint space and estimate the optimal muscle activations regarding physiological constraints. The simulation results are validated with electromyography datasets collected from twelve participants. This study's primary advantages are generating optimal joint torques, accurate trajectory tracking, and good similarities between estimated and measured muscle activations.Thermoelastic Modeling with Dual Porosity Interacting with an Inviscid Liquid
https://jacm.scu.ac.ir/article_18477.html
This study introduces a two-dimensional thermoelastic model for a homogeneous isotropic half-space with double porosity underlying an inviscid liquid half-space featuring temperature variations. The model incorporates the three-phase lag (TPL) heat equation and reveals that in the solid half-space, four coupled longitudinal waves intertwine with one uncoupled transverse wave, while one mechanical wave ripples through the liquid half-space. The investigation highlights dispersion, attenuation, and other effects affected by the thermal properties and the presence of voids. Using plane wave solutions and boundary conditions at the interface, a concise expression for the frequency equation of the model has been derived. Furthermore, the magnitudes of the displacements in the solid half-space and liquid half-spaces, the temperature change, and the volume fractional fields at the interface have been precisely determined. In the graphical section, computer-simulated results of various wave profiles for magnesium crystal material have been generated for different heat conduction thermoelastic models. The study's implications span various fields, such as hydrology, engineering, ultrasonics, navigation, and electronics.Mathematical Modelling of MHD Blood Flow with Gold Nanoparticles in Slip Small Arteries
https://jacm.scu.ac.ir/article_18495.html
Nanofluid is an innovative technology that is essential in biomedical applications. A nanofluid study of human blood flow mathematically is more favorable since it provides a hypothesis for complex systems faster and is cost-saving. Academic researchers have expressed interest in investigating the characteristics of Casson nanofluid flow within a cylindrical structure, which serves as a representative model for the flow of blood in constricted human arteries. However, slip velocity boundary conditions were considered by only a certain number of researchers. The goal of this study is to develop mathematical modelling of Casson fluid flow with gold nanoparticles in the slip cylinder. The impacts of convective heat transfer, magnetohydrodynamics (MHD), and porous medium are also investigated. The Tiwari-Das nanofluid model is utilized in the governing equations. Then, the governing equations with the related boundary conditions are transformed into dimensionless form. The analytical solutions were obtained through the use of the Laplace transform and the finite Hankel transform in combination. The results of nanofluid velocity, temperature, skin friction, and Nusselt number are analyzed through the use of graphs and tables containing relevant parameters. Slip velocity causes an increment in blood velocity and a decrement in skin friction. Blood velocity and temperature are enhanced as the nanoparticles' volume fraction is increased. It is significant in cancer treatment to increase the heat transfer rate at targeted cancerous cells.Thermal Behavior of Mesoporous Aramid Fiber Reinforced Silica Aerogel Composite for Thermal Insulation Applications: Microscale Modeling
https://jacm.scu.ac.ir/article_18499.html
This paper explores the incorporation of aramid fibers, recognized for their high mechanical flexibility and low thermal conductivity (TC), to serve as reinforcing agents within the highly porous aerogel matrix in order to overcome their fragility and weak mechanical structure that impose limitations on their practical utility especially in piping insulation. The thermal properties are determined using a micromechanical modeling approach that considers parameters such as temperature, fiber volume fraction, thermal conductivity, and porosity of the silica aerogel. For specific conditions, including an Aramid fiber radius of 6 microns, a silica aerogel thermal conductivity of 0.017 W.m-1.K-1, and a porosity of 95%, the resulting AFRA composite exhibits an Effective Thermal Conductivity (ETC) of 0.0234 W.m-1.K-1. Notably, this value is lower than the thermal conductivity of air at ambient temperature. The findings are further validated through experimental and analytical techniques. A response surface methodology (RSM) based on Box-Behnken design (BBD) is employed. This approach leads to the development of a quadratic equation intricately relating the key parameters to the ETC of the AFRA. The aim is optimization, identifying target optimal values for these parameters to further enhance the performance of AFRA composites.Sizing the Actuators for a Dragon Fly Prototype
https://jacm.scu.ac.ir/article_18509.html
In order to improve the design of the actuators of a Dragon Fly prototype, we study the loads applied to the actuators in operation. Both external and inertial forces are taken into account, as well as internal loads, for the purposes of evaluating the influence of the compliance of the arms on that of the "end-effector". We have shown many inadequacies of the arms regarding the stiffness needed to meet the initial design requirements. In order to reduce these inadequacies, a careful structural analysis of the stiffness of the actuators is carried out with a FEM technique, aimed at identifying the design methodology necessary to identify the mechanical elements of the arms to be stiffened. As an example, the design of the actuators is presented, with the aim of proposing an indirect calibration strategy. We have shown that the performances of the Dragon Fly prototype can be improved by developing and including in the control system a suitable module to compensate the incoming errors. By implementing our model in some practical simulations, with a maximum load on the actuators, and internal stresses, we have shown the efficiency of our model by collected experimental data. A FEM analysis is carried out on each actuator to identify the critical elements to be stiffened, and a calibration strategy is used to evaluate and compensate the expected kinematic errors due to gravity and external loads. The obtained results are used to assess the size of the actuators. The sensitivity analysis on the effects of global compliance within the structure enables us to identify and stiffen the critical elements (typically the extremities of the actuators). The worst loading conditions have been evaluated, by considering the internal loads in the critical points of the machine structure results in enabling us the sizing of the actuators. So that the Dragon fly prototype project has been set up, and the first optimal design of the arms has been performed by means of FEM analysis.Investigation of Visco-rheological Properties of Polymeric Fluid on Electrothermal Pumping
https://jacm.scu.ac.ir/article_18521.html
Electrothermal pumping is a recently trending method to force highly conductive fluids in a wide range of microfluidics applications with biological processes. Although most polymer fluids (biological and synthetic) are highly conductive exhibiting viscoelastic rheological properties that are relevant to biomedical applications, their behavior under the effect of electrothermal force has not yet been studied. To this aim, the PTT model (non-linear rheological constitutive equation) and electrothermal equations are implemented in the developed OpenFOAM solver. The effect of rheological characteristics of the fluids on the physical parameters such as velocity, elastic behavior, and vortices strength of electrothermal flow are investigated through the viscoelastic non-dimensional numbers. According to the results, electrothermal outlet velocity decreases by 726% as the retardation ratio (&beta; number) increases from 0.2 to 0.9 and increases by 107% as the Weissenberg number raises from 0.001 to 10. Investigating all non-dimensional numbers simultaneously leads to the conclusion that higher electrothermal velocity is achieved by viscoelastic fluids with lower viscosity and higher relaxation time. This fact is useful for choosing the proper fluid for a particular application. As a practical example, 3000 ppm polyethylene oxide solution results in higher velocity in electrothermal flow compared to the 5% polyvinylpyrrolidone and 2000 ppm xanthan gum solution.3D Numerical Investigation of Heat Transfer Performance in Liquid-liquid Taylor Flow
https://jacm.scu.ac.ir/article_18524.html
With recent advances in semiconductor technology, conventional cooling methods and standard coolants are no longer adequate to manage electronic chips&rsquo; enormous heat generation. Therefore, innovative cooling solutions are required to maintain these devices at optimum operating temperatures. Taylor flow in microchannels is an effective technique that allows excellent mixing of two fluids, which is crucial for heat transfer. A 3D numerical analysis of the heat transfer performance of liquid-liquid Taylor flow in a rectangular microchannel was carried out by ANYSY Fluent. Water droplets were dispersed in either ethylene or propylene glycol, with the interface between the two fluids captured using the Volume of Fluid method. For optimal computational time, two symmetries in the XY and XZ planes are considered. Furthermore, mesh size refinement was performed in the near-wall region to capture the liquid film. An analysis of the effect of plug/slug length and liquid film thickness is conducted with initially constant thermo-physical properties. This assumption was considered to analyse the heat transfer process and determine the most critical parameter affecting heat transfer performance. A user-defined function is then implemented in ANSYS Fluent to examine the effect of working fluids temperature-dependent viscosity change on the heat transfer rate. Conjugate heat transfer and axial conduction are also examined, as these two factors can significantly affect the thermal behaviour inside the microchannel and enable the achievement of realistic and accurate results. The results reveal that Taylor liquid-liquid flow can increase the heat transfer rate by up to 440% over single-phase flow. It was also found that the temperature-dependent viscosity of the working fluids significantly affects the plug/slug length and liquid film thickness, resulting in a 20.8% improvement in heat transfer rate compared with constant thermo-physical properties. This study will improve the state of knowledge on heat transfer by Taylor flow in microchannels and factors that can influence it, and highlight the significance of this flow pattern in enhancing heat transfer performance over single-phase flow.The Structural Synthesis of Non-fractionated, Three-degree-of-freedom Planetary Gear Mechanisms
https://jacm.scu.ac.ir/article_18567.html
Planetary gear trains (PGTs) with one or more degrees of freedom (DOFs) have numerous uses in PGT-based mechanisms. The majority of the currently available synthesis methods have focused on 1-DOF PGTs, with only a few investigations on multi-DOF PGT synthesis. The method for synthesizing 7-link 3-DOF PGMs is outlined. All possible link assortments are produced, labeled spanning trees are generated, and potential geared graphs are constructed. The guidelines for including geared edges and how to synthesize geared graphs are outlined. Vertex-degree arrays are generated to validate the geared graphs. Isomorphic geared graphs are identified by comparing the isomorphic identification numbers of geared graphs with the same spanning tree. Fractionated geared graphs are identified using the reachability matrix method. The new method has a straightforward algorithm. In contrast to what is reported in the literature, the results of the synthesis of 7-link 3-DOF PGMs show that there are seven non-fractionated mechanisms. MATLAB programs are used to acquire the vertex-degree arrays.On the Thermomechanical Behavior of Laminated Composite Plates using different Micromechanical-based Models for Coefficients of Thermal Expansion (CTE)
https://jacm.scu.ac.ir/article_18568.html
In this paper, the influence of the Coefficient of Thermal Expansion (CTE) on the thermal stress analysis of laminated composite plates is explored. By introducing the undetermined integral terms in the displacement field, a new simple and efficient higher-order shear deformation theory is formulated for the thermo-mechanical behavior of thick laminated composite plates. This formulation aims to reduce the number of generated unknowns. Typically, a reduced order of the governing partial differential equations is expressed using the principle of virtual displacements. By using Navier&rsquo;s technique, closed-form solutions are derived for laminated composite plates under thermal and/or mechanical loading. Unfortunately, several traditional research investigations significantly depend on the rule of the mixture to determine reliable CTE for composites. This paper offers and examines a variety of analytical micromechanics-based models for estimating CTE&nbsp;in laminated composite materials, incorporating into consideration different considerations. The obtained results are compared to those given by other alternative plate theories, and the efficiency and accuracy of the present theory are demonstrated for the thermomechanical behavior of laminated composite plates. This study reviews and applies several micromechanics-based models, contrary to previous investigations. Laminated composite plates could delaminate or crack due to the matrix material's longitudinal CTE, affecting fiber volume fraction and stacking sequence. Micromechanics-based approaches are important when arbitrary thermo-mechanical characteristics can generate inaccuracies. Interestingly, micromechanics-based models can estimate effective CTE. Schapery, Chamberlain, and Chamis provide models with identical longitudinal CTE. For increasing fiber volume fractions, Chamberlain's model is more sensitive to increasing fiber volume fractions. Mechanical stress changes laminated plate behavior more than thermal loading. Although all presented micromechanical-based models have simplified representations, this research attempts to provide a standard for future investigations. The use of detailed micromechanical-based models stimulates further progress in understanding and utilizing complex composite plates.Application of Breakage Models to Particle Speeds Simulated by Discrete Element Methods
https://jacm.scu.ac.ir/article_18576.html
Simulations that calculate the breakage of a given material allow for estimating the particle size produced by comminution equipment. However, conducting these simulations requires a significant amount of time and incurs high computational costs due to the progressive increase in the number of particles during the breakage events. This challenge has prompted the exploration of alternatives, such as employing impact energies present in simulations with solid particles. This study examines the application of two breakage models to particle speeds, analyzing the correlation between the t10 value obtained from simulations using solid particles and the value obtained when simulations include breakage. The findings reveal a linear relationship between the results obtained from simulations with breakage and those with solid particles for a rotor that primarily impacts particles during their initial collisions. This relationship holds true for variations in rotor RPM as well as fluctuations in feed flow.Study of Hybrid Composite Joints with Thin-ply-reinforced Adherends under High-rate and Impact Loadings
https://jacm.scu.ac.ir/article_18579.html
This research aims to examine the tensile strength of a hybrid composite laminate reinforced by thin-plies when used as an adherend in bonded single lap joints subjected to high-rate and impact loading. Two different composites, namely Texipreg HS 160 T700 and NTPT-TP415, are employed as the conventional and thin-ply composites, respectively. The study considers three configurations: a conventional composite, a thin-ply, and a hybrid single lap joint. Numerical models of the configurations are developed to provide insight into failure mechanisms and the initiation of damage. The results indicate a significant increase in tensile strength for the hybrid joints over the conventional and thin-ply joints, due to the mitigation of stress concentrations. Overall, this study demonstrates the potential of hybrid laminates for improving the performance of composite joints under high-rate loading and impact conditions.Unsteady Meshfree Framework for Double-diffusive Natural Convection with Boundary and Geometry Effects
https://jacm.scu.ac.ir/article_18580.html
In this study, a meshfree framework based on the reproducing kernel collocation method is proposed for incremental-iterative analysis of double-diffusive natural convection in a porous enclosure, in which the forward difference method is adopted for temporal discretization, and the two-step version of Newton-Raphson method is used for iteration. As the double-diffusive convection problem is composed of multi phases and is influenced by both material and geometric parameters, the resulting system is highly nonlinear and complicated. From the numerical investigation, the partially heated boundary with different buoyancy ratios can yield monocellular flow problems with opposite phenomena depending on the contribution of thermal/solute buoyancy force. For the domains with burrowing inside, the key feature is the contour of stream function, which is separated into two vortexes by the hole in the simply connected domain while the two vortexes are not separated completely in the multiply connected domain due to the geometric compression of two holes. It is further shown that the framework is capable of solving various double-diffusive convection problems with satisfactory accuracy and efficiency by uniform discretization as well as few source points in the approximation.Entropy Analysis of Darcy-Forchheimer Model of Prandtl Nanofluid over a Curved Stretching Sheet and Heat Transfer Optimization by ANOVA-Taguchi Technique
https://jacm.scu.ac.ir/article_18604.html
Darcy-Forchheimer model has been used to consider the mathematical and statistical aspects of Prandtl nanofluid flow on a stretched curvy geometry, with homogenic-heterogenic reactions, nonlinear radiation, exponential heat, Joule heating, velocity slip, and convective heat conditions. An account of entropy significance has been given to boost the applicability of the study. The 4-5th ordered numerical tool, Runge-Kutta-Fehlberg, has been employed to establish the plots for the considered flow. ANOVA and Taguchi optimisation technique is used to obtain the optimal condition in enhancing the heat transfer rate for modelled mathematical problem. Here, the study reveals that the increasing homo-heterogenic strength parameters foster the concentration profile. The study also found that the thermal curves are positively affected by the radiation parameter and the temperature differential parameter. In addition to this, graphical portraits of isotherms and streamlines have been given to characterise the flow and heat pattern. Taguchi method reveal that first level of Prandtl number, magnetic parameter, Weissenberg number, heat source parameter and third level of curvature parameter, produce maximum Nusselt number. Heat source parameter has large contribution of about 49.45% among the other parameters and Prandtl number has the least contribution of about 1.4% for optimisation.Thermal Performance Study of Plate-finned Vapor Chamber Heat Sink
https://jacm.scu.ac.ir/article_18606.html
This study focuses on improving the thermal characteristics of a plate-finned heat sink (PFHS) by incorporating a vapor chamber (VC) through experimental investigation. The research examines the influence of various parameters, including Reynolds number (Re), heat input, filling ratio (FR), and operating vacuum pressure, on the thermal performance of the VC. The results demonstrate that the utilization of a VC leads to a significantly more uniform temperature distribution along the base of the PFHS and low overall temperatures. Conversely, in the absence of a VC, the PFHS exhibits a non-uniform temperature distribution, with a bell-shaped profile and concentrated high temperatures at the center at the same operating conditions. The results indicate that an operating vacuum pressure of 1kPa produces the most favorable performance. Additionally, a filling ratio of 50% proves to be optimal across the range of heat inputs from 10 to 90 W.Dynamics of damped and undamped wave natures of the fractional Kraenkel-Manna-Merle system in in ferromagnetic materials
https://jacm.scu.ac.ir/article_18685.html
This research considered the Kraenkel-Manna-Merle system with an M-truncated derivative (K-M-M-S-M-T-D) that defines the magnetic field propagation (M-F-P) in ferromagnetic materials with zero conductivity (F-M-Z-C) and used the Sardar sub-equation method (S-S-E-M). Our goal is to acquire soliton solutions (SSs) of K-M-M-S-M-T-D via the S-S-E-M. To our knowledge, no one has considered the SSs to the K-M-M-S-MTD with or without a damping effect (DE) via the S-S-E-M. The SSs are achieved as the M-shape, periodic wave shape, W-shape, kink, anti-parabolic, and singular kink solitons in terms of free parameters. We utilize Maple to expose pictures in three-dimensional (3-D), contour and two-dimensional (2-D) for different values of fractional order (FO) of the got SSs, and we discuss the effect of the FO of the K-M-M-S-MTD via the S-S-E-M, which has not been discussed in the previous literature. All wave phenomena are applied to optical fiber communication, signal transmission, porous mediums, magneto-acoustic waves in plasma, electromagnetism, fluid dynamics, chaotic systems, coastal engineering, and so on. The achieved SSs prove that the S-S-E-M is very simple and effective for nonlinear science and engineering for examining nonlinear fractional differential equations (N-L-F-D-Es).A novel exponential zigzag function coupled high-order beam theory for advanced laminated composite analysis.
https://jacm.scu.ac.ir/article_18698.html
Various industrial sectors require highly specialized and efficient materials for applications in fields such as the military, aeronautics, aerospace, and mechanical and civil engineering. Composite materials that meet the stringent requirements across these domains have become prominent, often serving as structural components and requiring precise mathematical modeling. Zigzag (ZZ) and Layerwise (LW) theories are commonly used for laminated-beam structural analysis. Although the LW theory provides superior accuracy, it suffers from an increase in unknowns as the number of layers grows. Conversely, the ZZ theory is less computationally intensive and less accurate. This study proposes an exponential high-order zigzag function with a unified kinematic formulation to enhance the accuracy of the ZZ theory. The results were compared with those of existing models and demonstrated excellent agreement with the reference solutions, irrespective of the layer count or slenderness index, making it a more efficient choice for laminated-beam analysis.