جستجوی مقالات مرتبط با کلیدواژه "fem" در نشریات گروه "مکانیک"

This paper outlines the conceptual and numerical design process of a comminution equipment centered on particle breakdown through impact. The process is divided into four stages, starting with the generation of device concepts achieved by developing a needs matrix for an optimal machine. Subsequently, in the second stage, various equipment shape proposals were introduced and tested, with the selection of an optimal proposal determined through performance comparisons. For comparison purposes, simulations utilizing the discrete element method (DEM) were conducted, considering analyses of accumulated power from collisions and particle breakage. Once the optimized prototype was identified, a breakage simulation was conducted to measure the device's reduction ratio. In the third stage, the machine elements of the device were calculated. Finally, in the fourth stage, a series of simulations utilizing the finite element method (FEM) were carried out to perform structural and modal analyses of the final design. The evaluated variables identified in the simulations played a crucial role in optimizing the design, ultimately resulting in a device with a reduction ratio of 1:19.8 for limestone.

Temperature prediction is essential for assessing the state of stresses, strains, and material flow during friction stir welding (FSW). In this context, the thermal and mechanical behavior of the AA6063-T5 aluminum alloy was simulated in FSW. This research utilized the Finite Element Method (FEM) for thermal and mechanical simulations, employing Abaqus/Explicit software. The first simulation focused on the thermal model, implemented through coding in FORTRAN using the Schmidt-Hotel reference model, which investigates the temperature distribution of the alloy. The second simulation was mechanical in nature; it utilized the output results from the thermal simulation to examine the stresses resulting from the FSW process. The samples were made of the same material and were butt-jointed for the operation. A tool speed of 60 mm/min, a force of 4000 newtons, and a coefficient of friction of 0.4 were applied during this process. The parameters for thermal conductivity, specific heat, coefficient of expansion, and Young's modulus were defined as temperature-dependent. The results indicated that the temperature distribution diagram at a specific point along the welding path closely matched practical examples of the FSW process. The temperature distribution contours at the beginning, middle, and end of the welding path, as well as the temperature distribution across the cross-sectional surface of the weld in the middle of the piece, were consistent with the samples. Additionally, the diagram and contour of the longitudinal residual stress in the workpiece aligned well with the completed samples.

Pipeline systems under thermal loads are frequently used in different industries, such as the power plants and petrochemicals. Unlike the analytical method of elastic center, which is capable to analyze only one branch of pipeline with pipe members parallel to the coordinate system, the method of stiffness removes these limitations. In this article the stiffness method is introduced for the analysis of pipeline systems. Based on this method, the piping system may include any number of piping braches. The straight pipe elements in the branch may have any general orientation and the bend elements may have any arbitrary angle. The computer program designed based on this method may compute the nodal displacements at the ends of the straight or bend elements and present three components for loads and three components for moments. Once the free-body diagram of each piping elements with nodal forces and moments are drawn, then the engineering codes are employed to design the piping system for safe operation.

In this paper, we employ the finite element method based on non-uniform rational B-splines function approximation to solve the nonlinear Brinkman-Forcheimer-Darcy equation in a simply connected and bounded Lipschitz domain Ω. We provide both theoretical and numerical studies of the Dirichlet boundary problem. Utilizing a stream function formulation, we demonstrate the well-posedness of the weak form. Furthermore, we approximate the velocity and pressure fields by linearizing the nonlinear terms, resulting in an algebraic system. This Non-uniform rational B-splines method is more effective in terms of the exact representation of the geometry and the good approximation of the solution compared to the virtual element method. To validate the effectiveness of the non-uniform rational B-splines Finite Element Method, we conduct numerical simulations of fluid flow in porous media.

This study aimed to investigate the influence of rotational and traverse speeds on the friction stir welding (FSW) of aerospace-grade aluminum alloys. To achieve this, a thermo-mechanically coupled 3D finite element analysis (FEM) was employed to analyze the impact of these speeds on temperature and strain. Additionally, tensile tests were conducted on welded joints fabricated using varying tool rotational and traverse speeds to examine the effects of welding speed on the tensile properties of the specimens. The results revealed that high welding speeds had a detrimental effect on the mechanical properties of the weld samples. Samples produced using an optimal rotational speed of 1200 rpm and a traverse speed of 40 mm exhibited a tensile strength of 346 MPa, which accounts for approximately 64% of the strength seen in the base material.

Nowadays, the use of bimetallic laminates with special capabilities and features is increasing and has experienced high growth. These properties include high mechanical properties, corrosion resistance, light weight, resistance to noted good abrasion and thermal stability. In the midst of the technologies of multilayer composite materials Accumulative Press Bonding (APB) is one of the most common techniques for the production of multilayer composites. One of the most important aims for this choice is the press pressure, which can create a strong and suitable mechanical connection between Produced metal layer components. In this study, the Accumulative Press Bonding method has been used to produce aluminum and copper composites and the process modeling has been done by ABAQUS finite element analysis software. In this paper, the effect of Press parameters such as strain and number of layers on the distribution stress of forming this type of composites has been investigated. Shear stress among the layers reached to about 4MPa for samples with eight layers which is a good condition to generation a successful bonding.  With increasing thickness, the stress applied on the layers has also increased. Maximum stress also increases significantly. As the thickness decreases, the interlayer shear stresses also increase. With increasing percentage of thickness decrease, the amount of sinking of the layers in each other has greater than before, which has led to the crushing of copper layers along the entire length of the sample. During the process, as the number of passes increases, the volume of virgin material in the direction of the press rises, which leads to increased compaction and better adhesion of the layers to each other.

In this article, free and forced vibration analyses of 3D printed FG sandwich beam based on higher order beam theory is investigated. The core and face sheets of sandwich beam are integrally fabricated by 3D printer. Therefore, ignoring the delamination between face sheets and core is a correct assumption. Three different cells are considered for the core including Re- entrant auxetic cell, anti-tetrachiral auxetic cell and conventional honeycomb cell. These cells are arranged along the thickness of structure based on cell thickness in four various patterns. The effective mechanical properties of cells are estimated by analytical relations. Finite element methods and Lagrange equations are employed for obtaining the effective stiffness and mass matrices of the sandwich beam. Finally, the influences of various parameters including various types of cells, various patterns of cell along the thickness of structure, thickness coefficient, the geometry of cells such as the interior angle and dimensions of cells on natural frequencies and transient deflection of structure have been studied. The results denote that the arrangement of cells along the thickness plays an important role on the vibration response of structure. On the other hand, for uniform thickness distribution of cells, Re –entrant auxetic cell has higher natural frequencies than other cells while in FG arrangements of cells, anti-tetrachiral cell with pattern A has higher natural frequencies than Re-entrant auxetic cell.

In this article, shear buckling analysis of functionally graded porous annular sector plate reinforced with graphene nanoplatelets (GPLs) are investigated for the first time. The plate is consisting of a layered model with uniform or non-uniform dispersion of graphene platelets in a metallic matrix including open-cell interior pores. The extended rule of mixture and the modified Halpin-Tsai models and are employed to obtain the effective mechanical properties of the porous nanocomposite plate. Three different porosity distributions in conjunction with five patterns for dispersion of GPL nanofiller are considered through the thickness of plate. Governing equations derived according to the principle of minimum total potential energy based on 3D elasticity theory and generalized geometric stiffness concept. Finally, finite element method is applied for solving the governing equations of structure. The influence of different parameters including various porosity distribution, porosity coefficient, patterns of GPL dispersion, weight fraction of GPL nanofiller, boundary conditions and sector angles on shear buckling loads of the annular sector plate has been surveyed.

An analysis is carried out on the natural or free convective magnetohydrodynamic flow of a non-Newtonian Jeffrey fluid with a Hall current, heat source, and variable suction near vertical plate.Using a flexible, widely validated variable finite element method, the governing nonlinear partial differential equations be transformed into linear partial differential equations using similarity variables, and this equations along with the associated boundary conditions be then solved numerically.The fluctuation of important parameters in the thermal and hydrodynamic boundary layers be thoroughly examined, and the findings are displayed visually. Additionally, a comparison study is offered to reduce verification and arrive at a excellent consensus. This model is beneficial for geothermal reservoirs, subterranean power transmission, MHD pumps, accelerators, and flow metres, as well as industrial heat management, geological flows within mud cover, etc.

In this research article is investigated by experimental and analytical (FE modeling with ANSYS) for T welded joints under tensile test. The SEM and EDS methods were applied for failure surface of welded joint. 3D model of welded joint was developed by using ANSYS software and simulated. The deformation of welded joint model in ANSYS was validated by using performing experiment. The fractography study is carried out with the help of scanning electronic microscope (SEM) method. It is observed the brittle and ductile fracture surface at heat affected zone. The chemical composition was found using DSE method, the experimental outcomes represented that the T-joint is much stronger than the corner joint. ANSYS results are much closed to the experimental results. FE model is created by using SOLID187 elements. The stress sanguinity at junction of T-welded joint was studied. Stress singularity decreased with increasing load The systematical examine failure surface of welded joint by using SEM method T-type of welded joint is very stronger that other joint as, Butt, Lap and Corner joint. Failure load of present model is 30KN is suggested by designing the military aircraft structure.

This research studied different tools with different cone angles to produce brass wires using the friction stir back extrusion (FSBE) method. The cone angle of the tool is one of the most influential parameters in the production of brass wires. First, to determine the appropriate cone angle, the FSBE process is modeled using the Coupled Eulerian-Lagrangian (CEL) method. The simulation results showed that increasing the cone angle increases the heat generated and reduces the force on the tool. Also, to be more precise, the mechanism of heat production during the process was numerically modeled to verify the simulation results. The cross-sectional images of the wires produced showed that only tools with a cone angle of 35 ° could produce flawless wires. The microstructural results showed that the grain size in the center of the wire was 20.24 microns, which is larger than the size in the wire periphery, which was 16.88 microns. This microstructural deviation is mainly affected by the strain and the temperature.

In any case, macroscale shaping cannot be transferred to microscale due to the size effect. There are different parameters to evaluate small-scale forming. In this article, the effect of flow stress and topography in two states of lubrication and without lubrication for T2 copper micro cylinder has been investigated using the numerical solution and prediction of a trained neural network. An artificial neural network model has been presented to investigate the flow stress and the effect of friction with the miniaturization of the copper microcylinder. The results show that the flow stress decreases with decreasing the initial specimen diameter in both lubrication conditions, and the flow stress decreases by 30 MPa with the initial specimen diameter decreasing from 8 mm to 1 mm. The friction factor increases obviously with decreasing the initial specimen diameter in the case of lubricating with castor oil, and the friction factor increases by 0.11 with the initial specimen diameter decreasing from 8 mm to 1 mm. However, the tribology size effect is not found in the case without lubrication. The reasons for the flow stress and tribology size effects were also discussed. The good matching of outputs and objectives in the regression graphs shows that the response of the neural network is satisfactory.

The behavior of various CNT distributions with agglomeration effects on FG plates is investigated in this paper under static loading. Here, to model the FG plate third-order shear deformation theory has been used and a FEM code has been developed. In the current higher-order shear deformation theory, transverse shear stresses are represented by quadratic variation along the thickness direction, resulting in no need for a shear correction factor. The properties of randomly oriented nano-inclusions are estimated using the two-parameter agglomeration model of Eshelby-Mori Tanaka. Next, the present approach is implemented with the FEM by employing a C0 continuous isoparametric Lagrangian FE model with seven nodal unknowns per node. The static response of CNT reinforced composite plate with the influence of inclusions is explored by altering the agglomeration parameters and through-thickness CNT distribution pattern. The obtained results suggest that ignoring the agglomeration effect on CNT may result in erroneous results for various static responses. Since the author could not find any results in the static response of CNT-reinforced plates with the agglomeration effect, the proposed model is validated with the results corresponding to the isotropic plate. The impact of several agglomeration phases on the static behavior of a square plate is then studied parametrically.

In this study, dynamic analysis of functionally graded carbon nanotube reinforced composite (FGCNT) beam resting on viscoelastic foundation is investigated. Four different types of carbon nanotubes (CNTs) distribution including uniform (UD-CNT), and three types of functionally graded distribution of CNTs through the thickness of beam are considered. The Kelvin–Voigt viscoelastic model and higher-order shear deformation beam theory (HOBT) have been used. The rule of mixture is used to describe the effective material properties of the nanocomposite beams. The equations of motion are derived by using Lagrange’s equations, and solved by using finite element and Newmark methods. The effects of volume fraction and distribution of CNTs, stiffness and damping of viscoelastic foundation, slenderness ratio and different boundary conditions on transverse displacement and stresses of beam are investigated. The results show that by using viscoelastic foundation the amount of normal and shear stress have decreased considerably, and by increasing the stiffness coefficient of foundation, transverse displacement of beam reduces and the frequency of vibration increases as well, meanwhile by increasing the damping coefficient of foundation, amplitude of vibration decreases considerably. The model is verified and compared with previously published works and it shows good agreement.