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In this paper comparison of finite element results and experimental observations of the hydroforming deep drawing is considered in which fluid pressure is used instead of die. Effects of hydroforming parameters during the process are studied, and a comparison with conventional method in deep drawing of aluminum alloys sheets with different blank diameters is presented. Large strain effects, anisotropic material properties, and the Coulomb friction theory in contact surfaces have been considered. ABAQUS code was used for simulation of process. In the first step, the numerical results have been verified by available experimental results, which showed a good agreement. These results contain force-punch travel and thickness strain. In the next step, the effects of initial pressure, friction, and punch radius on wrinkling, tearing, earring, and thickness strain have been studied. The results showed the range of pressure container for the hydroforming deep drawing. A comparison between some of the common deep drawing methods has been presented based on two main failure criteria and thickness strain criteria. Finally it is concluded that the hydroforming process is a more efficient method for achieving the higher drawing rate with respect to the conventional methods.

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A laboratory dryer used for a thin layer of  165 g Thompson orange slices with three thickness levels of 2, 4 and 6 mm, five different temperatures of  40, 50, 60, 70 and 80 °C and three air speed levels of 0.5, 1 and 2 m/s were employed to find the best dried and minimum energy consumption. This experiment was done in a complete randomized block design with the factorial treatments performed in three replicates. The energy consumption for drying thin slices of orange was calculated accordingly. The analysis of results showed that the lowest and highest drying energy consumption were 3.35 kWh (for 2 mm slice thickness and 40 °C)  and 15.2 kWh (for 6 mm slice thickness and 70 °C), respectively.

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In this paper comparison of finite element results and experimental observations of the hydroforming deep drawing is considered in which fluid pressure is used instead of die. Effects of hydroforming parameters during the process are studied, and a comparison with conventional method in deep drawing of aluminum alloys sheets with different blank diameters is presented. Large strain effects, anisotropic material properties, and the Coulomb friction theory in contact surfaces have been considered. ABAQUS code was used for simulation of process. In the first step, the numerical results have been verified by available experimental results, which showed a good agreement. These results contain force-punch travel and thickness strain. In the next step, the effects of initial pressure, friction, and punch radius on wrinkling, tearing, earring, and thickness strain have been studied. The results showed the range of pressure container for the hydroforming deep drawing. A comparison between some of the common deep drawing methods has been presented based on two main failure criteria and thickness strain criteria. Finally it is concluded that the hydroforming process is a more efficient method for achieving the higher drawing rate with respect to the conventional methods.

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Completion and development of reliable analytical models using finite element method could help investigation and prediction of the actual structure response results. Analysis of each model in finite element software needs meshing, in which computer results are dependent specifically to geometry and dimensions of the elements, called "mesh dependence". Finding a strategy for independency of the results to meshing is tangible. For the mentioned purpose and also to investigate the role of finite elements meshing in flanged shear walls, finite element software was used. Different meshings of shear walls (tested by Vecchio and Palermo) were analyzed and studied. The results of analyses with different meshs showed different ultimate strengthes and lateral displacementes. Different shapes of mesh create various results, which are indicated in the finite element model. By increasing of the size of mesh, the final force was increased and the lateral displacement was decreased, which presents a rigid model. On the other hand, by decreasing of the dimension of mesh, a stiff model was seen. So, it is a need to create well proses to analyze and evaluate the flanged section of shear walls with finite element model. Getting suitable accuracy of finite element model, the mentioned concrete shear wall (vecchio and Palermo) was modeled by ANSYS. 3D SOLID65 element was employed for modeling of shear wall structures. This element is capable of cracking in tension and crushing in compression. In concrete applications, for instance, the solid capability of the element may be used to model the concrete while the rebar capability is available for modeling of reinforcement behavior. After calibration, optimum forms and dimensions are recommended. As an illustration, an idea was presented, by which flanged shear wall could be analyzed more carefully in ultimate strength and ductility. This analysis showed that the results of squared mesh are closer to the fact. For example, this type of meshing 6% error in ultimate strength and ductility in accordance to lab Specimen, presented the closer responses. Furthermore, investigation on the optimum size of the mesh showed that if the mesh has the same size of the thickness of the connecting element (Shear Wall Web), the results will have very high accuracy. For instance, squared meshes with same dimension of meshes equal to web thickness, rather than those with half dimension of that led to 1% of lateral resistance, which is closer to experimental test. It is possible that web thickness is 150 mm, thereby, we can use mesh sizes of 150mm, 75mm or 50mm. However, in order to obtain ultimate loads accurately, the mesh size of 150mm seems reasonable. Square meshes have four degrees of freedom. If the size of square is chosen to be the same as the web thickness, nodal forces induced in the web would be proportionate. For thischallenge, a flanged section reinforced concrete shear wall tested was selected to confirm the web thickness square theory. This shear wall was modeled by finite element program. The results of analysis showed accuracy in the investigated theory. In this study, the web thikness square theory has indicated 8% error in ultimate strength.

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Drying process is influenced by a variety of parameters including the geometry of part being dried. To evaluate the effect of part geometry on drying process, and resultant defects, the process is analyzed and studied. Based on the assumption related to the porous media the governing equation of the mass transfer and static equilibrium are presented. The mechanical stresses generated by the drying strains are expressed according to the linear-elastic model. Dependence of physical and mechanical properties such as Young's modulus and diffusion coefficient as a function of moisture are considered in simulation for a chemically known ceramic material. it’s Assumed that Extended thin film evaporation is the mechanism of evaporation in constant rate period has been studied. The Von Misses criterion is used for crack anticipation in 2D and 3D drying. A significant difference was observed in possibility of crack initiation for the two different configurations. Yield stress in hygroscopic moisture has been determined experimentally. Developed model made it possible to predict the time and the place of crack initiation. Different part thicknesses were studied to examine the effect of thicknesses variations on cracking. It is observed that the danger of cracking is highest at the beginning of the drying, since the yield stress is low.

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In this research, the effects of different parameters on simulation of Young’s modulus of a Graphene sheet are studied. In simulation of Young’s modulus of Graphene sheet, different parameters such as the thickness of a single layer of Graphene, type of loading and boundary conditions, effects of interactions non-neighbor atoms, type of element for carbon-carbon bond, mechanical properties of carbon-carbon bond and the size of the Graphene sheet influence the results. It was found that the thickness of a single layer Graphene and the type of element are effective parameters. Moreover, the type of loading and boundary conditions did not influence the Young’s modulus of the Graphene sheet. Therefore, the Graphene sheet can be considered as an isotropic material. Considering the effects of interactions of non-neighbor atoms increases the run-time and improves the accuracy of calculations. Mechanical properties of carbon-carbon bond are important parameters and must be chosen carefully. Also, it has been observed that when the length and width of the Graphene sheet are smaller than one nanometer, the size of Graphene sheet has a great influence on the Young’s modulus.

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In this paper, the thermal buckling behavior of circular plates with variable thicknesses made of bimorph functionally graded materials, under uniform thermal loading circumstances, considering the first-order shear deformation plate theory and also assumptions of von Karman has been studied. The material characteristics are symmetric to the middle surface of the plate and, based on the power law, vary along with thickness; where the middle surface is intended pure metal, and the sides are pure ceramic. In order to determine the distribution of pre-buckling force in the radial direction, the membrane equation is solved using the shooting method. And the stability equations are solved numerically, with the help of pseudo-spectral method by choosing Chebyshev functions as basic functions. The numerical results in clamped and simply supported boundary conditions and the linear and parabolic thickness variations are presented. And the influence of various parameters like volume fraction index, the thickness profile and side ratio on the buckling behavior of these plates has been evaluated.

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In tube hydroforming process, due to friction condition, uniform wall thickness, as well as sharp corners may not be achieved. Use of ultrasonic vibration can improve the contact conditions at the tube-die interface. The current work studies the effect of applying ultrasonic vibration on wall thickness and corner filling of hydroformed tubes. Firstly, a numerical model based on geometric relationships and stress-strain state has been established by which wall thickness and corner radius of hydroformed tubes can be obtained. In this model, the ultrasonic vibrations affect the nonlinear friction conditions at the tube-die interface. By comparing the FEM models of tubes in two cases of with vibration and without vibration, it is possible to investigate the effects of vibration on wall thickness and corner filling. The results indicate superimposing ultrasonic vibrations to the process will increase corner filling ratio of the tube significantly, and more uniform tube wall thickness will be achieved.

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Water-storage capacity of reservoir reduces mainly due to sediment laden. Turbidity current has an important role on sediment transfer in reservoir. It is necessary to study sediment interaction and flow in order to predict mechanism of turbidity current. In this paper effects of changes in entrance hydraulic condition of turbidity current on head velocity, layer-average thickness, layer-average velocity, body velocity and turbulent structure have investigated experimentally. The front velocity of the head of turbidity current was determined by video recording and body velocity and turbulence parameters measured by Vecterino. When the initial Froude number decreases the maximum velocity increases in body and head. Positive shear Reynolds stress near bed indicates that major contributor in this region is sweep or ejection while major contributor near interface is inward interaction or outward interaction. Entrainment is dominated at interface. The investigation shows that head velocity depends on inlet Froude number and inlet Reynolds number. Variation of head velocity along channel is exponential. The maximum reduction of head velocity takes place at  whereas variation of head velocity at  is negligible. Driving forces at  are inertial force and gravity force. Driving force decreases after hydraulic jump and only gravity force remains as driving force. Therefore head velocity is constant at . Head velocity increases when inlet Reynolds number increases. Body velocity increases when inlet Froude number decreases, as gravity force increases when inlet Froude number decreases. Effects of inlet Froude as number on body velocity is negligible at the end of channel. Negative value of body velocity at the interface of turbidity current and ambient fluid indicates entrainment phenomenon at this region. When inlet Froude number decreases, vertical component of velocity increases too,then maximum velocity approaches to the bed. Elevation of maximum velocity increases along the channel due to sedimentation of particles and decreases of vertical component of velocity. Body velocity decreases along the channel due to decrease of inertial force. Vertical Reynolds stress decreases when inlet Froude number decreases. Because of increase in particle turbulence dissipates and therefore vertical Reynolds stress decreases. Oscillation of vertical Reynolds stress is due to turbulence at this region. The maximum of vertical Reynolds stress tacks place near bed and interface of turbidity current and ambient fluid and minimum of vertical Reynolds stress tacks place near maximum velocity elevation. Shear Reynolds stress have two maximum values. One is near the bed and the other one is near the interface of turbidity current and ambient fluid. Maximum Reynolds shear stress is positive near bed and negative near interface. Minimum of Reynolds shear stress take place near maximum velocity elevation.

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Calculation the cutting force in machining processes is of great importance. In this paper, undeformed chip thickness in one-dimensional ultrasonic vibration assisted milling is calculated and then, a model for determining the cutting force in this process is presented. Analytical relations show that in ultrasonic assisted milling (UAM), the maximum cutting force is greater than in conventional milling (CM), but the average cutting force is decreased. To verify the proposed relations, with the aid of a particular experimental setup, one-dimensional vibration in feed direction is applied to workpiece and cutting force in CM and UAM is measured experimentally. Greater maximum cutting force in UAM and decrease of average cutting force in UAM compared to CM is observed experimentally as well. Comparison of average values of cutting force shows that the analytical relations for predicting the cutting force have 16% average error in CM and 40% average error in UAM. Given that the analytical calculation of undeformed chip thickness and cutting force in UAM and also comparison of experimental forces with the modeled ones has been done in this paper for the first time, the accuracy of proposed relations are acceptable.

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Gears are one of the most important elements of any power transmission system. Among all types of gears, helical gears are more common due to their high capacity in power transmission as well as lower level of noise. The aim of this study is to present a model for analyzing the contact of teeth of helical gears considering thermal effects and surface roughness. In the present model, each helical gear is divided to several narrow spur gears in which each of the spur gears have a small rotation angle relative to the previous one. Also each contact point of gears is replaced with contact of two equivalent cylinders. Considering the fact that the governing regime for gears lubrication is the mixed-elastohydrodynamic regime, the total load is carried by lubricant and asperities' contact. Meshing and lubrication analysis of a pair of helical gears is conducted based on the load-sharing concept and parameters such as film thickness, friction coefficient and temperature rise are predicted. The predictions based on the load-sharing concept are compared to other published results Acceptable accuracy, short execution time along with considering thermal and roughness effects are some of the major characteristics of this study.

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In this research, the plunging motion of an airfoil by a numerical method based on finite volume in different Reynolds numbers is simulated and the thickness effect, amplitude and reduced frequency on the aerodynamic coefficients are investigated. In this process, SIMPLEC algorithm, implicit solver, high order scheme and dynamic mesh method is used in unsteady simulation and the flow is supposed viscous, incompressible and laminar. Simulations are in three Reynolds 1000, 11000 and 50000, respectively, in accordance with the flight of the insects, small birds and pigeons are done in two amplitudes and three reduced frequencies. The simulation results are compared with published data to confirm the validity of research. This comparison shows comprisable agreement. Pressure distribution and Vortex shedding around airfoils show that the thickness of the airfoils delays vortex shedding and changes time-averaged thrust coefficient. Reduced frequency and amplitude of oscillation are two important parameters in this simulation, but the reduce frequency is more effective than amplitude. The response surface methodology (RSM) was used to optimize the plunging airfoil. Optimization shows that airfoil with 0.29% thickness, 3.08 reduced frequency and 0.5 dimensionless oscillating amplitude produce maximum trust coefficient.

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Lubrication is an essential factor in sheet metal forming processes such as deep drawing in order to reduce friction at contact surfaces, forming load, tool wear rate and increasing of sheet formability. Various metal oxide nanoparticles can be used as additives to create desirable tribological properties in base lubricants because of their unique properties such as specific surface area. In the present study, the conventional lubricant enhanced by alumina nanoparticles (Al2O3) is utilized in deep drawing process in order to improve frictional conditions. The forming load, surface roughness (Ra) and thickness distribution values of the formed cups were assessed to evaluate the performance of the enhanced conventional lubricant with alumina nanoparticles (Al2O3) in comparison to the conventional lubricant and dry forming condition. The obtained results from experimental tests revealed that adding 0.5 wt.% Al2O3 nanoparticles to the conventional lubricant improves lubrication property significantly and reduces forming load by 16.39% and surface roughness by 19.33% compared to the conventional lubricant. Furthermore, it is observed that using lubricant containing nanoparticle additives results in 23.94% improvement in maximum thickness reduction in critical zone.

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In this paper, elastic-plastic symmetrical buckling of a thin solid circular plate of variable thickness, under uniform edge pressure, is investigated, based on both Incremental Theory (IT) and Deformation Theory (DT). Two kinds of simply supported and clamped boundary conditions have been considered. A power-law function was assumed for thickness variation. To minimize the integral uniqueness criterion, based on Rayleigh-Ritz method, transversal displacement was approximated by a test function which includes some unknown coefficients and satisfies geometric boundary conditions. Substituting the test function in the stability criterion and minimizing with respect to the unknown coefficients results in a homogeneous algebraic set of equations in terms of unknown coefficients. For non-trivial solution, the determinant of coefficient matrix should be equated to zero. Using this equation, critical buckling load is determined. The results of present study were compared with existing analytical solutions for circular plate of constant thickness and a good agreement was observed. This clearly shows the validity of presented analysis. Then the effect of thickness variation and boundary conditions type on the critical buckling load was investigated, for commercial aluminum and steel 1403 materials. The results show that when the thickness of circular plate center is 10% greater than its edge thickness the buckling load may increase up to 40% comparing with the circular plate for which the center thickness is 10% less than its edge thickness.

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Aluminum alloys have high strength to weight ratio and Poor formability at room temperature is the main drawback of using these alloys. In order to overcome this limitation, the work material is formed at higher temperature. One of the forming processes is hydrodynamic deep drawing on which no relevant research has been reported in warm condition. In the present paper, after examining the formability of 5052 aluminum alloy in warm hydrodynamic deep drawing, the effect of media pressure, temperature and forming speed on thickness distribution and punch force in forming of flat-bottom cylindrical cups was investigated. In order to perform a complete investigation, the simulation of the process was established using ABAQUS software. It was illustrated that the results was in accordance with the experimental findings. It was also demonstrated that increasing the maximum oil pressure to a specified level could improve the thickness distribution and lead to increasing the punch force. The required punch force was decreased with increase in temperature but remained unchanged by punch speed variation. The maximum thickness reduction was decreased with increasing and decreasing of temperature and punch speed, respectively. Moreover, the forming of the sheet at room temperature, isothermal and non-isothermal warm forming processes was compared. It was concluded that the maximum thickness reduction in the formed part was less in the cases of cold forming and non-isothermal warm forming than the isothermal warm forming. But the required forming force is decreased in isothermal warm forming when compared with the other two conditions.

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Forming media in metal forming processes is so important. Since the forming media in Ball deep-drawing process is discrete, it is quite flexible. In this paper, thickness distribution and required force for forming of conical part by ball deep-drawing and conventional deep-drawing processes using finite element simulation and experimental stages, were studied. In this research, sheets were used made St14 steel and brass wit 1mm thickness. The experimental results are in good agreement with simulation results. The results showed the sample formed by conventional deep-drawing process had more uniform thickness distribution than ball deep-drawing, but the maximum thinning in the parts of ball forming process was less than conventional deep-drawing process. Also it was observed that required force for ball deep drawing process is more than the conventional deep-drawing process. It was observed that with increasing radius of the input die, the force required to stretch the ball deep-drawing and ball processes is decreased, also with increasing radius of the input die is reduced thinning amount. It was noted that one of the advantages of ball deep drawing process than traditional deep drawing process is achieved a negative slope part.

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Cold spin bonding is a new invented method for producing layered composite tubes based on flow-forming process. Bonding strength in this process is dependent to parameters such as initial thickness, rate of deformation, bonding temperature, initial strength, heat treatment temperature, duration of heat treatment and also production parameters like feed rate and spindle RPM. In the present work, effect of rate on thickness reduction, heat treatment temperature and duration of heat treatment on bonding strength of steel and aluminum have been studied. The strength of bonding which produced by cold spin bonding has been measured by peel test and structure investigation has been done by scanning electron microscopy. Among the parameters, heat treatment temperature and after that thickness reduction rate have the most effects on bonding strength and heat treatment duration has less effect in comparison. The results show that the increase of heat treatment temperature up to a certain level increase bonding strength, but above that level the strength will decrease. . This study also has shown that the best condition occur in %50 thickness reduction, heat treatment temperature of 475 degree and 120 minutes of heat treatment in which bonding strength reaches to yield strength of base metal.

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Electrohydraulic forming (EHF) is a high velocity forming process in which the electric energy stored in the capacitors are suddenly discharged between two electrodes submerged in a water-filled chamber. During the discharge, the water between the electrodes vaporizes and creates a shock wave that is transferred to the blank using the water and forms it. One of the key parameters in electrohydraulic forming is the determination of the suitable position of the electrodes. In this research the effect of electrodes position in electrohydraulic free-forming is investigated using the finite element simulation. First the experiments available in the literature is simulated using the software ABAQUS/ Explicit and compared with the experimental results which shows good agreement with. Then by changing the position of the electrodes, the effect of their position on the formability and thickness distribution of the blank is investigated. The results indicates that the forming a component is only possible in limited positions of the electrodes and there is a position for the electrodes that not only improves the sheet thickness but also decreases the possibility of the failure.

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Metallic bipolar plate is one of the main parts of fuel cell. Several methods were used by researchers to manufacturing bipolar plate such as stamping, hydroforming and electromagnet forming. The effect of process parameters on dimensional accuracy of metallic bipolar plates in rubber pad forming process has been investigated in this study. ABAQUS/Standard finite element software is used to simulate the process. The accuracy of the results of simulation process is evaluated by using experimental results. To perform experimental procedures, rigid die with parallel flow field is used to form SS316 bipolar plate with 0.1 mm thick. For this purpose the effect of punch load, rubber hardness, rubber thickness and clearance between die and container on the dimensional accuracy of the formed parts is investigated. In this regard, rubber layer with hardness of 55, 70, 85 and 90 Shore A and thickness of 1.5mm up to 5.5mm were used. The result show difference between lateral and central channel depth, the amount of disparity will decrease by increasing in punch load, as a result the dimensional accuracy will increase. According to the result, increase in hardness and thickness of the rubber layer lead to improve the dimensional accuracy. Also considering clearance between die and container decrease the difference between lateral and central channel depth and eventually cause increasing in dimensional accuracy of formed part.

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Rubber pad forming is a practical and low-cost method of producing metal bi-polar plates with complicated multi- array contours since it only needs a rigid die and a flexible rubber. In this study, 316 stainless steel sheets with the thickness of 0.1 mm were used. To form the plates, a polyurethane rubber was used with the hardness shore of A 85 with the thickness of 25 mm. In order to increase the depth of the channel flow and form filling plates with a high depth-to-width ratio, firstly, the effects of lubricants on shaping metal plates were ignored. Subsequently, by implementing lubricants, their effects on achieving a higher filling depth and a more uniform thickness distribution were investigated. The results showed that in rubber pad forming process, lubricants could be used to further enhance the depth of filling and have a uniform thickness distribution in the channels of generated plates. Moreover, among available lubricants, polypropylene nylon will be the best alternative for the production of bipolar plates due to its high tensile strength and low thickness.