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The effective design of structures resistant to seismic vibrations is one of the main concerns of structural engineers to deal with damages caused by earthquakes, which can withstand more earthquake forces with methods such as energy dissipation. Recent earthquake records show that the earthquake record characteristic of the near area differs from the earthquake records of the far area. Among these characteristics, it can be mentioned that the pulse-type state of these records, as well as the high maximum speed and ground displacements. For this reason, these types of records increase the seismic requirements of the structure compared to normal earthquakes. The map of faults and seismic zoning of Iran shows that important urban points such as Tehran, Tabriz, etc. have high seismicity and are located near the fault. Therefore, it is necessary to design and build structures that can properly withstand the features of near-fault earthquakes, this issue reveals the understanding and recognition of the behavior of structural systems and the structure's response to the special features of near-fault earthquakes. This article first investigated the seismic evaluation of three existing 4, 8, and 12-story steel structures with lateral load-resisting systems. Then the desired structure was strengthened using a friction damper, and finally, the acceleration recorder was applied to the structure in the near- and far-fault earthquake zone case study. The seismic demand of the retrofitted structure was investigated in ANSYS Workbench finite element software, which was done in the form of modal analysis, floor drift displacement, structure acceleration response, and von Mises stress. For seismic validation, a two-story, single-span steel frame has been used. The dynamic load used was 0.5g based on the north-south component of the El Centro earthquake (1940) with a maximum acceleration scaled to 50 cm/s. To validate the numerical results, the horizontal displacement of two points on the first and second floor was compared with experimental data, and an acceptable accuracy was obtained. The results of the maximum acceleration at the highest point of the building showed that in a far-fault earthquake zone, the best effect of dampers was on 8-story buildings with a 77% decrease, and in a near-fault earthquake zone, it was related to a 4-story building with a 66.4% decrease in acceleration. Stress in near- and far-fault earthquake zones, the best effect of dampers was on 4-story buildings with 83% and 84% reduction, respectively. In a far-fault earthquake zone, the best effect of dampers was on 8-story buildings with a 44% reduction in maximum displacement, and in a near-fault earthquake zone, it was related to a 4-story building with a 61% reduction in acceleration.
 

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Steel plates are widely used in various industries, especially in civil engineering. Low cost in implementation and reduction of seismic mass are the advantage of steel shear wall system compared to other structural systems. The goal of a good design is that along with following the existing guidelines and achieving the desired seismic resistance of the structure, the structure is affordable in terms of weight and cost. Considering that according to the design, it is not possible to achieve the optimal use of the structure's capacity by force control method, the theory of uniform deformations was proposed with the assumption of a constant performance level. The subject of design based on performance increase the safety of the structure against earthquake force and design with optimal seismic performance during the useful life of the structure in seismic areas. Also, compared to the design method based on force control, it can lead to a lighter and economical design.
One of the significant ways to reduce the weight and stiffness of shear walls and boundary elements connected to them is to limit the connection of filler plates to boundary elements. In this method, limiting the length of the connection reduces the force on the beams and columns, and as a result, smaller sections can be used.
In this research, in order to achieve the optimal performance level, two concrete frames with steel shear wall resistant system are subjected to nonlinear analysis. Then, the initial evaluation of the behavior and the correctness of the used method are checked. After that, the effective factors in achieving uniform stress in the height of the structure will be investigated. For this purpose, by using the effect of the thickness parameter and the appropriate pattern of connection of the shear steel plate to the surrounding elements, the way of changing the performance and behavior of the structure will be investigated. For this purpose, 3- and 4-story concrete frames with steel shear wall systems were modeled using ABAQUS^TM finite element software. The steel used in the steel shear wall system is ST37. First, the connection of steel shear plates to floor beams was considered and then the influence of the partial connection pattern on the seismic performance of the steel shear wall system was investigated. The modeled frames were subjected to dynamic analysis, linear and nonlinear buckling analysis, and cyclic analysis. Based on the obtained results, the property of energy dissipation in the frame with a steel shear wall system with partial connection has increased significantly. Changing the partial connection pattern led to changing the maximum in-plan relative displacement. Also, the surface of the stress distribution shows that in the partial connection, the stress concentration mainly occurred in the place of the steel shear plate connections. In addition, according to the results of cyclic analysis, considering the partial connection of the steel shear wall has led to a decrease in the average energy absorbed in the structure and an increase in its ductility. Also, changing the connection pattern has affected the average amount of absorbed energy in different loading cycles.

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Low Intensity Magnetic Separators (LIMS) are widely used in research and industry. The design of this separator is based on drum rotation inside a tank media, so that a permanent magnets placing inside the drum as an angle form, produces a magnetic field. In this study, the behavior of magnetic and none-magnetic particles of a pulp, flowing through a magnetic field in the wet LIMS, was simulated and validated by experimental results. The magnetic field variables were calculated in an FEM based simulator (COMSOL Multiphysics); while particles’ tracking was done applying CFD numerical method, enhanced by discrete phase model (DPM). The difference between the results of the simulation and the magnetic separation experimental test (recovery of magnetic particles in the concentrate product) was 16.4%. In order to quantify the results of the simulation, magnetic separation simulation was performed by changing two variables affecting the magnetic separation process (variables of particle size of the input pulp feed particles and solid percentage of input pulp) and corresponding experiments. Comparison of laboratory and simulation results showed that the trend of simulation results is consistent with laboratory results of the weight recovery (in both variables under study), so that the maximum simulation error is related to the size of 125 microns (16.5 %) and the lowest simulation error was in 180 microns (11.4 %). Also, the lowest simulation error in the weight recovery prediction was related to the pulp feed solid percentage of 15% (equivalent to 14%) and the highest simulation error was in 30% pulp feed solid percentage (16.9 %). This proposes that FEM-DPM-CFD coupling model, can be applied for simulation, optimization, design and construct 

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In this research behavior of bubble due to under water explosion and it’s effects on ship structure have been studied. For determination of these effects field equations must be derived and solved them by mathematical simulation. Mathematical model is com in follow, it show physical rules on impression of bubble oscillation on body ship. This model is solved by combination of Euler method, 5 step Adams-Beshforse method and 4 step Adams-Moltone method for explaining the response of ship structure due to oscillation bubble. In order to agreement of solution way, stress-strain curves that obtained in this paper, is compared with experimental results. Also this results compared with FEMA results. Ship structure is modeled in ANSYS software in free beam form with variable mass and stiffness elements. Internal ship’s equipments and buoyancy are modeled by local mass and spring. The effect of explosion depth and explosive mass on stress in ship structure is studied. These result show when explosion depth is increased, stress is decreased and when explosive mass is increased, stress is increased.

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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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In this paper, we report results of stress analysis and fatigue life assessment of a number of spot weld joints. Models are presented for corrugated plates, jointed to an L-shape plate using 7 and 14 spot welds, which are subject to four different types of alternating loading conditions. The analyses are based on the solutions obtained from the ANSYS7 finite element package, using solid elements. In this study, strains and stresses in the weld nugget are evaluated. However, the primary focus is on strain-based fatigue life assessment which considers the 3D state of stress around the weld nugget and the nonlinear effects of the materical and the geometry.

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In this paper, we report results of stress analysis and fatigue life assessment of a number of spot weld joints. Models are presented for corrugated plates, jointed to an L-shape plate using 7 and 14 spot welds, which are subject to four different types of alternating loading conditions. The analyses are based on the solutions obtained from the ANSYS7 finite element package, using solid elements. In this study, strains and stresses in the weld nugget are evaluated. However, the primary focus is on strain-based fatigue life assessment which considers the 3D state of stress around the weld nugget and the nonlinear effects of the materical and the geometry.

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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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The higher frequency transient signals generated as a result of a power system fault or disturbance provide the basis for an alternative approach to power system containing connectors and cables result in unsuitable operation of the system. However one major challenge is the need to ensure that the transients to be neutralized by electromagnetic compatibility (EMC) issues and cabling routes. This paper proposes novel method for optimal cable routings and connectors; a combinatorial design Algorithm, to choose the best path when two or more physical paths are available. The best path from EMC point of view can be chosen based upon various criteria such as monetary cost minimization, voltage drop and quality (electromagnetic compatibility) parameters. This paper initially provides a numerical 2D and 3D resolution of the problems of radiation generated by current sources. The approach is based on the finite element method (FEM) associated with absorbing boundary conditions. The presented model makes it possible to consider wave propagation and their effects in heterogeneous mediums in transient which can be applied in EMC for the simulation of radiation. First, the formulations of the electromagnetic problem are detailed. The simulation results are used for the cabling routes with respect to undesirable field distribution in the specified regions. Finally by the use of AHP optimal routes for cabling based upon the above mentioned criteria are chosen. The proposed method is successfully implemented on two different types of power systems, "high voltage substation and current injection system".

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A non-linear finite element model could be a useful tool in the development of a method of predicting soil pressure-sinkage behaviour, and can be used to investigate and analyze soil compaction. This study was undertaken to emphasize that the finite element method (FEM) is a proper technique to model soil pressure-sinkage behaviour. For this purpose, the finite element method was used to model soil pressure-sinkage behaviour and a two-dimensional finite element program was developed to perform the required numerical calculations. This program was written in FORTRAN. The soil material was considered as an elastoplastic material and the Mohr-Coulomb elastoplastic material model was adopted with the flow rule of associated plasticity. In order to deal with material non-linearity, incremental method was adopted to gradually load the soil and a total Lagran-gian formulation was used to allow for the geometric non-linear behaviour in this study. The FEM model was verified against previously developed models for one circular footing problem and one strip footing problem and the finite element program was used to pre-dict the pressure-sinkage behaviour of the footing surfaces. Statistical analysis of the veri-fication confirmed the validity of the finite element model and demonstrated the potential use of the FEM in predicting soil pressure-sinkage behaviour. However, experimental verification of the model is necessary before the method can be recommended for exten-sive use.

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Abstract There are numerous applications for gas turbine discs in the aerospace industries such as in turbojet engines. These discs normally work under high temperature while subjected to high angular velocities. Minimizing the weight of such items in aerospace applications results in benefits such as low dead weights and lower costs. Optimization of rotating discs is historically, an area of research due to their vast utilization in industry. The gas turbine disc is one of examples to name. Gas turbine discs work mostly at high temperature gradients and are subjected to high angular velocities. High speed results in large centrifugal forces in disc and simultaneous high temperatures reduces the disc material strength, thus the later increases stress in disc automatically. In order to obtain a reliable disc analysis and arrive at the corresponding correct stress distribution, solution should consider changes in material properties due to the temperature field throughout the disc. To this end, an inhomogeneous disc model with variable thickness is considered. Using the variable material properties method, stresses are obtained for the disc under rotation and a steady temperature field. In this paper this is done by modeling the rotating disc as a series of different rings with constant properties. The optimum disc profile is arrived at by sequentially proportioning the thickness of each ring to satisfy stress requirements. In this paper these are done using the simplex method. Simplex algorithm is applied in Ansys software and the results are presented.

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In this study, pulsating hydroforming of tube in a box die is simulated using the three dimensional finite element method to investigate the mechanism of improvement of the corner filling. In addition, the results obtained from the simulation are compared with experimental observations, and the validity of the simulation results is verified. Based on a better understanding of the mechanism of improvement of the corner filling, a new pulsating pressure path is proposed to increase the corner filling. It has been shown that the proposed pulsating pressure path is more effective in increasing the corner filling of the box shape tube hydroforming process.

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Fine-blanking is an effective and economical shearing process which offers a precise and clean cutting edge finish, eliminates unnecessary secondary operations and increases quality. Fine-blanking process utilizes triple-action tools: a punch, a stripper with an indented V-ring and a Counter punch (ejector) to generate a highly compressive stress state. The deformation is more violent and localized than that of any other metal forming operations. Therefore it is difficult to fully understand the mechanism of the process. This study investigates the effect of V-ring indenter, clearance of die, Force of holder and Counter punch, etc on state of stress, quality and accuracy of production. Some parameters have both positive and negative effect on quality of production and the life of the tool. Utilizing V-Ring indenter in Die will increase quality of production and life of the tool. Also Artificial Neural Networks was used to simulate Fine-Blanking process. It has been shown that booth of FEM and ANN is suitable for simulating and forecast of effect of the parameters on production.

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bstract The average behavior of composite material like masonry can be described in terms of the relation average stresses and strains (macro model) if the material is assumed to be homogeneous. The average stress-strain relationship can be determined generally using two approaches. A possible approach is experimental investigation from the available experimental data. Another approach, adopted in this resedrch, is to develop a linear homogenization technique, which describes the behavior of the masonry from the geometry and the behavior of the representative basic cell. In this research, the elastic properties of a basic cell in masonry with a periodic arrangement of blocks were obtained based on a local stress field approach (micro-modeling of the mortar and blocks).Two different methods were used for computing the equivalent orthotropic elastic properties of the basic cell as a continuum, the approximate energy method (a closed form solution) and the finite element based method. The finite element method was used to approximately find the orthotropic yield curves of the homogenous element. The similarity of the general behavior of these gied curves with regard to the experimental facts was considerable.

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Tubular components, such as stepped tubes, conical tubes and box-shape tubes, are mainly produced by tube hydroforming process. Obtaining a sharp corner is the main goal in some of these components. In this paper, corner filling in stepped tubes is studied using a new multistage hydroforming die. The proposed die was simulated and filling of the die cavity was investigated. The finite element software, ABAQUS 6.4, has been used for simulation. In order to verify the simulation results, the new die of stepped tube was manufactured and then experiments have been performed on it. The results of the experiments verified the simulation results. It was shown that by using the new die, parts with sharp corners could be produced. The simplicity of the die and the low internal pressure are among the advantages of this die.Thickness distribution was also examined by FE simulation and via experiments and it is shown that a better distribution could be obtained by the proposed die set.

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Condition monitoring of BLDC motors due to their important applications is gaining more and more significance. Rotor eccentricity is one of the most important sources of faults in these motors. Up to now, detection methods of this fault under nonstationary conditions are limited to complicated and time-consuming methods using wavelets and Cohen class algorithms which are difficult to implement and need heavy computations to run. In this paper a novel method based on the modified Motor Current Signature Analysis method is proposed to detect the rotor eccentricity fault of BLDC motor operating under varying speed conditions. Stator current of healthy and faulty motor which are modeled by the Finite Element Method are simulated. By changing the representation of stator current from time basis to angle basis, the current signal will become stationary. Thus there is no need for methods using time-frequency analysis. Afterwards the Order Analysis Method is applied to the simulated healthy and faulty angle-based current signal and the results are compared with each other. Finally, the fault is detected by this comparison.

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Residual stress measurement is one of the most interesting research areas in experimental mechanics. Residual stress is introduced to material due to plastic deformation of parts and can be one of the most effective parameters on design and operation of parts. ASTM E837-01 standard studies residual stress determination in parts by hole drilling method and represent calibration coefficients for flat sheets with constant stress profile. However, there is no certain standard on the residual stress measurement by Incremental Hole Drilling Method (IHDM) which is the subject of this study. IHDM can obtain stress profile by using two modified stress calibration coefficients. In this article, the stress calibration coefficients have been extracted for incremental hole drilling by using finite element analysis (FEA). FEA contains both biaxial tension test and pure shear test which a hole has been drilled step by step in the parts by removing elements and the strains changes were determined at three strain gauge positions on the surface. At last, the calibration coefficients are determined for each step and the accuracy of coefficients have been verified by a set of experimental test and a FE analysis. The experimental test contains four-point bending of an AA5056 flat aluminum sheet. The numerical analysis contains four-point bending of a flat sheet. In both cases, the stress profile can be determined easily by using analytical equations. Average analytical stress in each increment has been calculated and compared with the result of numerical incremental hole drilling method. The comparisons show that numerical and experimental results have no significant differences in first six steps but in the last four steps show an increasing errors due to the change in stress profile and hole geometry. Results presents that the calibration coefficients have suitable accuracy in stress profile determination.

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Aluminum alloys are desirable in industry due to their excellent high-strength to weight ratio, corrosion resistance, and weldability. However, at room temperature, the formability and the surface quality of the final product of these alloys are low. So in recent decade, new process, hot metal gas forming, has been introduced. This paper investigated new method of hot aluminum alloys forming using gas. Experimental test for bulge forming was designed and made. In addition to experimental test, finite element analysis of process was done. Results showed that hot metal gas forming provides highest forming temperature for aluminum alloy blank and with increasing blank temperature up to optimum temperature of hot forming, there is reduced pressure forming and significant improvement of formability. Results of experimental test and finite element analysis including determination of optimum temperature for forming of special aluminum alloy, maximum formability in this process, required forming pressure, minimum thickness, thickness and temperature distribution were conformed.

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In this paper torque ripple in switched reluctance motor is studied. The presented method in this paper for minimization of torque ripple is based on suitable machine structure obtained from the genetic algorithm (GA) and suitable machine driver. In the presented paper, the parameters of one machine are chosen as the reference machine parameters. Then some parameters of machine are chosen, which have no effects on the characteristics of mechanical, power and volume of reference machine. The desirable machine is simulated by finite element software, and then the torque characteristics are obtained for different machine structure with various machine parameters. Finally, with GA the best parameters for the design of machine with minimum torque ripple are chosen. So this paper presented for the first time an accurate method by finite element method in the process of machine design by GA. The finite element method used in the previously studies in the design of machine only for machine analysis, but in this paper finite element method is used in the process of machine design. So this method of machine design can be replaced to a conventional method. In this paper, the design of SRM driver is presented based on the best machine structure which is chosen from GA. So, the profile of machine torque for this structure has minimum deviation from the ideal torque without the ripple