Finite element model

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1 - Simulation of Ultrasonic Welding of Al-Cu Dissimilar Metals for Battery Joining
Reza Abdi Behnagh Peyman Esmaeilzadeh Mohsen Agha Mohammad Pour

Ultrasonic welding is gaining popularity for joining of thin and dissimilar materials and foils in the fabrication of automotive Li-ion battery packs because of excellent efficiency, high production rate, high welding quality, etc. Precise control of the parameters of t أکثر

Ultrasonic welding is gaining popularity for joining of thin and dissimilar materials and foils in the fabrication of automotive Li-ion battery packs because of excellent efficiency, high production rate, high welding quality, etc. Precise control of the parameters of the welding process plays an important role in achieving good joint quality. Numerical simulation can greatly help control the main input parameters such as frequency, clamping pressure, friction coefficient, and vibration amplitude. In this present work, a three-dimensional thermo-mechanical Finite Element (FE) model is proposed using ABAQUS/EXPLICIT for the dissimilar Al to Cu weld to predict the deformation and temperature as output parameters during welding process by varying input parameters. The simulation results showed that the clamping pressure, vibration frequency and friction coefficient have a great influence on heat production during the process which was critical to determine the final quality of the welded joint. Studies also showed that increased clamping force and welding frequency led to increased deformation. تفاصيل المقالة

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2 - Numerical simulation of multilayer cellular scaffolds with 3D and 1D elements
Hamid Reza khanaki Sadegh Rahmati Mohammad Nikkhoo Mohammad Haghpanahi Javad Akbari

10.30495/admt.2020.1905314.1207

In this paper, an attempt has been made to provide a numerical method for investigating the mechanical properties of multilayer scaffolding. These scaffolds can be used as implants in bone fractures. For this purpose two numerical simulation methods are introduced to pr أکثر

In this paper, an attempt has been made to provide a numerical method for investigating the mechanical properties of multilayer scaffolding. These scaffolds can be used as implants in bone fractures. For this purpose two numerical simulation methods are introduced to predict the elastic properties of multilayer cell scaffolds. These simulations are based on two models: a 3D model with a volumetric element, and a 1D model with a linear element. To compare the results of these models, three types of two- and three-layer titanium alloy scaffolds have been simulated by the two methods. Also, Young's modulus of the scaffolds has been compared with the experimental conclusions of earlier studies. The results confirm that simulations with 1D models are more cost-effective compared to 3D ones. Additionally, because of the more reliable agreement of Young's modulus results of numerical modeling with the linear element (1.8 to 5 times) compared to the volumetric element (11 to 23 times) compared to the experimental findings, the numerical method with the linear elements can be a reliable tool for studying multilayer scaffoldings. تفاصيل المقالة

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3 - Influence of Addendum Modification Factor on Root Stresses in Normal Contact Ratio Asymmetric Spur Gears
R Prabhu Sekar R Ravivarman

10.22034/jsm.2019.664230

Tooth root crack is considered as one of the crucial causes of failure in the gearing system and it occurs at the tooth root due to an excessive bending stress developed in the root region. The modern power transmission gear drives demand high bending load capacity, inc أکثر

Tooth root crack is considered as one of the crucial causes of failure in the gearing system and it occurs at the tooth root due to an excessive bending stress developed in the root region. The modern power transmission gear drives demand high bending load capacity, increased contact load capacity, low weight, reduced noise and longer life. These subsequent conditions are satisfied by the aid of precisely designed asymmetric tooth profile which turns out to be a suitable alternate for symmetric spur gears in applications like aerospace, automotive, gear pump and wind turbine industries. In all step up and step down gear drives (gear ratio > 1), the pinion (smaller in size) is treated as a vulnerable one than gear (larger in size) which is primarily due to the development of maximum root stress in the pinion tooth. This paper presents an idea to improve the bending load capacity of asymmetric spur gear drive system by achieving the same stresses between the asymmetric pinion and gear fillet regions which can be accomplished by providing an appropriate addendum modification. For this modified addendum the pinion and gear teeth proportion equations have been derived. In addition, the addendum modification factors required for a balanced maximum fillet stress condition has been determined through FEM for different parameters like drive side pressure angle, number of teeth and gear ratio. The bending load capacity of the simulated addendum modified asymmetric spur gear drives were observed to be prevalent (very nearly 7%) to that of uncorrected asymmetric gear drives. تفاصيل المقالة

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4 - Nonlinear Finite Element Analysis of Bending of Straight Beams Using hp-Spectral Approximations
R Ranjan

Displacement finite element models of various beam theories have been developed using traditional finite element interpolations (i.e., Hermite cubic or equi-spaced Lagrange functions). Various finite element models of beams differ from each other in the choice of the in أکثر

Displacement finite element models of various beam theories have been developed using traditional finite element interpolations (i.e., Hermite cubic or equi-spaced Lagrange functions). Various finite element models of beams differ from each other in the choice of the interpolation functions used for the transverse deflection w, total rotation φ and/or shear strain γxz, or in the integral form used (e.g., weak form or least-squares) to develop the finite element model. The present study is concerned with the development of alternative beam finite elements using hp-spectral nodal expansions to eliminate shear and membrane locking. Both linear and non-linear analysis are carried out using both displacement and mixed finite element models of the beam theories studied. Results obtained are compared with both analytical (series) solutions and non-linear finite element solutions from literature, and excellent agreement is found for all cases. تفاصيل المقالة

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5 - A Comparative Study of Least-Squares and the Weak-Form Galerkin Finite Element Models for the Nonlinear Analysis of Timoshenko Beams
W Kim J.N Reddy

In this paper, a comparison of weak-form Galerkin and least-squares finite element models of Timoshenko beam theory with the von Kármán strains is presented. Computational characteristics of the two models and the influence of the polynomial orders used on أکثر

In this paper, a comparison of weak-form Galerkin and least-squares finite element models of Timoshenko beam theory with the von Kármán strains is presented. Computational characteristics of the two models and the influence of the polynomial orders used on the relative accuracies of the two models are discussed. The degree of approximation functions used varied from linear to the 5th order. In the linear analysis, numerical results of beam bending under different types of boundary conditions are presented along with exact solutions to investigate the degree of shear locking in the newly developed mixed finite element models. In the nonlinear analysis, convergences of nonlinear finite element solutions of newly developed mixed finite element models are presented along with those of existing traditional model to compare the performance. تفاصيل المقالة

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6 - Investigation of Vacancy Defects on the Young’s Modulus of Carbon Nanotube Reinforced Composites in Axial Direction via a Multiscale Modeling Approach
M.R Davoudabadi S.D Farahani

In this article, the influence of various vacancy defects on the Young’s modulus of carbon nanotube (CNT) - reinforcement polymer composite in the axial direction is investigated via a structural model in ANSYS software. Their high strength can be affected by the أکثر

In this article, the influence of various vacancy defects on the Young’s modulus of carbon nanotube (CNT) - reinforcement polymer composite in the axial direction is investigated via a structural model in ANSYS software. Their high strength can be affected by the presence of defects in the nanotubes used as reinforcements in practical nanocomposites. Molecular structural mechanics (MSM)/finite element (FE) Multiscale modeling of carbon nanotube/polymer composites with linear elastic polymer matrix is used to study the effect of CNT vacancy defects on the mechanical properties. The nanotube is modeled at the atomistic scale using MSM, where as the interface we assumed to be bonded by Vander Waals interactions based on the Lennar-Jonze potential at the interface and polymer matrix. A nonlinear spring is used for modeling of interactions. It is studied for zigzag and armchair Nanotubes with various aspect ratios (Length/Diameter). Finally, results of the present structural model show good agreement between our model and the experimental work. تفاصيل المقالة

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7 - Finite Element Instability Analysis of the Steel Joist of Continuous Composite Beams with Flexible Shear Connectors
H Bakhshi H.R Ronagh

Composite steel/concrete beams may buckle in hogging bending regions. As the top flange of I-beam in that arrangement is restricted from any translational deformation and twist, the web will distort during buckling presenting a phenomenon often described as restricted d أکثر

Composite steel/concrete beams may buckle in hogging bending regions. As the top flange of I-beam in that arrangement is restricted from any translational deformation and twist, the web will distort during buckling presenting a phenomenon often described as restricted distortional buckling. There are limited studies available in the literature of restricted distortional buckling of composite steel/concrete I-beams subjected to negative or hogging bending. There is none however that includes the effect of partial shear interaction. In this paper, finite element models for in-plane analysis and out-of-plane buckling of continuous composite I-beams including the effects of partial shear interaction are presented. تفاصيل المقالة

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8 - اصلاح مدل اجزاء محدود به روش تابع پاسخ (RFM)
محمدرضا آشوری حمید دائیان احسان جمشیدی

امروزه بدلیل پیچیده شدن طراحی ها، بررسی رفتار سازه های دینامیکی بکمک اجزاء محدود بسیار مورد توجه قرار گرفته است و با ظهور کامپیوتر های قدرتمند استفاده از این روش ها توسط طراحان با شتاب بیشتری صورت می گیرد. روش دیگر دستیابی به یک مدل دینامیکی برای سازه های مکانیکی، ساختن أکثر

امروزه بدلیل پیچیده شدن طراحی ها، بررسی رفتار سازه های دینامیکی بکمک اجزاء محدود بسیار مورد توجه قرار گرفته است و با ظهور کامپیوتر های قدرتمند استفاده از این روش ها توسط طراحان با شتاب بیشتری صورت می گیرد. روش دیگر دستیابی به یک مدل دینامیکی برای سازه های مکانیکی، ساختن مدل آزمایشگاهی برای سازه با انجام تستهای ارتعاشی و تحلیل داده های اندازه گیری شده می باشد. به این فرایند در اصطلاح تست مودال (Modal Testing) می گویند که در طی سه دهه گذشته در تئوری و عمل توسعه بسیاری یافته است. یکی از مهمترین کاربردهای تست مودال، بهبود مدلهای عددی سیستم های دینامیکی با مقایسه پارامترهای مودال حاصل از نتایج تست مودال و مدلهای عددی می باشد. پس از بهبود مدل عددی، می توان با اطمینان از آن در تحلیل های بعدی مانند پیش بینی پاسخ به یک نیروی وارده بر سازه، کوپلینگ سازه ها، تحلیل تنش و غیره استفاده کرد. در این مقاله مزایا، معایب و محدودیتهای یکی از روشهای امروزی بهبود مدل دینامیکی سازه ها بنام روش تابع پاسخ (Response Function Method) مورد بررسی قرار گرفته است. همچنین برای درک بهتر روش یک مدل 5 درجه آزادی جرم و فنر توسط نرم افزار MATLAB مدل گردیده است. تفاصيل المقالة

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9 - New Design of Mems piezoresistive pressure sensor
Hamsa Kamali Asghar charmin

The electromechanical analysis of a piezoresistive pressure microsensor with a square-shaped diaphragm for low-pressure biomedical applications is presented. This analysis is developed through a novel model and a finite element method (FEM) model. A microsensor with a d أکثر

The electromechanical analysis of a piezoresistive pressure microsensor with a square-shaped diaphragm for low-pressure biomedical applications is presented. This analysis is developed through a novel model and a finite element method (FEM) model. A microsensor with a diaphragm 1000 &bdquo;m length and with thickness=400 µm is studied. The electric response of this microsensor is obtained with applying voltage into senseor in p-type piezoresistors located on the diaphragm surface. The diaphragm that is 10 &bdquo;m thickexhibits a maximum deflection of 3.74 &bdquo;m using the designed model, which has a relative difference of 5.14 and 0.92% with respect to the comsol model, respectively. The maximum sensitivity and normal stress calculated using the this model are 1.64 mV/V/kPa and 102.1 MPa, respectively. The results of the polynomial model agree well with the Timoshenko model and FEM model for small deflections. In addition, the designed model can be easily used to predict the deflection, normal stress, electric response and sensitivity of a piezoresistive pressure microsensor with a square-shaped diaphragm under small deflections. تفاصيل المقالة

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10 - The Effect of Soccer Ball Impulse on Lower Limbs of the Human Body
Leila Shahryari Behtash JavidSharifi JavidSharifi Mohammad Ali Samianifar

Despite the fact that soccer is one of the most popular sports in the world, little attention has been paid to this game scientifically which could otherwise provide a broad range of interesting outcomes. Sport equipment has a significant effect on how a game is played. أکثر

Despite the fact that soccer is one of the most popular sports in the world, little attention has been paid to this game scientifically which could otherwise provide a broad range of interesting outcomes. Sport equipment has a significant effect on how a game is played. Different features of the soccer ball such as its size, structure, weight and potential incoming pressure also affect the nature and quality of the game. Different models of soccer balls have been developed with the aim of increasing game quality and performance. Many scholars have investigated the displacements during typical soccer games caused by the ball impulse and the feet, but few studies have focused on the interaction between the ball and the feet. The aim of the present study is, thus, to investigate tension development and possible deformations caused by kicking the ball. Players who are well aware of soccer rules and have a little knowledge about soccer-induced injuries easily realize that the impulse of a non-standard ball considering its material, size or weight may severely damage the knees or other body parts. Due to the importance of the issue, to evaluate the impact of the soccer ball on the footballer’s feet, two finite element models of typical soccer balls have been studied with respect to the standard features of the real soccer ball in the three layers of leather, thread and rubber. The first model is proportional to the mass of the standard ball and the second incorporates a mass less than the standard level. Two models of bones are used in the present study: a single layer bone and a two-layer bone with cortical and cancellous tissues. For better understanding of the injuries resulting from the impulse from a non-standard ball, the used finite element software employs mechanic laws of sport biomechanics to provide better understanding of the details using mathematical modeling, computer simulation and experimental measurements. In this regard, this significant point is achieved through modeling the ball impulse to the feet which is quite complex and needs some simplification. As the soccer ball is flexible, most of the force is absorbed by the model’s flexibility. In the other model with a less flexible ball, the force absorbed by the bone is significantly more. تفاصيل المقالة

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11 - Bending Fatigue Tests and Finite Element Models of Steel Rectangular Hollow Sections [SRHS]
islam Ezz El-Arab W Gray

The Welding in cold formed areas is not only an open question for statically loaded sections (brittle fracture) but also for dynamically loaded structures (fatigue resistance). A lot of structures are subjected to dynamic loadings and unfortunately very little informati أکثر

The Welding in cold formed areas is not only an open question for statically loaded sections (brittle fracture) but also for dynamically loaded structures (fatigue resistance). A lot of structures are subjected to dynamic loadings and unfortunately very little information about the influence of welding in the cold formed areas on fatigue resistance is available. In order to establish the fatigue behavior of welded and non-welded rectangular hollow sections specimens, a large number of 4-point bending tests are performed at the Saud Bin Laden Group SBG with cooperation with Buro Happold UK, Laboratory for Steel. Because these tests are very expensive, and because of the large number of parameters regarding the RHS to be investigated (steel grade, wall thickness, load distribution, boundary conditions), a number of finite element models for these specimens are made. By modeling the specimens with different types of finite elements (shells, solids) and taking into account some types of loading distributions and boundary conditions, the obtained results (stresses, strains, displacements) from a static analysis are compared with those obtained from the real 4-points bending tests. In this way, the obtained conclusions would lead to decrease of the number of the specimens that need to be tested as well as the costs of the project. Furthermore, by using finite element analysis, many factors with direct influence on the fatigue resistance can be considered. تفاصيل المقالة

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12 - Analysis of Masonry Infill Panels Retrofitted with FRP Sheets in R/C Frames
Hosein Parastesh Murat Saatcioglu

Masonry infill walls are often used as non-structural elements. According to the past structural failure, ignorance of interaction between infill walls and enclosed frame may lead to the different seismic response for non-ductile building frames. The main contribution o أکثر

Masonry infill walls are often used as non-structural elements. According to the past structural failure, ignorance of interaction between infill walls and enclosed frame may lead to the different seismic response for non-ductile building frames. The main contribution of this paper is to analytically investigate the behavior of reinforced concrete with masonry infill panels as participating structural. In doing so, a finite element model based on an equivalent strut method is conducted to represent the behavior of masonry panels. The strut model is calibrated using the results of the companion experimental program, which examined the cyclic behavior of infill panels with and without FRP sheets. Accordingly, a nonlinear spring element and a shell element are used to simulate the behavior of masonry strut elements and FRP sheets, respectively. The nonlinear static analysis (Push over analysis) is accomplished using SAP2000 [1] structural analysis software for a 10-story building with FRP sheets subjec تفاصيل المقالة

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13 - Effect of flower pattern on the curvature of high-strength steel pipe in roll forming
M. Karimi Firouzjaei H. Moslemi Naeini B. Abbaszadeh M.M. Kasaei

The geometrical characteristic of products is one of the crucial quality indicators in the cold roll forming process. In this process, an appropriate flower pattern for rolls is vital to achieve the desired geometry and quality for high-strength steel pipes. In this pap أکثر

The geometrical characteristic of products is one of the crucial quality indicators in the cold roll forming process. In this process, an appropriate flower pattern for rolls is vital to achieve the desired geometry and quality for high-strength steel pipes. In this paper, four different flower patterns, including circular, edge bending, double radius, and reverse bending are designed for the roll forming process of the high-strength steel pipe. Then, the effect of the flower pattern on the curvature distribution of the deformed strip is investigated using finite element analysis. The accuracy of the finite element model is evaluated by performing experimental tests. The results show that forming the strip with the reverse bending flower pattern leads to a more uniform curvature distribution in its cross-section, especially in the edge portion. Thus, this flower pattern design method is recommended for the roll forming process of the high-strength steel pipes. تفاصيل المقالة

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14 - Finite Element Modeling of Strain Rate and Grain Size Dependency in Nanocrystalline Materials
Minoo Tabanfard

Nanocrystalline materials show a higher strain-rate sensitivity in contrast to the conventional coarse-grained materials and a different grain size dependency. To explain these phenomenon, a finite element model is constructed that considers both grain interior and grai أکثر

Nanocrystalline materials show a higher strain-rate sensitivity in contrast to the conventional coarse-grained materials and a different grain size dependency. To explain these phenomenon, a finite element model is constructed that considers both grain interior and grain boundary deformation of nanocrystalline materials. The model consist of several crystalline cores with different orientations and grain boundary phase. The nonlinear behavior of the nanocrystalline core is implemented by a grain size dependent crystal plasticity. The boundary phase is assumed to have the mechanical properties of quasi-amorphous material. The constitutive equations for both grains interior and boundary phase are implemented into the finite-element software Abaqus. A calibration procedure was used to tune some parameters of the model with the previously published experimental data on the nanocrystalline copper. Then the model is used to predict the material behavior in various strain rates and grain sizes. The stresses obtained from these simulations match well with the experimental data for nanocrystalline copper at different strains and strain rates. Deviation from the Hall-Petch law and inverse Hall-Petch effect are also well illustrated by the model. تفاصيل المقالة

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15 - Numerical Analysis of Severe Plastic Deformation by High Pressure Torsion
mohammadreza kaji Ghader Faraji

High-pressure torsion (HPT) is a metal processing method in which the sample is subjected to a very high plastic shear deformation. This process can produce exceptional levels of grain refinement, and provides a corresponding improvement in mechanical properties. To inv أکثر

High-pressure torsion (HPT) is a metal processing method in which the sample is subjected to a very high plastic shear deformation. This process can produce exceptional levels of grain refinement, and provides a corresponding improvement in mechanical properties. To investigate the stress and strain distribution due to HPT process finite element simulation were conducted to investigate effective parameters. The simulation results demonstrate that the lowest effective strain obtained in the centers of the disk and the highest at the edges. Also, the mean stress varies linearly from the center of the disk to the edge region. The compressive stresses are higher in the disk centers and lower at the edges. By increasing the friction coefficient and the die angle, mean stress decrease and stress variation along the disc diameters become more homogeneous. Increasing of the pressure load leads to increase the mean stress and its heterogeneity along the disc radius. تفاصيل المقالة

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16 - Deformation of Al Alloy during Integrated Extrusion and ECAP: A Simulation Research
Ankit Sahai Shanti S. Sharma Suren N. Dwivedi

Bulk nanomaterial have several applications in automobile, aerospace, medical and manufacturing applications. These are produced by subjecting materials to severe plastic deformation (SPD) and have widely emerged as a technique for grain refinement in Al, Cu, Ti, Mg all أکثر

Bulk nanomaterial have several applications in automobile, aerospace, medical and manufacturing applications. These are produced by subjecting materials to severe plastic deformation (SPD) and have widely emerged as a technique for grain refinement in Al, Cu, Ti, Mg alloys with improved mechanical properties. Equal Channel Angular Pressing (ECAP) is one such SPD technique employed to produce bulk ultra-fine grained (UFG) materials by introducing a large amount of shear strain into the materials without changing the billet shape or dimensions. FE (Finite Element) modeling of SPD processes has become an important tool for designing feasible production processes, because of its unique capability to describe the complex geometry and boundary conditions. In this proposed work, integrated SPD processes namely Extrusion + ECAP (Ex-ECAP) is proposed and the specimen is subjected to these processes in the same die set-up. The 3D finite element modeling of Al6061 was performed using metal forming software FORGE. The dies used in both the processes during the simulation of Al6061 billet include a channel angle of 900 and outer corner angle fixed at 160 with simulation performed for different plunger velocities. The simulation results depict the change in equivalent strain in the entire specimen on account of these processes. The evolution of strain at different considered cross-sections is analyzed. Also, the variation in extrusion force and energy are studied for the considered process parameters. The FE simulations greatly help in designing the dies for various experimental conditions to produce bulk nanomaterial. تفاصيل المقالة

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17 - پیش‌بینی پارامترهای چسبندگی الیاف فولادی هوک شکل و بتن با استفاده از شبکه‌های عصبی مصنوعی
امیر ابراهیم اکبری بقال امیر ابراهیم اکبری بقال

با توجه به اهمیت بکارگیری الیاف فولادی در تقویت بتن، در تحقیق حاضر با استفاده از شبکه‌های عصبی مصنوعی به پیش‌بینی رفتار بیرون کشیدگی الیاف فولادی هوک شکل از بتن پرداخته شده است. به دلیل محدودیت داده‌های جامع آزمایشگاهی، از داده‌های به دست آمده از تحلیل المان محدود به عن أکثر

با توجه به اهمیت بکارگیری الیاف فولادی در تقویت بتن، در تحقیق حاضر با استفاده از شبکه‌های عصبی مصنوعی به پیش‌بینی رفتار بیرون کشیدگی الیاف فولادی هوک شکل از بتن پرداخته شده است. به دلیل محدودیت داده‌های جامع آزمایشگاهی، از داده‌های به دست آمده از تحلیل المان محدود به عنوان ورودی شبکه عصبی استفاده شده است. به منظور شبیه‌سازی‌ بیرون کشیدگی الیاف از روش المان محدود سه‌بعدی و نرم‌افزار آباکوس استفاده می‌شود. در مدل المان محدود، اندرکنش بین الیاف و بتن با استفاده از مفهوم ناحیه انتقالی سطح مشترک شبیه‌سازی شده است که پارامترهای آن با استفاده از روش المان محدود معکوس و استفاده از نتایج تست تجربی بیرون‌کشیدگی انجام پذیرفته بر روی یک نمونه الیاف به دست آمده است. پس از صحت‌سنجی نتایج مدل عددی با نتایج تجربی، نتایج به ازای پارامترهای مؤثر الیاف استخراج شده و بر اساس آنها مدل‌سازی با استفاده از شبکه‌های عصبی صورت گرفته است. پیش‌بینی نیروی بیرون‌کشیدگی توسط شبکه‌های عصبی مصنوعی چندلایه و الگوریتم آموزش انتشار به عقب، با تکنیک بهینه‌سازی مارکورادت-لونبرگ انجام شده است. نتایج نشان می‌دهد که مدل شبکه عصبی ارائه شده در این تحقیق، به دلیل توانای استفاده از متغیرهای بیشتر در مدل‌سازی و نتایج دقیق‌تر، روشی مؤثر برای پیش‌بینی نیروی بیرون‌کشیدگی الیاف از بتن است. تفاصيل المقالة

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18 - بررسی مقاومت خمشی بتن فوق‌توانمند تقویت شده با الیاف فولادی با استفاده از مدل المان محدود چندمقیاسه
امیر ابراهیم اکبری بقال احمد ملکی رامین وفائی پور

10.30495/civil.2021.684368

هدف اصلی تحقیق حاضر، توسعه مدل المان محدود به منظور مطالعه تأثیر الیاف فولادی شکل بر مقاومت خمشی بتن فوق توانمند الیافی است. بدین منظور، به منظور شبیه‌سازی عددی، مدل المان محدود چندمقیاسه توسعه داده شد که در آن بتن به صورت ماده همگن و یکنواخت مدل‌سازی شده و الیاف فولادی أکثر

هدف اصلی تحقیق حاضر، توسعه مدل المان محدود به منظور مطالعه تأثیر الیاف فولادی شکل بر مقاومت خمشی بتن فوق توانمند الیافی است. بدین منظور، به منظور شبیه‌سازی عددی، مدل المان محدود چندمقیاسه توسعه داده شد که در آن بتن به صورت ماده همگن و یکنواخت مدل‌سازی شده و الیاف فولادی به صورت تصادفی در داخل آن توزیع شده است. به منظور در نظر گرفتن فرضیات واقع‌بینانه‌تر، ناحیه چسبندگی بین الیاف و بتن نیز لحاظ شده است. پس از صحت‌سنجی نتایج مدل المان محدود با نتایج تست‌های تجربی، تأثیر پارامترهای مانند کسر حجمی و چسبندگی الیاف فولادی بر استحکام مشخصه‌های مقاومت خمشی بتن‌های فوق توانمند تقویت شده با الیاف مورد مطالعه عددی قرار گرفته است. نتایج نشان می‌دهد که تأثیر استفاده از الیاف بر میزان جذب انرژی توسط بتن فوق توانمند الیافی بسیار بیشتر از تأثیر آن بر سایر مشخصه‌های این نوع بتن‌ها می‌باشد و مخصوصاً استفاده از الیاف در حجم‌های پایین الیاف، تأثیری بسیار قابل ملاحظه بر قابلیت جذب انرژی دارد به طوری که به ازای 5/0 درصد کسر حجمی الیاف فولادی در حدود 17 برابر نسبت به نمونه بتن فوق توانمند بدون الیاف افزایش می‌یابد. تفاصيل المقالة

حرية الوصول المقاله

19 - ارزیابی عملکرد لرزه‌ای سازه‌های فولادی مجهز به مهاربندهای ترکیبی فولاد-آلیاژ حافظه‌دار شکلی
محمد هوشمند بهزاد رافضی جلیل خلیل علافی

در این مقاله به بررسی رفتار لرزه‌ای مهاربندهای ترکیبی از جنس فولاد و آلیاژهای حافظه‌دار شکلی پرداخته شده است. جهت بررسی از شش مدل مهاربند ترکیبی با میزان مصرف آلیاژ حافظه‌دار شکلی با معیار طول به ترتیب صفر ، 20 ، 40 ، 60 ، 80 و 100 درصد از طول کل استفاده شده است. ارزیاب أکثر

در این مقاله به بررسی رفتار لرزه‌ای مهاربندهای ترکیبی از جنس فولاد و آلیاژهای حافظه‌دار شکلی پرداخته شده است. جهت بررسی از شش مدل مهاربند ترکیبی با میزان مصرف آلیاژ حافظه‌دار شکلی با معیار طول به ترتیب صفر ، 20 ، 40 ، 60 ، 80 و 100 درصد از طول کل استفاده شده است. ارزیابی مدل‌ها به کمک تحلیل دینامیکی غیر خطی تحت زلزله السنترو مقیاس شده با شتاب‌های حداکثر 0.6g و 0.9g در نرم افزار ANSYS v11 انجام گرفته است. نتایج مطالعات انجام شده مقادیر طولی بهینه برای درصد مهاربند ترکیبی را مشخص می‌کند بطوریکه می‌توان با استفاده از مقادیر پیشنهادی و طرح ارائه شده، سازه‌هایی بار رفتار لرزه‌ای مناسب و با هزینه ساخت قابل توجیه طراحی و اجرا نمود. تفاصيل المقالة

حرية الوصول المقاله

20 - Finite Element Model Updating of a Frame with Direct and Sensitivity-Base Methods
مهدی تاجداری کاوه عباسی

This paper presents an overview of model updating and particularly its application for updating of frame model. In this article a mathematical model of the frame was produced with finite element method. The frame was subjected to hammer modal testing. Then the results o أکثر

This paper presents an overview of model updating and particularly its application for updating of frame model. In this article a mathematical model of the frame was produced with finite element method. The frame was subjected to hammer modal testing. Then the results of the modal testing were compared with those predicted with the model. This comparison revealed discrepancies between these two sets of results. It is a commonly known fact that incorrect values of parameters in a model, among other things, do cause these discrepancies. In order to improve the correlation between the measured and the predicted results and hence improve the reliability of the model, the model was subjected to finite element model updating. In this updating process, incorrect values of parameters in a model are adjusted. Also it is important in updating that the FE model be simple and in the same time can give good results.The objective of this article is to use direct and sensitivity-base methods for frame and also compare these methods. تفاصيل المقالة

حرية الوصول المقاله

21 - A Roll Wear Prediction Model in Hot Plate Rolling
امیر نورانی محمود سلیمی

In this paper, the wear of work roll in hot plate rolling is introduced and the parameters affecting wear mechanisms in hot strip mill are investigated. In addition, different wear mechanisms in hot rolling and the differences between these mechanisms in different stand أکثر

In this paper, the wear of work roll in hot plate rolling is introduced and the parameters affecting wear mechanisms in hot strip mill are investigated. In addition, different wear mechanisms in hot rolling and the differences between these mechanisms in different stands are explained. Using the finite element method and the rolling equations, a work roll wear model is proposed. Wear is modeled using the resultant pressure distribution along the roll barrel. To obtain the tentative coefficient, summation of wear in each pass schedule is obtained and calibrated via actual wear of samples tested in the Mobarakeh Steel Company. Finally, the theoretical wear values are compared with those of the experiment. The predicted wear profiles are found to be in good agreement with those of the experimental measured values. تفاصيل المقالة

حرية الوصول المقاله

22 - پیش‌بینی پارامترهای چسبندگی الیاف فولادی هوک شکل و بتن با استفاده از شبکه‌های عصبی مصنوعی
امیر ابراهیم اکبری بقال

با توجه به اهمیت بکارگیری الیاف فولادی در تقویت بتن، در تحقیق حاضر با استفاده از شبکه‌های عصبی مصنوعی به پیش‌بینی رفتار بیرون کشیدگی الیاف فولادی هوک شکل از بتن پرداخته شده است. به دلیل محدودیت داده‌های جامع آزمایشگاهی، از داده‌های به دست آمده از تحلیل المان محدود به عن أکثر

با توجه به اهمیت بکارگیری الیاف فولادی در تقویت بتن، در تحقیق حاضر با استفاده از شبکه‌های عصبی مصنوعی به پیش‌بینی رفتار بیرون کشیدگی الیاف فولادی هوک شکل از بتن پرداخته شده است. به دلیل محدودیت داده‌های جامع آزمایشگاهی، از داده‌های به دست آمده از تحلیل المان محدود به عنوان ورودی شبکه عصبی استفاده شده است. به منظور شبیه‌سازی‌ بیرون کشیدگی الیاف از روش المان محدود سه‌بعدی و نرم‌افزار آباکوس استفاده می‌شود. در مدل المان محدود، اندرکنش بین الیاف و بتن با استفاده از مفهوم ناحیه انتقالی سطح مشترک شبیه‌سازی شده است که پارامترهای آن با استفاده از روش المان محدود معکوس و استفاده از نتایج تست تجربی بیرون‌کشیدگی انجام پذیرفته بر روی یک نمونه الیاف به دست آمده است. پس از صحت‌سنجی نتایج مدل عددی با نتایج تجربی، نتایج به ازای پارامترهای مؤثر الیاف استخراج شده و بر اساس آنها مدل‌سازی با استفاده از شبکه‌های عصبی صورت گرفته است. پیش‌بینی نیروی بیرون‌کشیدگی توسط شبکه‌های عصبی مصنوعی چندلایه و الگوریتم آموزش انتشار به عقب، با تکنیک بهینه‌سازی مارکورادت-لونبرگ انجام شده است. نتایج نشان می‌دهد که مدل شبکه عصبی ارائه شده در این تحقیق، به دلیل توانایی استفاده از متغیرهای بیشتر در مدل‌سازی و نتایج دقیق‌تر، روشی مؤثر برای پیش‌بینی نیروی بیرون‌کشیدگی الیاف از بتن است. تفاصيل المقالة

فهرس المقالات Finite element model

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