جستجوی مقالات مرتبط با کلیدواژه « Finite element method (FEM) » در نشریات گروه « مواد و متالورژی »
تکرار جستجوی کلیدواژه «Finite element method (FEM)» در نشریات گروه «فنی و مهندسی»-
Finite element analysis has been carried out to investigate the effect of various parameters on axisymmetric hot extrusion process using aluminum alloy. The objective of the present work is to investigate the effect of friction coefficient, die angle, die-profile radius and predefined temperature of workpiece through FEM simulation of extrusion process. Nodal temperature distribution, heat flux, peak temperature at nodes and peak flux induced are identified as the output variables to assess the thermo-mechanical deformation behavior of aluminum alloy. Mesh sensitivity analysis is performed for the evaluation of mesh convergence as well as depicts the accuracy of present FEM model. Higher will be the coefficient of friction between interacting surfaces of die-billet assembly, more will be the increment in nodal temperature in billet. Higher will be the coefficient of friction, higher will be the generation of heat flux within billet, as this is achieved for highest coefficient of friction. Peak nodal temperature diminishes with increase in die profile radius nearly by 17 %.Maximum heat flux diminishes non-linearly by 30% with increase in die profile radius. Maximum nodal temperature increases nearly linearly by 14% with increment in predefined temperature of billet. Maximum heat flux decreases non-linearly by 5 % with increment in the initial temperature of workpiece. Validation of present numerical model is established on the basis of deformation behavior in terms of evolution of nodal temperature distribution upon comparison with previous studies available in literature.
Keywords: extrusion, coefficient of friction, die-angle, temperature, flux, Finite element method (FEM)} -
One of the interesting state-of-the-art approaches to welding is the process of friction stir welding (FSW). In comparison with the fusion processes, FSW is an advantageous method as it is suitable for the non-fusion weldable alloys and polymeric materials joining. Regarding the materials pure solid state joining, it also provides joints with less distortion and enhanced mechanical properties. In the present work, a three-dimensional (3D) model based on finite element analysis was applied to study the thermal history and thermomechanical procedure in friction stir welding of high density polyethylene plate. The technique includes the tool mechanical reaction and the weld material thermomechanical procedure. The considered heat source in the model, includes the friction among three items: the material, the probe and the shoulder. Finally, the model was validated by measuring actual temperatures near the weld nugget using thermocouples, and good agreement was obtained for studied materials and conditions.Keywords: Polyethylene (PE), Friction stir welding (FSW), Finite element method (FEM), Temperature distribution, Thermomechanical model}
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در این پژوهش، تاثیر اندازه و موقعیت تورق بر پارامترهای ارتعاشی تیر کامپوزیتی متعامد متقارن چندلایه به روش های تحلیلی، اجزای محدود و تجربی ارایه شده است. در روش تحلیلی، تیر متورق به چهار زیرتیر تقسیم شده و دو مدل مود آزاد و مقید برای مدل سازی تداخل دو زیرتیر در محل تورق در نظر گرفته شده است. همچنین اثرات وابستگی کشش-خمش به دلیل تقسیم تیر به زیرتیرهای نامتقارن لحاظ شده است. در روش اجزای محدود، تیر کامپوزیتی با اندازه و موقعیت های مختلف تورق در نرم افزار اجزای محدود آباکوس شبیه سازی و فرکانس های طبیعی و شکل مودها از تحلیل مودال به دست آمده است. دو مدل مود آزاد و مقید با درنظرگرفتن شرایط مرزی، قیود، غیرخطی ها، شرایط تماسی و المان های مناسب شبیه سازی شده است. نتایج عددی دو مدل مود آزاد و مقید از هر دو روش تئوری برای تیر کامپوزیتی متعامد متقارن دارای تورق با اندازه و موقعیت های مختلف ارایه و مقایسه می شود. همچنین به منظور بررسی تاثیرات موقعیت طولی تورق های نسبتا کوچک بر سه فرکانس اول، پس از ساخت نمونه های کامپوزیت، آزمون های تجربی آنالیز مودال انجام و برای شرایط مرزی مختلف، فرکانس های طبیعی استخراج می شود. نتایج حاصل نشان می دهد که فرکانس های تحلیلی، اجزای محدود و تجربی تطابق خوبی با یکدیگر دارند.کلید واژگان: تیر کامپوزیتی چندلایه, تورق, تحلیل ارتعاشات, روش اجزای محدود, آنالیز مودال}In this study, the effects of delamination size and location on vibration characteristics of laminated composite beams are investigated via analytical, finite element and experimental methods. In the analytical method, the delaminated beam is divided into four interconnected beams and the interaction of two sub-beams at the location of delamination is simulated by both constrained and free mode models. The effect of bending-extension coupling is taken into account in the analytical formulation. In finite element method, modal analysis is performed on the delaminated composite beams with different delamination sizes and locations and various boundary conditions using commercial finite element software, ABAQUS. Both free and constrained mode models are simulated in the finite element model using suitable interactions, nonlinearities and friction conditions. Analytical and finite element results of both constrained and free mode models are compared for a symmetric cross-ply delaminated composite beam with various sizes and locations of delamination. Also, in order to investigate the effects of axial location of relatively small delamination on the first three natural frequencies, modal tests are done on glass/epoxy composites for various boundary conditions. Results show that analytical, finite element and experimental frequencies have good agreement with each other.Keywords: Laminated Composite Beam, Delamination, Vibration Analysis, Finite Element Method (FEM), Modal Analysis}
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Fixture design is crucial part of manufacturing process. Fixture design is a critical design activity process, in which automation plays an integral role in linking computer-aided design (CAD) and computer-aided manufacturing (CAD). This paper presents a literature review in computer aided fixture design (CAFD) in terms of automation and optimization techniques over the past decades. First, the reason behind necessity of automated fixture design is stated. According to the degree of automation, fixture design methods are then categorized based on significant work done in the CAFD field. Regarding the need of automated fixture design systems, optimization techniques, which are mostly used for automated CAFD methods, are closely considered. The significant optimization techniques works are then studied in case of applications and working principle. At the end, the current weaknesses of the existing methods and the research fields, which require deeper studies as future trends, are presented as well.Keywords: Computer aided fixture design (CAFD), Genetic algorithm (GA), Finite element method (FEM), Fixture design automation}
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Using the Frobenius series method (FSM), an analytical solution is developed to obtain mechanical stresses of thick spherical pressure vessels made of functionally graded materials (FGMs). The cylinder pressure vessel is subjected to uniform internal pressure. The modulus of elasticity is graded along the radial direction according to power functions of the radial direction. It is assumed that Poisson’s ratio is constant across the cylinder thickness. Primarily, displacements and stresses is obtained as closed-form solutions. Next, the profiles are plotted for different values of inhomogeneity constant along the radial direction. Finally, the problem was solved, using the finite element method (FEM). The obtained results of finite element method were compared with those of the analytical method. The analytical solutions and the solutions carried out through the FEM show good agreement. The values used in this study are arbitrary chosen to demonstrate the effect of inhomogeneity on displacements, and stresses distributions.Keywords: Thick sphere, Pressure vessel, Exponential, Frobenius series method (FSM), Finite element method (FEM)}
نکته
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