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دسترسی آزاد مقاله
1 - Investigation on Failure Loads and Failure Modes for Two Parallel Pin-Loaded Holes Made from Unidirectional Glass-Epoxy Nanoclay Laminates
sajjad dehghanpour keivan hosseini safari Farzan Barati Mohammadmahdi AttarPurpose of this study is to obtain failure modes and failure loads of two Parallel pin loaded holes in unidirectional glass fibre/epoxy by adding nanoclay in the absence of nanoclay composite laminates using finite element analysis; the results are validated through exp چکیده کاملPurpose of this study is to obtain failure modes and failure loads of two Parallel pin loaded holes in unidirectional glass fibre/epoxy by adding nanoclay in the absence of nanoclay composite laminates using finite element analysis; the results are validated through experiment. The geometrical parameters studies in this survey include the distance between the diameter of the hole (e/d) and the free edge of specimen, the distance between two holes-to-hole diameter (M/d). The samples were exposed to constant speed tensile loading. The results showed that by adding nanoclay, failure load increases and failure modes varies from shear out to bearing failure. Furthermore, increasing distance from the free edge of the pin centre’s increases load bearing capacity of two type of composite materials and changes the failure mode from shear to the bear, it increases and decreases the distance from canter’s of pin in layers with and without nanoclay particles, respectively and changes failure mode from shear to bear mode. In order to find morphology of specimens and dispersion quality, Scanning Electron Microscope (SEM) was used. For predicting failure load and differentiating failure modes, Tsai-hill failure criteria associated with material property degradation is used. Experimental and FEM results indicate importance of considering the impact of e/d and M/d ratios in the design of two Parallel pin joints. ANSYS was used to carry out numerical simulation and the results denote a good agreement between numerical and experimental results. In this study, by designing an experimental and numerical procedure to estimate the effect of nanoclay, on failure mode and failure load of typical composite material, glass-epoxy, we could illustrate that adding nanoclay brought with it improvement of shear and tensional strength of glass-epoxy about 10 %. پرونده مقاله -
دسترسی آزاد مقاله
2 - Temperature Effect on Mechanical Properties of Top Neck Mollusk Shells Nano-Composite by Molecular Dynamics Simulations and Nano-Indentation Experiments
A Nouroozi Masir A Darvizeh A ZajkaniDiscovering the mechanical properties of biological composite structures at the Nano-scale is much interesting today. Top Neck mollusk shells are amongst biomaterials Nano-Composite that their layered structures are composed of organic and inorganic materials. Since the چکیده کاملDiscovering the mechanical properties of biological composite structures at the Nano-scale is much interesting today. Top Neck mollusk shells are amongst biomaterials Nano-Composite that their layered structures are composed of organic and inorganic materials. Since the Nano indentation process is known as an efficient method to determine mechanical properties like elastic modulus and hardness in small-scale, so, due to some limitation of considering all peripheral parameters; particular simulations of temperature effect on the atomic scale are considerable. The present paper provides a molecular dynamics approach for modeling the Nano-Indentation mechanism with three types of pyramids, cubic and spherical indenters at different temperatures of 173, 273, 300 and 373K. Based on load-indentation depth diagrams and Oliver-Far equations, the findings of the study indicate that results in the weakening bond among the bilateral atoms lead to reduced corresponding harnesses. Whenever, the temperature increases the elastic modulus decrease as well as the related hardness. Moreover, within determining the elastic modulus and hardness, the results obtained from the spherical indenter will have the better consistency with experimental data. This study can be regarded as a novel benchmark study for further researches which tend to consider structural responses of the various Bio-inspired Nano-Composites. پرونده مقاله -
دسترسی آزاد مقاله
3 - Effect of Follower Force on Vibration Frequency of Magneto-Strictive-Faced Sandwich Plate with CNTR Composite Core
M.R Ghorbanpour Arani Z Khoddami MaraghiThis study deals with the vibration response of sandwich plate with nano-composite core and smart magneto-strictive face sheets. Composite core is reinforced by carbon nanotubes (CNTs) and its effective elastic properties are obtained by the rule of Mixture. Terfenol-D چکیده کاملThis study deals with the vibration response of sandwich plate with nano-composite core and smart magneto-strictive face sheets. Composite core is reinforced by carbon nanotubes (CNTs) and its effective elastic properties are obtained by the rule of Mixture. Terfenol-D films are used as the face sheets of sandwich due to magneto-mechanical coupling in magneto-strictive material (MsM). In order to investigate the magnetization effect on the vibration characteristics of sandwich plate, a feedback control system is utilized. Also the sandwich plate undergoes the follower forces in opposite direction of x. Based on energy method, equations of motions are derived using Reddy’s third order shear deformation theory, and Hamilton’s principle and solved by differential quadrature method (DQM). A detailed numerical study is carried out based on third-order shear deformation theory to indicate the significant effect of follower forces, volume fraction of CNTs, temperature change, core-to-face sheet thickness ratio and controller effect of velocity feedback gain on dimensionless frequency of sandwich plate. These finding can be used to automotive industry, aerospace and building industries. پرونده مقاله -
دسترسی آزاد مقاله
4 - Optimizing Surface Roughness of Nylon6/CaCO3 Nano-Composites Using Harmony Search Algorithm
Shahab Mohammadi Reza Farshbaf Zinati MohammadReza RazfarNowadays, polymer-based Nano-composites are of special importance in industry considering their mechanical properties including high strength to weight ratio. On another hand, since Nano-composites produced by methods such as extrusion are at simple cross sections, it i چکیده کاملNowadays, polymer-based Nano-composites are of special importance in industry considering their mechanical properties including high strength to weight ratio. On another hand, since Nano-composites produced by methods such as extrusion are at simple cross sections, it is necessary to machine them in order to reach geometrically complex figures. Surface roughness is a parameter affecting mechanical specifications of the machined part. Thus, it is necessary to study surface roughness of the machined parts to reach optimized cutting parameters and optimized surface roughness. The present paper tries to experimentally test milling of Nylon 6/ CaCo3 Nano-composites and measure surface roughness of the milled surfaces using the obtained data. The obtained data were used to model surface roughness to obtain an appropriate model for its milling. Finally, the obtained model was optimized using harmony search algorithm to reach optimized surface roughness and cutting parameters. پرونده مقاله -
دسترسی آزاد مقاله
5 - An investigation on Al6061/TiB2 nano composites production through Mechanical Alloying route and their corrosion behavior
Iman ebrahimzadeh Farhad Gharavi G.H. BorhainAluminum-based alloy composites with high strength and low density can be used in corrosive environments. In this research, the nano-powders of A16061 alloy and A16061/TiB2 composite were synthesized by mechanical alloying (MA) method. Then, A16061 /TiB2 nano-composite چکیده کاملAluminum-based alloy composites with high strength and low density can be used in corrosive environments. In this research, the nano-powders of A16061 alloy and A16061/TiB2 composite were synthesized by mechanical alloying (MA) method. Then, A16061 /TiB2 nano-composite bulk samples were prepared at laboratory scale by hot extrusion approach. Transmission electron microscopy (TEM) and X-ray diffraction (XRD) devices were respectively used for measurement of particles and grains, and the polarization test was employed to assess the corrosion behavior of A16061 /TiB2 nano-composites. The grains size of hot extrusion samples were calculated as about 95 nm. Uniform corrosion behavior and pitting of the produced nano samples of MA6061 /1.25 TiB2 have higher corrosion resistance compared to the alloy samples of MA6061.3. The uniform corrosion in the 2MA-Al-6061/1.25TiB2 composite had the lowest rate compared to other samples.The sensitivity of this alloy to pitting corrosion has raised compared to the melting state; however, this sensitivity is less than the alloy made by mechanical alloying method. پرونده مقاله -
دسترسی آزاد مقاله
6 - Nonlinear bucking analysis of Polystyrene, Polyvinyl chloride, and Polypropylene cylindrical nano-composite shells reinforced by carbon nanotubes based on micro-mechanics and finite element methods
Reza Hosseini-Ara Mohsen AkbariIn this paper, we present nonlinear buckling instability analysis of Polystyrene, Polyvinyl chloride, and Polypropylene nano-composite shell-structures reinforced by carbon nanotubes (CNTs) under uni-axial compressive load to obtain a more conservative buckling response چکیده کاملIn this paper, we present nonlinear buckling instability analysis of Polystyrene, Polyvinyl chloride, and Polypropylene nano-composite shell-structures reinforced by carbon nanotubes (CNTs) under uni-axial compressive load to obtain a more conservative buckling response as compared with linear analysis. For this end, the Mori-Tanaka method is firstly utilized to estimate the effective elastic modulus of composites having aligned oriented straight CNTs. Then, a novel model based on micro-mechanics and finite element method is developed for buckling analysis of a cylindrical nano-composite shell reinforced by CNTs and various effects of different types of polymer matrices (Polystyrene, Polyvinyl chloride, and Polypropylene), CNTs volume fraction, CNTs orientation angle, aspect ratio of cylinder, and different boundary conditions (simply supported and clamped ends) on critical buckling load of cylindrical nano-composite shells are discussed. The proposed model is based on Mori-Tanaka micro-mechanics which is developed in ABAQUS finite element package. Herein, numerical results show different behavior from shell-type buckling to beam-type buckling in L/R =8 due to change of the cylinder’s aspect ratios. Moreover, the developed finite element code and numerical results are compared and validated with Mori-Tanaka analytical model in available literature and shown a good agreement. پرونده مقاله -
دسترسی آزاد مقاله
7 - تولید پوشش نانوکامپوزیتی Ni-Co/SiO2 به روش رسوب الکتروشیمیایی جریان مستقیم
سیاوش ایمانیان علی شکوه فر حامد بخشیپوشش نانوکامپوزیتی Ni-Co/SiO2 با روش اکتروشیمیایی جریان مستقیم تولید شد. آنالیز پراش اشعه ی ایکس (XRD) و تصاویر میکروسکوپ الکترونی روبشی گسیل میدانی (FE-SEM) از یک پوشش آلیاژی نیکل-کبالت و پوشش نانوکامپوزیتی Ni-Co/SiO2 که همگی شرایط الکتروشیمیایی تولیدشان یکسان بود، تهی چکیده کاملپوشش نانوکامپوزیتی Ni-Co/SiO2 با روش اکتروشیمیایی جریان مستقیم تولید شد. آنالیز پراش اشعه ی ایکس (XRD) و تصاویر میکروسکوپ الکترونی روبشی گسیل میدانی (FE-SEM) از یک پوشش آلیاژی نیکل-کبالت و پوشش نانوکامپوزیتی Ni-Co/SiO2 که همگی شرایط الکتروشیمیایی تولیدشان یکسان بود، تهیه شد و اندازه ی دانه و مورفولوژی سطح آن ها مورد مقایسه قرار گرفت و تحلیل شد. اندازه ی دانه ی پوشش نانوکامپوزیتی کمتر از پوشش آلیاژی بود و مورفولوژی سطح مربوط به پوشش نانوکامپوزیتی نسبت به پوشش آلیاژی، کروی ریزتر و صاف تر بود. سختی پوشش نانوکامپوزیتی بیشتر از پوشش آلیاژی بود. اگر دمای الکترولیت 50 درجه ی سیلیسیوس باشد، انگاه پوشش نانو کامپوزیتی Ni-Co/SiO2 ماکزیمم مقدار سختی را دارد. افزودن سورفکتانت به الکترولیت مانع از اگلومره شدن نانوذرات و در نتیجه افزایش مقدار نانوذرات در پوشش و درنتیجه افزایش میکروسختی پوشش نانو کامپوزیتی Ni-Co/SiO2 شد. در مورد پوشش تولید شده در اینجا، تاثیر SDS بیشتر از CTAB بود و مقدار بهینه ی غلظت برای SDS در الکترولیت0.3 گرم بر لیتر بود. پرونده مقاله -
دسترسی آزاد مقاله
8 - ارزیابی سایشی لایه سطحی نانوکامپوزیت هیبریدیAl7075/SiC-BN تشکیل شده توسط روش همزن اصطکاکی
محمود سلیمانی سیدفرشید کاشانی بزرگ علی محمد هادیاندر این پژوهش، از روش همزن اصطکاکی جهت تشکیل یک لایه سطحی کامپوزیت هیبریدی دارای ذرات SiC و BN بر روی آلیاژآلومینیوم T6-7075 در راستای بهبود سختی و مقاومت به سایش استفاده شده است. مخلوط ذره ای افزودنی های SiC وBN به نسبت وزنی برابر به ترتیب در مقیاس نانو و میکرومتری در د چکیده کاملدر این پژوهش، از روش همزن اصطکاکی جهت تشکیل یک لایه سطحی کامپوزیت هیبریدی دارای ذرات SiC و BN بر روی آلیاژآلومینیوم T6-7075 در راستای بهبود سختی و مقاومت به سایش استفاده شده است. مخلوط ذره ای افزودنی های SiC وBN به نسبت وزنی برابر به ترتیب در مقیاس نانو و میکرومتری در داخل شکافی در مقابل حرکت ابزار قرار داده شدند. جهت پخش ذرات افزودنی و تامین یکنواختی تا پنج پاس دیگر نیز اعمال شد. بررسی های میکروسکوپی نشان داد که ذرات بعد از شش پاس به صورت تقریبا یکنواخت توزیع شده است. در اثر روند ترمومکانیکی فرایند همزن اصطکاکی، میزان سختی زمینه Al7075 به طور چشم گیر کاهش یافته که مرتبط با حل شدن رسوبات آن است. با افزودن مخلوط پودری و تشکیل لایه نانوکامپوزیت هیبریدی Al7075/SiC-BNسختی و مقاومت به سایش نسبت به آلیاژ پایه ارتقا نیافت و این در حالی بود که دانههای زمینه آلومینیومی از 9 به کمتر از1 میکرون در اثر فرایند همزن اصطکاکی کاهش یافته بود. لیکن با انجام عملیات حرارتی T6 بر لایه نانوکامپوزیت هیبریدی، میزان سختی و مقاومت به سایش هر کدام تا حدود یک سوم مقادیرآلیاژ پایه افزون برمقادیر آلیاژ پایه گردید. این موارد مرتبط با تشکیل رسوبات بر مبنای ترکیبات بین فلزی در اثر عملیات حرارتی T6 بود. پرونده مقاله -
دسترسی آزاد مقاله
9 - Investigation and optimization of the effect of input parameters on output parameters of electrical discharge machining of A356 nano-composite reinforced by SiC
Amir Rahmani Ali Mokhtarian Mojtaba RahimiIn this study, the impact of input parameters of Electrical Discharge Machining (EDM) on A356 nano-composite reinforced by 6% SiC was investigated and optimized using Taguchi's method based on the L9 orthogonal array and duplicated levels method. We considered voltage, چکیده کاملIn this study, the impact of input parameters of Electrical Discharge Machining (EDM) on A356 nano-composite reinforced by 6% SiC was investigated and optimized using Taguchi's method based on the L9 orthogonal array and duplicated levels method. We considered voltage, current intensity, pulse on-time, and pulse off-time as the input parameters. Furthermore, material removal rate (MRR), tool wear rate (TWR), and surface roughness (SR) were taken into account as the output parameters. The analysis of results and examination of the signal-to-noise graphs (S/N) and analysis of variance (ANOVA) were performed using Minitab@16 software. Moreover, with the determination of the loss function of total normalized values of the output parameters based on assumed weight functions, the optimal level of each input parameter was established. Besides, the magnitude of contribution percentage of each of the input parameters in the total variance was computed through the variance analysis. According to the achieved results, the second level of the voltage (250 V), the first level of the current intensity (10 A), the third level of the pulse on-time (100 µs), and the first level of the pulse off-time (30 µs) were determined as the optimal input parameters. The contribution percentage of the input parameters for voltage, current intensity, pulse on-time, and pulse off-time was determined respectively to be 20.7, 62.06, 9.19, and 8.05. پرونده مقاله
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