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دسترسی آزاد مقاله
1 - Numerical and Experimental Static Bending Analysis of Composite Sandwich Panels with Grid-Stiffened Cores Before and After Transverse Impact Loading
Ali Asghar Davoodabadi Ali Davar Mohsen Heydari Beni Jafar Eskandari JamNowadays grid structures are considered as one of the most useful composites because of their various applications. Since grid structures are vulnerable to impact loads, they should be investigated under such loadings. The present paper studies the low-velocity impact l چکیده کاملNowadays grid structures are considered as one of the most useful composites because of their various applications. Since grid structures are vulnerable to impact loads, they should be investigated under such loadings. The present paper studies the low-velocity impact loading of sandwich panels with grid-stiffened cores using both experimental and numerical simulations. In addition to the impact behaviour and the resultant damage of the sandwich panels, the behaviour of these structures under three-point bending was studied before and after the impact loading. The results were provided for impact and bending loadings separately. Then the effect of impact loadings on bending strength was investigated and it was found that the impact loading decreases the bending strength. A consistency between numerical and experimental results was also observed, which confirms the applicability of the Finite Element Method (FEM) in simulating the behaviour of such structures under impact and bending loads, while saving lots of time, efforts and costs. پرونده مقاله -
دسترسی آزاد مقاله
2 - Investigation of Oblique Blast Loading on Trapezoidal Corrugated Core Sandwich Panels; Experimental and Numerical Study
H Mohammadi Hooyeh A Naddaf Oskouei T Mirzababaie Mostofi Kh VahediIn this work dynamic response of trapezoidal corrugated core sandwich panels subjected to oblique blast loading are studied both numerically and experimentally. The stand-off distance which has been determined from sandwich panel to center of the nearest face of the exp چکیده کاملIn this work dynamic response of trapezoidal corrugated core sandwich panels subjected to oblique blast loading are studied both numerically and experimentally. The stand-off distance which has been determined from sandwich panel to center of the nearest face of the explosive cylinder is considered 300 mm. the experiments was performed at Four blast tube with different included angles of 0°, 15°, 30° and 45° respect to sandwich target plate. The results of numerical simulation, obtained using coupled Eulerian – Lagrangian (CEL) method at ABAQUS/Explicit software. Maximum mid- point deflection of back and front faces are compared with experiment results. The results show that with increasing angle of tilt of explosive the amount of back face deflection at angles of tilt 15°, 30° and 45° respect to the case of 0°, 4.68%, 5.86% and 9.77% decreases respectively. It is found that at the z direction, deformation profile is completely dome-shaped while the profile in the x direction is almost conical. The achieved results can be used to optimization designing of military vehicles and employed for civil infrastructure. پرونده مقاله -
دسترسی آزاد مقاله
3 - Static Bending Analysis of Foam Filled Orthogonally Rib-Stiffened Sandwich Panels: A Mathematical Model
S Soleimanian A Davar J Eskandari Jam M Heydari BeniThe current study presents a mathematical modeling for sandwich panels with foam filled orthogonally rib-stiffened core using Heaviside distribution functions. The governing equations of the static problem have been derived based on classical lamination theory. The pres چکیده کاملThe current study presents a mathematical modeling for sandwich panels with foam filled orthogonally rib-stiffened core using Heaviside distribution functions. The governing equations of the static problem have been derived based on classical lamination theory. The present model contains three displacement variables considering all of the stiffness coefficients. A closed form solution using Galerkin’s method is presented for simply supported sandwich panels with foam filled orthogonally rib-stiffened core subjected to uniform lateral static pressure. Compared to previous researches, the present work is comprehensive enough to be used for symmetric, unsymmetric, laminated or filament wound panels with orthogrid stiffeners. The accuracy of the solution is checked both through comparisons with previous works, and the results of simulation with ABAQUS software. پرونده مقاله -
دسترسی آزاد مقاله
4 - Designing a prefabricated sandwich composite roofing system Made up of resisting facings and light-weight concrete core with truss-shaped connectors
Arash Totonchi Allah dad AhmadiIn this paper, a new roofing system is introduced, which is constructued using the precast composite sandwich panels. This roofing sandwich panels system consists of three kinds of precast concrete sandwich panels including capital panels, beam or between columns panels چکیده کاملIn this paper, a new roofing system is introduced, which is constructued using the precast composite sandwich panels. This roofing sandwich panels system consists of three kinds of precast concrete sandwich panels including capital panels, beam or between columns panels, and slab or middle panels. The panels are composed of three layers; A high strength reinforced concrete top layer. A thick layer of light-weight concrete as the intermediate layer or core. And a tensile resistant reinforced concrete bottom layer. The panels are connected together by special connectors at the edges.In this research, the influence of shear connector stiffness is studied which is measured according to their diameter on ultimate resistant and combined performance of the panels. The results of finite element analysis by ABAQUS software show a logical behavior of load-deflectioncurves in shear connectors. Based on the economic and weight comparisons the dead and live loads,the proposed sandwich panel roofing is approximately 44 percent lighter than the conventional steel joist and concrete blocks. This comparison shows the superiority of this roofing system to joists and concrete blocks system and seems to be a good alternative for it. Due to the possibility of prefabrication and industrial production of the panels under factory conditions, and various other technical, economic, and constructional advantages of this roofing system, it is concluded that it can be viable substitute for current roofing systems in low to high-rise buildings and can save a considerable amount of material, labor, time, and cost in building construction. پرونده مقاله -
دسترسی آزاد مقاله
5 - Numerical Study of the Effect of Temperature Changes on the Failure Behavior of Sandwich Panels with Honeycomb Core
Ismaeil ‎ Eynali Seyed Alireza Seyed RoknizadehIn this paper, failure modes of sandwich panels are investigated numerically using finite element method. For this purpose, four sandwich beams of GFRP laminateskins and Nomex honeycomb core are considered. The models have been chosen so that they could cover all failur چکیده کاملIn this paper, failure modes of sandwich panels are investigated numerically using finite element method. For this purpose, four sandwich beams of GFRP laminateskins and Nomex honeycomb core are considered. The models have been chosen so that they could cover all failure modes according to available experimental failure mode maps. Models are created and analyzed based on standard 3-points bending test, using ASTM standard C393-62. In order to investigate the effect of loading and sandwich panelparameters on failure behavior, finite element analysis has been utilized. The results are verified by comparing experimental and theoretical results. The constructed failure mode map shows dependence of failure mode on the ratio of skin thickness to span length, and honeycomb relative density. To Then, effect of temperature on the failure modes ofsandwich panels, has been investigated. Results show that failure modes haven’t depended on environment temperature and failure load decreases by increasing environmentaltemperature. The slope of reduction is a function of beam geometrical parameters.Depending on the parameters, the failure loads decrease between 10% to 40% byincreasing environmental temperature. پرونده مقاله -
دسترسی آزاد مقاله
6 - Experimental Investigation and Numerical Simulation of the Mechanical Behavior of a Novel Honeycomb Core Sandwich Panels Formed by Hydroforming Process
Javad Shahbazi karami Nazanin Kafaei Kavoshian Afshin Kazerooni Akbar Ghazi Mir SaeedSandwich panel with central core honeycomb aluminum as one of the main shielding structures because of their high strength-to-weight ratio and improved energy absorption capacity, has been attracted the attention of many researchers and practitioners in recent years. Th چکیده کاملSandwich panel with central core honeycomb aluminum as one of the main shielding structures because of their high strength-to-weight ratio and improved energy absorption capacity, has been attracted the attention of many researchers and practitioners in recent years. This paper initiates and presents a new type of central core honeycomb formed by hydroforming process. The study is augmented by a numerical and experimental work on flexural behavior of sandwich panel structures made of aluminum alloy and different cores such as aluminum, polyurethane foams, PVC, silicone and carbon fiber. Firstly a numerical simulation by ABAQUS software was run, then prepared samples were tested and related force-displacement diagrams were depicted from results. Comparing the corresponding diagrams obtained from simulation with that of the results of experimental investigation, high flexural strength of the sandwich panels with proposed honeycomb core relative to a three-layer sheet as well as a very high flexural strength of suggested sandwich panel with honeycomb core filled with carbon fiber against other samples of honeycomb was observed. Finally, comparing the experimental results with numerical simulations indicates acceptable conformity. پرونده مقاله -
دسترسی آزاد مقاله
7 - بررسی عملکرد سقفهای ساندویچ پانلی تحت بار انفجار به روش اجزاء محدود
ناصر احدی محمدعلی لطف الهی یقینامروزه با گسترش حملات انفجاری به ساختمان ها در جهان، بررسی دقیق رفتار سازه ها تحت اثر بارهای انفجاری یک ضرورت محسوب میشود. انفجار واکنشی است که در آن نرخ سوختن مواد با سرعتی به مراتب بیشتر از سرعت صوت انجام میشود که در نتیجه آن، گرادیان دما و فشار بسیار بالا ایجاد شده چکیده کاملامروزه با گسترش حملات انفجاری به ساختمان ها در جهان، بررسی دقیق رفتار سازه ها تحت اثر بارهای انفجاری یک ضرورت محسوب میشود. انفجار واکنشی است که در آن نرخ سوختن مواد با سرعتی به مراتب بیشتر از سرعت صوت انجام میشود که در نتیجه آن، گرادیان دما و فشار بسیار بالا ایجاد شده و موج شوک بلافاصله تولید و با سرعت بسیار بالا منتشر می شود. در این تحقیق با توجه به اهمیت موضوع به بررسی رفتار سقفهای ساندویچ پانلی تحت بارهای انفجاری کانوپ با استفاده از نرم افزار آباکوس 2016 پرداخته خواهد شد. بدین ترتیب که جهت اعتبار داشتن نتایج نمونههای عددی، در ابتدا به صحت سنجی نتایج یک نمونه از مقاله مرجع پرداخته و بعد از درستی نتایج، به مدلسازی نمونههای عددی به تعداد 6 مدل و استخراج نتایج در نرم افزار اکسل اقدام خواهد شد.. در این تحقیق نمونههای عددی شامل دو گروه سقف ساندویچ پانل فولادی بوده که در فاصله سخت کنندههای داخلی با هم فرق دارند. هر دو گروه تحت بارهای انفجاری معادل 1 و2 و3 کیلوگرم TNT در فاصله 20 سانتیمتری از مرکز سقف قرار گرفته و تاثیرات بار انفجاری بر روی توزیع تنش و جابجاییهای ایجاد شده در نمونهها را مورد بررسی قرار داده خواهد شد. مطابق انتظار با توجه به نمونه ها با ثابت بودن ماده منفجره و افزایش فاصله از سطح پانل میزان جابجایی و تنش های وارده به پانل کمتر شده و همچنین با ثابت ماندن فاصله ماده منفجره از روی سطح پانل و افزایش میزان ماده انفجاری، جابجایی و تنش وارده به پانل نیز افزایش یافته است. پرونده مقاله
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