Shear modulus

حرية الوصول المقاله

1 - اثر ناهمگنی مصنوعی دانسیته بر مدول‌برشی دینامیک چوب بلوط بلند مازو (<i>Quercus castaneifolia</i>)
مصطفی کهن ترابی امیر هومن حمصی محمد طلایی پور مهران روح نیا بهزاد بازیار

10.30495/jrnr.2021.18360

در این تحقیق به بررسی تاثیر ایجاد ناهمگنی مصنوعی دانسیته در ناحیه ابتدایی و میانی تیرهای بلوط بلند مازو (Quercus castaneifolia) با بررسی تغییرات حاصل در مدول‌برشی دینامیک حاصل از روش ارتعاش خمشی آزاد در تیر دو سر آزاد پرداخته ‌شده است. بدین منظور تعداد 10 آزمونه از گون أکثر

در این تحقیق به بررسی تاثیر ایجاد ناهمگنی مصنوعی دانسیته در ناحیه ابتدایی و میانی تیرهای بلوط بلند مازو (Quercus castaneifolia) با بررسی تغییرات حاصل در مدول‌برشی دینامیک حاصل از روش ارتعاش خمشی آزاد در تیر دو سر آزاد پرداخته ‌شده است. بدین منظور تعداد 10 آزمونه از گونه بلوط با ابعاد 720× 40× 20 میلی &lrm;‌ متر (طولی، شعاعی و مماسی) جهت تعیین مدول‌برشی در تیرهای اولیه مورد آزمون ارتعاش خمشی آزاد در تیر دو سر آزاد قرار گرفتند. پس ‌از آن آزمونه‌ ها به دو گروه تقسیم ‌شده و از گروه اول بلوک‌ هایی به ابعاد 40×40×20 میلی متر از قسمت ابتدایی و از گروه دوم بلوک‌ هایی با ابعاد ذکرشده از قسمت میانی استخراج ‌شده و توسط چسب پلی وینیل استات به یکدیگر متصل شده و پس از برقراری اتصال آزمون ارتعاش خمشی آزاد مجددا بر روی آزمونه‌ ها صورت پذیرفت. پس ‌از آن بلوک‌ های بلوط از محل اتصال خارج ‌شده و در دو مرحله بلوک‌هایی از دو گونه صنوبر (Populus nigra) و انجیلی (Parrotia persica) در آنها جایگزاری شده و به‌منظور تاثیر ناهمگنی ایجاد شده توسط هر یک از بلوک ‌های جایگزین شده بر مقادیر مدول‌برشی، آزمون ارتعاش خمشی بر روی آنها صورت پذیرفت. نتایج حاکی از آن بود که ایجاد ناهمگنی مصنوعی دانسیته در ناحیه ابتدایی تیر توسط هر سه گونه بلوط، صنوبر و انجیلی تاثیر معنی‌ داری بر مقادیر مدول ‌‌برشی دینامیک ندارد، درحالی‌که ایجاد ناهمگنی در قسمت میانی تیر باعث افت معنی‌ دار مقادیر حاصل از این فاکتور شده است. تیرهای ناهمگن شده توسط گونه انجیلی بیشترین و تیرهای ناهمگن شده توسط گونه بلوط با کمترین درصد افت در مقادیر مدول ‌برشی دینامیک مواجه شدند. تفاصيل المقالة

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2 - Mathematical Modeling of Thermoelastic State of a Thick Hollow Cylinder with Nonhomogeneous Material Properties
V. R Manthena N.K Lamba G.D Kedar

The object of the present paper is to study heat conduction and thermal stresses in a hollow cylinder with nonhomogeneous material properties. The cylinder is subjected to sectional heating at the curved surface. All the material properties except for Poisson’s ra أکثر

The object of the present paper is to study heat conduction and thermal stresses in a hollow cylinder with nonhomogeneous material properties. The cylinder is subjected to sectional heating at the curved surface. All the material properties except for Poisson’s ratio and density are assumed to be given by a simple power law in the axial direction. A solution of the two-dimensional heat conduction equation is obtained in the transient state. The solutions are obtained in the form of Bessel’s and trigonometric functions. For theoretical treatment, all the physical and mechanical quantities are taken as dimensional, whereas we have considered non-dimensional parameters, for numerical analysis. The influence of inhomogeneity on the thermal and mechanical behaviour is examined. The transient state temperature field and its associated thermal stresses are discussed for a mixture of copper and tin metals in the ratio 70:30 respectively. Numerical calculations are carried out for both homogeneous and nonhomogeneous cylinders and are represented graphically. تفاصيل المقالة

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3 - Thermoelastic Analysis of a Rectangular Plate with Nonhomogeneous Material Properties and Internal Heat Source
V. R Manthena N.K Lamba G.D Kedar

This article deals with the determination of temperature distribution, displacement and thermal stresses of a rectangular plate having nonhomogeneous material properties with internal heat generation. The plate is subjected to sectional heating. All the material propert أکثر

This article deals with the determination of temperature distribution, displacement and thermal stresses of a rectangular plate having nonhomogeneous material properties with internal heat generation. The plate is subjected to sectional heating. All the material properties except Poisson’s ratio and density are assumed to be given by a simple power law along x direction. Solution of the two-dimensional heat conduction equation is obtained in the transient state. Integral transform method is used to solve the system of fundamental equation of heat conduction. The effects of inhomogeneity on temperature and thermal stress distributions are examined. For theoretical treatment, all the physical and mechanical quantities are taken as dimensional, whereas for numerical computations we have considered non-dimensional parameters. The transient state temperature field and its associated thermal stresses are discussed for a mixture of copper and zinc metals in the ratio 70:30 respectively. Numerical calculations are carried out for both homogeneous and nonhomogeneous cases and are represented graphically. تفاصيل المقالة

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4 - The Validity Assessment of Laboratory Shear Modulus Using In-Situ Seismic Piezocone Test Results
Seyed Majdedin Mir Mohammad Hosseini A.A. Hajimohammadi

Seismic piezocone device (SCPTu) together with Resonant Column and Cyclic Triaxial test apparatus are employed to measure small strain shear modulus (G0) of carbonate sandy and clayey soils of southern coasts of Iran. A large area of southern regions of Iran is formed f أکثر

Seismic piezocone device (SCPTu) together with Resonant Column and Cyclic Triaxial test apparatus are employed to measure small strain shear modulus (G0) of carbonate sandy and clayey soils of southern coasts of Iran. A large area of southern regions of Iran is formed from clay, silt and sand. In this study, maximum shear modulus that is derived from both field (by seismic piezocone) and laboratory (by Resonant Column and Cyclic Triaxial) tests on soil samples from the southern region, indicated a meaningful effect of sample disturbance. Results show that in laboratory tests, loose samples tend to become denser and therefore exhibit greater stiffness whereas dense samples tend to become looser, showing a reduction in stiffness. According to the results of the present study, there are narrow limits of soils shear moduli for which the laboratory tests and the field measurements yield approximately the same amounts. This limit of shear moduli is about 30-50(MPa) for clay deposits and 70-100 (MPa) for sandy deposits. Since the shear moduli of soils in small strains can also be computed from the shear wave velocity, also correlations based on parameters derived from SCPTu test for shear wave velocity determination of sandy and clayey soils of the studied area are presented. This study shows that shear wave velocity can be related to both corrected tip resistance and total normal stress. Regarding the shear moduli and the damping ratio, due to the disturbances of the stiff deposits in the sampling process and great deviations of laboratory results from field results, the laboratory measurements of these parameters out of the above limits are not recommended. تفاصيل المقالة

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5 - A mathematical model for optimization of strength of concrete: A case study for shear modulus of Rice Husk Ash Concrete
O.S Ogah

Rice Husk Ash (RHA) is natural Pozzolan containing reactive silica and/or aluminum. When the material is mixed with lime in powdered form and in the presence of water, it will set and harden like cement. This work uses Osadebe’s optimization model to optimize the أکثر

Rice Husk Ash (RHA) is natural Pozzolan containing reactive silica and/or aluminum. When the material is mixed with lime in powdered form and in the presence of water, it will set and harden like cement. This work uses Osadebe’s optimization model to optimize the shear modulus of concrete made from RHA. The strengths predicted by the model are in good agreement with their corresponding experimentally obtained values. With the model, any desired strength of hardened concrete, given any mix proportions, is easily evaluated. The average Poisson ratio and mean shear strength for the concrete are found to be 0.26 and 5.5 N/mm2 respectively. تفاصيل المقالة

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