Sharif Digital Repository

In this research, the effect of various parameters on the behavior of silty sands is evaluated under special loading conditions. To evaluate these parameters, the hollow cylinder apparatus of the Advanced soil mechanics at Sharif University is used. In this research the effect of principal stress directions, initial anisotropic consolidation, silt content, effective mean normal consolidation stress and intermediate principal stress are studied on the behavior of silty sands including the strength and pore water pressure. In order to evaluate these parameters, the specimens are made with wet tamping method with 0, 10, 20, 30 and 40 percent of silt. Before applying shear load to specimen, the... 

The objective of this project is numerical simulation of air flow and heat transfer between two horizontal concentric cylinders with rotation of inner cylinder and inertia of outer cylinder grooves on the inner cylinder. In this study, the air, meanwhile rotational motion by the inner cylinder will enter into the annular space between two cylinders with certain flow rate. It can be mentioned to cooling of power plant generators, Electric motors and rotating machines among usages of air flow between two cylinders. In this article the objective is calculation of pressure drop and Nusselt number, temperature distribution on the inner cylinder under conditions of constant temperature of... 

Despite of passing many years from invention of Computational Fluid Dynamics (CFD), simulation of the fluid-solid interfaces and free surfaces are still completely challenging and progressive problems. In addition knowing and understanding nanotechnology huge applications,modeling of nano-fluids have been became a priority for researchers. Adding importance of Non-Newtonian fluids (especially polymeric solutions) to this two subjects, triangle topics of this research becomes vivid. In this research tried to consider and examine behavior of Newtonian,Generalized-Newtonian, Viscoelastic and nano-filled viscoelastic fluids in one and two phase mediums. we followed mesh free methods which are... 

AS5U3G and AS7U3G are two prevalent types of alloy which are used in producing cylinder head. In this research AS5U3G alloy is studied. Gravity casting is one of the method of producing this part. Produced porosities in cylinder head casting process, cause leakage in this part. In order to solve this problem, some actions have been taken that we can divide them into quality operations improvement of melt and making changes in casts. The sampling is done in four levels to evaluate the gas porosity and shrinkage. In these levels, pressure and degassing duration and strontium's modifying in a fixed temperature have been evaluated. Based on reports by comparing density of relative samples, it... 

In many of the geotechnical engineering projects, such as embankments in earth dams and roads, the soil bears anisotropic loading. Even that the behavior of this material depends on the anisotropic loading, not many researches have investigated the effects of this phenomenon. The main objective of this research is investigation the effect of anisotropic loading induced by mean principal stress parameter under unsaturated conditions. Hence, shear strength of firoozkooh silt, in terms of deviatoric stress at failure under monotonic loading under different values of intermediate stress parameter and saturation degree have been studied. For this purpose, silty samples have been prepared with... 

In the present project an analytical model is proposed for the instability of spinning composite cylindrical shells partially filled with fluid. For this purpose, using the linearized Navier-Stokes equation for the incompressible flow, a 2-D model is developed for fluid motion at each section of the cylinder. The resultant pressure exerted on the cylinder wall as the result of the fluid motion, are calculated in terms of elastic displacements of the cylinder. Applying the Hamilton principle, the governing equations of motion of the cylinder are derived and then combined with the equations describing the fluid pressure to obtain the coupled-field equations of the structural-fluid motion.... 

Nowadays best using of fossil fuels sources of the country (and) importance of comparison against lack of capacity in petrol production make determined the programmers and the directors to foresee and design expanded programs of the goals, to use natural gas for car fuels. To reach fulfillment of these programs, the confirmed needs of the natural gas cylinders are improved and make it essential to invest on producing compressive natural gas cylinders. In this way economical and technical change researches has been done in order to construct on department to produce 200,000 compressive natural gas cylinders in a year during two sets.(shifts) According to the results of technical researches... 

In many of the geotechnical engineering projects, such as embankments in earth dams and roads, the soil bears anisotropic loading. Even that the behavior of this material depends on the anisotropic loading, not many researches have investigated the effects of this phenomenon. The main objective of this research is investigation the effect of anisotropic loading induced by rotation angel of principal axes parameter under unsaturated conditions. Hence, shear strength of firoozkooh silt, in terms of deviatoric stress at failure under monotonic loading under different values of rotation angel of principal stress axes parameter and confining stress have been studied. For this purpose, silty... 

In this thesis, an analytical method is presented to investigate the steady state thermal and mechanical stresses of a thick hollow infinite cylinder made of porous piezoelectric that composed of functionally graded materials. So, according to the thermal and mechanical loads on internal and external surfaces of infinite cylinder, the porosity, temperature and material property distribution are considered as non-symmetric, two-dimensional (radial and circumferential) variables. The approach is presented to investigate this problem, by employing the method of separation of variables, Euler equations and complex Fourier series. Firstly, the governing equations of problem are extracted and... 

In this study, using Reddy's layer-wise theory, thermal and rotational inter-laminar stress distribution within cylindrical composite shells with different boundary conditions is analytically studied. Convergence of the layer-wise theory is also studied and the numbers of sub-layers are determined so that efficient and accurate results can be achieved by this method. In order to assess the validity of layer-wise theory, results of this method are compared with results obtained by elasticity theory, for two sets of boundary conditions. It is observed that depending on the shell layer stacking, loading and boundary condition type, each of inter-laminar stresses may be the critical stress... 

In this research, first, the performance map and surge line of 46M6 and 46MB8 multi-stage radial compressors, which have 6 and 8 stages, respectively, have been estimated and invarianted. Invarianting the performance map makes the performance curve and surge line of the compressor, unchanged from input conditions, including molecular weight, which is very important for control systems. Then, the hydrodynamic circuit of Compressor System C-3002 of Nouri Petrochemical Company was modeled according to the characteristics of its components by solving equations in MATLAB software. main working condition of the hydrodynamic circuit is close to Start of Life operating condition which has a... 

In this thesis velocity and temperature fields of concentric cylinders with rotation of inner wall have been investigated numerically. Air enters the gap between cylinders and attains fully developed in both velocity and temperature fields after certain lengths. Adiabatic and constant heat flux boundary conditions have been applied and Nusselt number was calculated. In order to analyze the variations of velocity and temperature fields, different angular velocities at constant axial Reynolds number and different axial velocities at constant angular velocity have been investigated. The turbulent stresses were approximated with k ?? ... 

Direct Reduction of magnetite concentrate with thermal coal in concentric cylindrical arrangement has been investigated. At first, thermal behavior and physical and chemical properties of 3 type of coals from different coal mines of Iran in a thermal treatment similar to pre heating section of tunnel kiln direct reduction of Iron were investigated.Study of changes in reactivity and calorific values of coal in addition to providing a fundamental understanding of coal performance in the thermal process of reduction set a base for investigation of recycling of unburnt coal in the reduction process. Thermogravimetric data for coal devolatilization in three heating rates yielded an activation... 

The purpose of this study is to numerically investigate the Vortex-Induced Vibration (VIV) around the cylinder, which occurs in many engineering structures, including offshore structures, offshore risers, deep-sea pipelines, bridges, cables, and tall buildings. This phenomenon is non-linear and self-limitting and is the major cause of fatigue and failure in engineering structures. At the same time, it is possible to harvest Aquatic Clean Energy from Vortex-Induced Vibration. This research investigates the single degree of freedom and two degrees of freedom oscillator. The numerical model is validated using an experimental model in the Sharif University of Technology's advanced hydraulics... 

In this study, by performing a series of experiments, the effect of the presence of cylinders on the formation of vortices and the interaction of cylinders on each other and, finally, transverse propagation in a steady flow are investigated. The cylinder cylinders that are in the direction of the motion of the water, have a significant effect on the hydrodynamic aspects and propagation in these streams. In the pattern of flow around cylindrical cylinders, with increasing Reynolds number, the vortex behind the stem begins to oscillate and when they reach, vortices flow into the stream. The flow velocity field, the formation and vortex fluctuation, affects the process of particle propagation... 

Direction of loading and magnitude of the intermediate principal stress have significant effect on the soil responses. In many of in-situ loading the direction of major principal stress is not coincide to the deposition direction of the soil. Also, the magnitude of the intermediate principal stress should be exerted in the three dimensional loading condition. A reliable assessment of the soil behavior and a good estimation of the soil parameters need to do tests in similar condition with in-situ. So the testing apparatus should be able to control the loading direction in various stress paths. Typical equipments used in the geotechnical laboratory have not the ability to control the magnitude... 

Structural efficiency is a primary concern in today’s aerospace and aircraft industries. This brings about the need for strong and light weight structures. To increase the strength of a panel without considerable increase in its weight, we may use a lattice of stiffeners which may have shells connected to one side of the lattice or both sides of it. These structures are usually called grid stiffened structures. Aircraft fuselage and launch vehicle fuel tanks are some of the many applications of these structures in aerospace and aircraft industries. These structures include two major groups; isogrids (grid stiffened structures with equivalent isotropic properties) and orthogrids (grid... 

Single-layer steel grid shell structures are a good structural solution to new buildings by specific properties that are required by long-span structures and provide at the same time the opportunity to produce immense verity of design shapes and free form architecture; complex curved surfaces expect to be covered with low weight material. A grid shell is essentially a shell with its structure concentrated into individual linear element in relatively thin grid compared to the overall dimension of the grid shell. This research investigates single-layer grid structures with emphasis on design of load details. The application of single-layer for transparent structures enhances use of glazed... 

In this thesis the dynamic behavior of the thick-walled shell with variable thickness is investigated. Such structures are used in a variety of industries including aerospace, oil, gas and petro-chemistry. In this study, the dynamic behavior of a rotating truncated conical thick-shell with various geometries is investigated. For this purpose, modal analysis is performed using the refined finite element method. Then,the natural frequencies and corresponding mode shapes are calculated for several different geometries. Also, the relationship between geometrical variables such as thickness, the ratio of length to radius, ratio of cross-sectional radius and so on, with the natural frequency of... 

In many of the geotechnical engineering projects, such as construction of embankments and roads, soil is compacted with different water contents. Difference in compaction water content leads to different dynamic behaviors under cyclic loadings like earthquake and traffic. On the other hand, the magnitude and the direction of principal stresses on soil element, affect the dynamic response of the soil. The main objective of this research is to study the effects of compaction water content on dynamic properties of soil in anisotropic loading conditions. Therefore, the dynamic parameters of Babolsar sand, including shear strain amplitude, shear modulus and damping ratio under induced anisotropic...