Master Degree / Yüksek Lisans Tezleri
Permanent URI for this collectionhttps://hdl.handle.net/11147/3008
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Master Thesis Analysis of the Carcked Infinite Hollow Cylinder With Loading on Crack Surfaces(Izmir Institute of Technology, 2009) Avcı, Fatih; Artem, Hatice SeçilIn this study, the cracked infinite hollow cylinder with an axisymmetric crack of width (b-a) is considered. The ring-shaped crack is located at the symmetry plane. Surfaces of the crack are subjected to the distributed compressive loads. The outer surface of the cylinder is rigid and the inner one is stress free. The material of the cylinder is assumed to be linearly elastic and isotropic. Integral transform techniques are used for the solution of the field equations. The resultant singular integral equation in terms of crack surface displacement derivative is converted to a system of linear algebraic equations by using Gauss-Lobatto, Gauss-Jacobi and Gauss-Laguerre integration formulas. The stress intensity factors at the tips of the crack are numerically calculated for uniform and linear load distributions on crack surfaces. Some results are presented in graphical and tabular forms.Master Thesis Design of Parallel Micromechanisms for Knotting Operation(Izmir Institute of Technology, 2009) Çankaya, Cüneyt; Alizade, RasimThis thesis covers a study on the design of micromechanisms which are capable of imitating the knotting operation and their applications on carpet manufacturing.For this purpose, motion generation synthesis of a planar two degree-of-freedom serial manipulator is performed for a given path by using interpolation approximation. For a given four points, four design parameters are solved as a result of non-linear equations. Also, analysis of each stages of knotting operation is kinematically performed for the design of a cam-actuated mechanism which is designed as an alternative concept. Results of these analysis are used for the design of cam profiles those of which actuates the manipulators.After design stage of knotting micromechanisms, fully automated carpet loom design is introduced for a real-life experiment of designed mechanisms. Finally, assembly considerations of carpet loom and knotting mechanisms are given for carpet manufacturing purpose.Master Thesis Experimental Investigation of Heat and Fluid Flow in an Actuated Impinging Jet Flow(Izmir Institute of Technology, 2009) Bilgin, Necati; Özkol, ÜnverThe objective of this work is to how the surface heat transfer and flow characteristics can be affected by jet flow by excitation of which changes the turbulence characteristics of the flow. Main body of this work is experimental analysis; nevertheless some simple numerical analysis is also presented in order to make some comparisons. The hot-wire measurements and flow visualizations are performed. As a flow actuator a loudspeaker is used once the piezo-electric benders were found to be unsuccessful. Acoustic (pressure) wave generated by the loudspeaker travels along the flow system and reaches the jet nozzle where it generates an oscillating component on the mean nozzle velocity. Parameters used on this study are shortly Re.10000, dimensionless jet to plate distance is equal to 6, as a non-dimensional excitation frequency Strouhal number is changed in the range of 0.St.1, and as for the excitation amplitude, voltages sent to the 20X amplifier are 0.5V, 1.0V and 1.5V.Master Thesis Modelling and Simulation of Metal Cutting by Finite Element Method(Izmir Institute of Technology, 2009) Kılıçaslan, Cenk; Yardımoğlu, BülentMetal cutting is one of the most widely used manufacturing techniques in the industry and there are lots of studies to investigate this complex process in both academic and industrial world. Predictions of important process variables such as temperature, cutting forces and stress distributions play significant role on designing tool geometries and optimising cutting conditions. Researchers find these variables by using experimental techniques which makes the investigation very time consuming and expensive. At this point, finite element modelling and simulation becomes main tool. These important cutting variables can be predicted without doing any experiment with finite element method. This thesis covers a study on modelling and simulation of orthogonal metal cutting by finite element method. For this purpose, orthogonal cutting simulations of AISI 1045 steel are performed and model used in simulations is validated. At first step, effects of work piece flow stress and friction models on cutting variables such as cutting forces, chip geometry and temperature are investigated by comparing simulation results with experimental results available in the literature. Then, mechanical and thermal analyses are performed. Lastly, effects of rake angle and tool tip radius on strain, temperature and stress distributions are investigated.Master Thesis A Research on Design of Heating, Ventilation and Air Conditioning of Hygienic Spaces in Hospitals(Izmir Institute of Technology, 2008) Anıl, Orkun Baki; Mobedi, MoghtadaThere are various sterile spaces in hospitals which are highly at risk in terms of infection. HVAC systems play an important role on the infection risk in sterile spaces.HVAC systems for sterile spaces focus on number of particles, number and types of microorganisms, pressure difference between the sterile and its neighboring spaces, supply air velocity and air distribution in addition to the comfort parameters which are temperature, relative humidity and fresh air rate. Therefore, the design of HVAC systems for sterile spaces is more difficult and complicated compared to the comfort applications.This study firstly reviews the design parameters of HVAC systems of sterile spaces in hospitals. A literature survey is conducted about the effects of the design parameters on infection transmission in sterile spaces. Also a literature survey on various standards and design guidelines for HVAC design parameters of sterile spaces used by different countries is performed. Secondly, an experimental study was conducted in an operating room to reveal the system performance during operation.The reviewed standards and guidelines are compared via tables. The weak and strong points of the reviewed references are noted. Despite well known effects of HVAC systems on infection transmission, significant differences among standards and guidelines are observed. Based on the obtained experimental results, considerable differences of design parameters between .in operation. and .at rest. states were observed.Master Thesis A Qualitative Machine Health Assessment by Running Quality Index(Izmir Institute of Technology, 2008) Önder, Olcay; Güden, MustafaMechanical components have limited life which is strongly related to the usage rate and operational conditions. Two parts could appear similar but actually not have the similar performances, because they had different usage rate, age, applied force and etc. during their life cycles. In this thesis, a new method that help to define the failure risk of mechanical components after customer utilization. The coding of Running Quality Index was performed in MATLAB program. The developed index summarizes all performance history of mechanical component/or part into a single number. A shaft test rig was designed to simulate force and number of cycle effects on the quality index. Tensile tests were conducted on St-37 steel samples exposed to varying forces, number of cycles and heat treatment to calculate Running Quality Index. The experimental results showed that increasing total number of cycles or repeated forces decreased the remaining life of samples. The developed quality index resulted in more risk penalty points for increasing number of cycles and repeated forces.Master Thesis Mechanical Behavior and Modeling of Honeycomb Cored Laminated Fiber/Polymer Sandwich Structures(Izmir Institute of Technology, 2008) Sezgin, Fatma Erinç; Tanoğlu, MetinThe use of composite sandwich structures is increasing in aerospace and civil infrastructure applications due to their high flexural and transverse stiffness and light weight. Considering different mechanical properties, sandwich structures can be manufactured from various core and facesheet materials.In this study, hand lay up technique was used for the fabrication of sandwich structures made of polypropylene based honeycomb core and glass fiber reinforced polymer (GFRP) facesheets. The non-crimp glass fibres and epoxy matrix were used for the production of GFRP laminates. The variation of the core thickness was the major parameter for considering the mechanical behaviour and failure mechanisms of the sandwich structures. Based on flatwise compression tests, an increase in compressive modulus and strength was observed with the increase of core thickness. For edgewise compression tests, peak loads up to crush of the sandwich panel was discussed by means of core thickness. According to the three point bending tests, a decrease in core shear stress and facesheet bending stress was observed as the core thickness increases.The modeling of sandwich structures were also carried out with three dimensional finite element models. The ANSYS 11 software was used for utilizing the test data in order to predict the mechanical behavior of the sandwich structures. In the finite element analysis, the test results of each constituent were employed as the input data for ANSYS. The experimental data and predicted results were found to be in good agreement in the elastic region, therefore the model can be used to predict the behavior of similar structures in elastic region.Master Thesis Development and Design of Closed-Cell Aluminum Foam-Based Lightweight Sandwich Structures for Blast Protection(Izmir Institute of Technology, 2008) Ergönenç, Çağrı; Taşdemirci, AlperBlast performance and energy absorption capability of closed-cell aluminum foam based lightweight sandwich structures were investigated by a coupled experimental and numerical technique to find out the effect of face and core material on the blast response. Split Hopkinson Pressure Bar Testing Method (SHPB) was used to characterize the mechanical properties of constituents of the sandwich structures at high strain rates. A SHPB set-up, a high strain rate testing apparatus which can successfully create blast load at laboratory scales, was built at IZTECH on behalf of a TUBITAK project (106M353). The high strain rate test data were used as an input for the numerical models. Closed-cell aluminum foam was chosen as core material for sandwich structures owing to its high energy absorption characteristic while deforming plastically. Finite element modeling of sandwich structures subjected to blast loading were performed for different core and face thicknesses and face materials in order to investigate their effects on the blast load mitigation.Experimentally and numerically revealed conclusions are; sandwich structures absorbed more energies than the bulk materials from %50 to %150 when appropriate combinations of core and face materials are used. Numerical simulations showed that 6.3 and 7.2 cm thick foam interlayer are the most efficient foam thicknesses for a 9 cm sandwich plate against 10 kg TNT blast load. Another important conclusion is for the same blast threat i.e. 10 kg of TNT, AISI 4340 Steel is the most effective face material.Master Thesis Design and Manufacturing of a Fireproof Fire Rescue Robot(Izmir Institute of Technology, 2008) Tok, Özge; Keçeci, Emin FarukThe aim of this thesis is to design and manufacture fireproof fire rescue robot for extinguishing fire. The robot is designed and manufactured to go in the middle of fire, extinguish it and send images from incident area by using a camera to increase knowledge about fire behavior. This robot makes it possible to extinguish fire without spreading in the shortest time. This will reduce the risk of injury and number of casualties for firefighters as well as for the possible victims. The robot can also decrease the monetary losses which increase considerably as fire duration increases.For designing the fireproof fire rescue robot three dimensional solid modeling computer program was used. The semi-autonomous robot is powered by two DC electric actuators. It goes on the ground with tracking system which is manufactured by using sprockets and chains. To prevent possible damages that may be incurred by heat, the robot was covered with a ceramic fiber paper that has very low thermal conductivity.In addition to mechanical design of the fireproof fire rescue robot, two electronic circuits are mounted in order to control actuators and solenoid valve of the extinguisher.Furthermore, in order to control actions of the robot remotely by the operator, two remote controls are used at different frequencies.As a result of this thesis; a fireproof fire rescue robot is designed and manufactured to be used in fire incidents. Also some ideas were expressed to improve the fireproof fire rescue robot by gained experience throughout the thesis.Master Thesis Robotization of Hand Woven Carpet Technology Process(Izmir Institute of Technology, 2008) Selvi, Özgün; Alizade, RasimThis thesis covers a study on the structural design of new overconstrained mechanisms and manipulators and their application to the robotization of hand woven carpet technology process.Moreover, recurrent vector equations are investigated for the synthesis of linkages, and used for the design of new mechanisms with linear-angular conditions in the subspace with general constraint one. These conditions are generalized for defining the structural groups of subspace ..5 and these structural groups are used both for the creation of new parallel manipulators and new serial-parallel platform manipulators.After investigating hand woven carpets, the knowledge gained during the structural design of mechanisms is applied to the robotization of hand woven carpet technology process. Finally, design of carpet weaving robot is introduced.