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Finite Element Analysis Of A Micro Satellite Structure Under Vibration Induced Loads During LaunchOntac, Suat 01 May 2008 (has links) (PDF)
This study mainly covers the finite element analysis of a micro satellite structure by considering the vibration effects at the time interval from the launching to the Earth&rsquo / s orbit landing.
Micro-satellites have a great importance in the satellite industry and several developing countries deal with micro-satellite design and production. Turkey is one of these countries by conducting new satellite projects. RASAT project is one the continuing micro-satellite project, which has being developed by TÜ / BiTAK Space Technologies Research Institute. In this thesis, the RASAT satellite is taken as the model for the study. On this model, many mechanical design studies which are performed according to the specified requirements and constraints are verified by finite element analyses. These analyses cover all the essential vibration loads during launching. In the study, firstly, a finite element model of RASAT is prepared. Then, the essential analyses are performed according to the specifications required by the launchers. In the analyses, commercially available finite element software is used.
Finally all the results obtained from the finite element analyses are compared with the predefined requirements and constraints. The results show that the structural design verification regarding the reliability of the structure for the desired mission has been successfully completed.
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Shape Optimization Of An Excavator Boom By Using Genetic AlgorithmUzer, Cevdet Can 01 June 2008 (has links) (PDF)
This study concerns with the automated structural optimization of an excavator boom. The need for this work arises due to the fact that the preparation of the CAD model, performing finite element analysis and model data evaluation are time consuming processes and require experienced man power. The previously developed software OptiBOOM, which generates a CAD model using a finite set of parameters and then performs a finite element analysis by using a commercial program has been modified. The model parameter generation, model creation, analysis data collection and data evaluation phases are done by the Python and Delphi based computer codes. A global heuristic search strategy such as genetic algorithm is chosen to search different boom models and select an optimum.
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Developing A Four-bar Mechanism Synthesis Program In Cad EnvironmentErener, Kaan 01 June 2011 (has links) (PDF)
Flap, aileron, rudder, elevator, speed brake, stick, landing gear and similar movable systems used in aerospace industry have to operate according to the defined requirements and mechanisms used in those systems have to be synthesized in order to fulfill those requirements. Generally, without the use of synthesis tools, synthesis of mechanisms are done in CAD environment by trial-error and geometrical methods due to the complexity of analytical procedures. However, this approach is time consuming since it has to be repeated until the synthesized mechanism has suitable mechanism properties like transmission angle and connection points. Due to above reasons, a software developed for synthesis of mechanisms within the CAD environment can utilize all the graphical interfaces and provides convenience in mechanism design.
In this work, it is aimed to develop a four-bar mechanism synthesis tool which is compatible with CATIA V5 by considering the requirements of aerospace industry. This tool performs function, path and motion synthesis and shows suitable mechanisms in CATIA according to input obtained from CATIA and mechanism properties.
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Feature Based Design Of Rotational Parts Based On StepFidan, Tahir 01 December 2004 (has links) (PDF)
The implicit and low-level part definition data, provided by geometric modeling cannot be used by downstream applications. Therefore, feature based modeling concept has been introduced to integrate CAD and downstream applications. However, due to the lack of implicit and explicit standard representations for features and unmanageable number of possible predefined features without standardization, feature based modeling approach has proved to be inadequate. STEP AP224 provides a standard for both implicit and explicit representations for manufacturing features. This thesis presents STEP AP224 features based modeling for rotational parts. The thesis covers features extracted from STEP AP224 for rotational parts and their definitions, classifications, attributes, generation techniques, attachment methods and geometrical constraints. In this thesis a feature modeler for rotational parts has been developed. STEP AP224 features generated are used as the basic entities for part design. The architecture of the proposed system consists of two three phases: (1) feature library, (2) feature modeler and (3) preprocessor. Preprocessor responsible from STEP-XML data file creation. The data file created can be used in the integration CAPP/CAM systems without using a complex feature recognition process. An object-oriented design approach is used in developing the feature modeler to provide incremental system development and reusability.
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Kinematic Design Of Mechanisms In A Computer Aided Design EnvironmentDemir, Eralp 01 May 2005 (has links) (PDF)
CADSYN (Computer Aided Design SYNthesis) is a visual, interactive computer
program working under Computer Aided Design (CAD) enviroment, which
accomplishes the synthesis and analysis of planar four-bar mechanisms. The
synthesis tasks are motion generation, path generation and function generation.
During synthesis, the dyadic approach is utilized which introduces vector pairs and
complex number algebra to model the motion. The possible solutions can be limited
for link dimensions, the center circle point curves within a certain region,
transmission angle characteristics, branch and order defects. The designed
mechanism can be analyzed for velocity, acceleration and transmission angle and any
of the data can be exported to Excel® / for further analysis.
The software is designed to provide the user maximum feasible number of solutions.
In four multiply separated position synthesis, if there is flexibility in the value(s) of
one or any number of input parameter(s), designer can obtain different Burmester
curves by changing those parameter(s). Designer can also simulate the kinematics of
the mechanism by using drawing functions that are available from the CAD
iv
enviroment at any time. Drawing parts in the design plane can be attached to any link
of the mechanism and can be simulated throughout the motion as part of the link it is
attached. As a whole, this computer program is designed to satisfy the needs of
mechanism designers while working in CAD enviroment.
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Design Of A Connected Pipe Test Facility For Ramjet ApplicationsSarisin, Mustafa Nevzat 01 May 2005 (has links) (PDF)
ABSTRACT
DESIGN OF A CONNECTED PIPE TEST FACILITY
FOR RAMJET APPLICATIONS
SARISIN, Mustafa Nevzat
M.S., Department of Mechanical Engineering
Supervisor: Asst. Prof. Dr. Abdullah ULAS
Co-Supervisor: Prof. Dr. Kahraman ALBAYRAK
April 2005, 164 pages
Development of the combustor of a ramjet can be achieved by connected pipe testing. Connected pipe testing is selected for combustor testing because pressure, temperature, Mach number, air mass flow rate can be simulated by this type of testing. Real time trajectory conditions and transition from rocket motor (booster) to ramjet operation can also be tested. The biggest advantage of connected pipe testing is the low operation cost and simplicity. Air mass flow rate requirement is less than the others which requires less air storage space and some components like supersonic nozzle and ejector system is not necessary.
In this thesis, design of a connected pipe test facility is implemented. Three main systems are analyzed / air storage system, air heater system and test stand.
Design of air storage system includes the design of pressure vessel and pressure & / flow regulation system. Pressure and flow regulation system is needed to obtain the actual flow properties that the combustor is exposed to during missile flight. Alternatives for pressure and air mass flow rate regulation are considered in this study. Air storage system designed in this thesis is 27.8 m3 at 50 bar which allows a test duration of 200 seconds at an average mass flow rate of 3 kg/s.
Air heater system is utilized to heat the air to simulate the aerodynamic heating of the inlet. Several different combustion chamber configurations with different flame holding mechanisms are studied. The most efficient configuration is selected for this study. Combustion analysis of the air heater is performed by FLUENT CFD Code. Combustion process and air heater designs are validated using experimental data. Designed air heater system is capable of supplying air at a temperature range of 400-1000 K and mass flow rate range of 1.5-8 kg/s at Mach numbers between 0.1-0.5 and pressure between 2-8 bar.
Finally the design of the test stand and ramjet combustor analysis are completed. 3D CAD models of the test stand are generated. Ramjet combustor that will be tested in the test setup is modeled and combustion analysis is performed by FLUENT CFD Code. The ramjet engine cruise altitude is 16 km and cruise Mach number is 3.5.
Key-words: Air Breathing Engines, Ramjet, Connected Pipe, Direct Connect, Vitiator.
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Design Of A Computer Interface For Automatic Finite Element Analysis Of An Excavator BoomYener, Mehmet 01 May 2005 (has links) (PDF)
The aim of this study is to design a computer interface, which links the user to commercial Finite Element Analysis (FEA) program, MSC.Marc-Mentat to make automatic FE analysis of an excavator boom by using DELPHI as platform. Parametrization of boom geometry is done to add some flexibility to interface called OPTIBOOM. Parametric FE analysis of a boom shortens the design stages and helps to find the optimum design in terms of stresses and mass.
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Optimum Design Of Multistep Spur GearboxOzturk, Fatih Mehmet 01 December 2005 (has links) (PDF)
Optimum design of multistep gearbox, since many high-performance power
transmission applications (e.g., automotive, space industry) require compact volume,
has become an important interest area. This design application includes more
complicated problems that are not taken into account while designing single stage
gear drives. Design applications are generally made by trial and error methods
depending on the experience and the intuition of the designer.
In this study, using Visual Basic 6.0, an interactive program is developed for
designing multistep involute standard and nonstandard spur gearbox according to the
American Gear Manufacturers Association (AGMA) Standards 218.01 and 2001-
B88. All the equations for calculating the pitting resistance geometry factor I, and
the bending strength geometry factor J, are valid for external spur gears that are
generated by rack-type tools (rack cutters or hobs). The program is made for twostage
to six-stage gear drives, which are commonly used in the industry.
Compactness of gear pairs and gearbox, and equality of factor of safety against
bending failure is taken as the design objective. By considering the total required
gear ratio, the number of reduction stages is input by the user. Gear ratios of every
stage is distributed to the stages according to the total gear ratio that satisfies the
required precision (from ± / 0.1 to ± / 0.00001 on overall gear ratio) depending on the
user selected constraints (unequal gear ratio for every stage, noninteger gear ratio
e.g.). Dimensional design is determined by considering bending stress, pitting stress,
and involute interference constraints. These steps are carried out iteratively until a
desirable solution is acquired. The necessary parameters for configuration design
such as number of teeth, module, addendum modification coefficient, are selected
from previously determined gear pairs that satisfies the constraints by user
interaction considering the performance criterion from the developed program. The
positions of gears and shafts are determined automatically in order to keep the
volume of gearbox as minimum while satisfying the nonlinear spatial constraints
(center distance constraint for proper meshing of gear pairs, face distance constraint
for proper assembly of pinion and gear having same shaft, gear interference
constraint for preventing interferences between gears, shaft interference constraint
for preventing interferences between gears and shafts) by using DLL (Dynamic Link
Library) technology of Lingo 8.0 optimization software together with Visual Basic
6.0. If shaft interference constraint is removed then cantilevered mounting of gear
pairs would also be possible, otherwise the gears should be mounted between
bearings. Visual output of assembly is made by using Autodesk Inventor 7.0,
automatically by the program.
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Thermo-mechanical Finite Element Analysis And Design Of Tail Section For A Ballistic MissleGuler, Togan Kemal 01 October 2012 (has links) (PDF)
During the flight of missiles, depending on the flight conditions, rotation of missiles around its centerline can cause instabilities. To override this issue, missile generally is designed in 2 sections. In the missile, the rear tail section and the front section are to rotate freely by means of bearings. Tail section on which bearings are mounted is designed according to thermal loads due to flow of hot gasses through the nozzle and mechanical loads due to inertial load, interference fit and thread preload which appear during flight of missile.
The purpose of this thesis is to determine the most suitable structural parameters according to the flight conditions of missile.
The geometrical and load parameters which have effect on the results were determined. Finite element model is formed by using FEA software. After that, transient nonlinear thermo-mechanical analyses are performed and the most effective parameter on VM (Von-Mises) stress and force is determined.
DOE (Design of Experiments) method was used to determine the most suitable values for the structural parameters. Totally 27 different configurations are studied to achieve to the most suitable values for variable set.
It is observed that VM stress and force results for all configurations are within the ± / %5 ranges. So this means parameters don&rsquo / t affect the systems response very much. By taking manufacturing processes into consideration, configuration with the highest bearing inner/outer ring interference is taken. From the comparison of the results, the most suitable configuration is obtained after checking forces and VM stress on the bearings.
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Design And Production Of A Dissimilar Channel Angular Pressing System To Obtain High Strength Aluminum Alloy SheetsUzuncakmak, Gokturk Emre 01 June 2009 (has links) (PDF)
The aim of this thesis work is to design and manufacture a Dissimilar Channel Angular Pressing (DCAP) system for severe plastic deformation of aluminum alloy sheets in order to obtain ultra-fine grained structure. First, a DCAP system was designed by Finite Element Analysis and constructed after various optimization trials. Next, 6061-T0 aluminum alloy plates were severely deformed by various DCAP passes through the system. The samples were characterized by metallography, X-ray diffraction, tension and hardness tests. It has been observed that the yield strength was improved about 100 % after 2 DCAP passes, and 45 nm sub-grain size was obtained.
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