Turning and milling are the main manufacturing techniques in industry. A great deal of time and money is spent for machining operations. Although most of the time, the tool path of a CNC machine tool is generated by a Computer Aided Manufacturing (CAM) software package, to be sure that the result of the machining operation will be as required, it is necessary to use a simulation software. There are various machining simulation software packages available in the market. However, they are not only expensive, but also specialized for only one of the before mentioned machining techniques. Most of the companies in the industry are small or medium scale ones and, it is not so easy for them to afford a specialized simulation software for that purpose. In this thesis, it is aimed to develop a software package, which will be used to simulate advanced industrial machining processes, including turning and milling. Dexelmodeling, which is generated by ray casting, and sweep plane algorithm withpolygon clipping technique are used forvisualization. For polygon clipping technique, outer surfaces of the resultant workpiece are generated from planar contours. The software is developed in C# programming language and DirectX libraries are utilizedfor visualization purposes. With the aid of this software, it is also aimed to visually confirm the validity of both mill and lathe NC-code, by representing highly accurate 3D displayed results of these simulations.

This study focuses on kinematic calibration of industrial robots. Kinematic modeling, parameter identification and optimal pose selection methods are presented. A computer simulation of the kinematic calibration is performed using generated measurements with normally distributed noise. Furthermore, kinematic calibration experiments are performed on an ABB IRB 6600 industrial robot using full pose measurements taken by a laser tracking system. The kinematic model of the robot is developed using the modified Denavit - Hartenberg convention. A nonlinear least-squares method is employed during the parameter identification stage. According to the experiment results, the initial robot positioning errors are reduced by more than 80%.

Radar antenna structures especially array antennas which are integrated onto structures of aerial vehicles are subject to dynamic structural and aerodynamic loads. Due to occurrences of these dynamic loads there will be certain dynamic deformations which affect the antenna&rsquo / s performance in an adverse manner. The influence of deformations and vibrations are important on array antenna structures, since they cause a change in orientation of elements of the phased array antenna which affects the gain of the antenna negatively. In this study, vibration characteristics of a particular radar antenna structure are optimized using topology and stiffener design optimization methods such that negative effects of mechanical vibrations on functional performance of radar antenna are minimized. Topology and stiffener design optimization techniques are performed separately by the use of ANSYS Finite Element (FE) software in order to modify the design of the radar antenna structure such that its critical natural frequencies in the range of 0-500 Hz are shifted out of the dominant peak sinusoid frequency range of the air platform. As a result of this, it will be possible to minimize the vibration response of the phased array elements in the frequency range of 0-500 Hz / hence better antenna performance can be achieved. In addition to this, it will also be possible to minimize the broadband random vibration response of base excitation coming from air platform.

The rapid advancement of information technology and its integration with the manufacturing technology increased the necessity of consistent and coherent data flow in the chain of Computer Aided Design (CAD)-Computer aided Manufacturing (CAM)-Computer Numerical Control (CNC). To achieve this, ISO 10303 standard (STEP), developed by ISO, is seen as a solution since STEP is independent of the environment on which design data, manufacturing data or machining data produced. In this thesis, efficiency of NC-code generation, with the inclusion of process planning data, from a STEP based CAD data is investigated. For the investigation purposes, software responsible for both building the STEP based CAD data and generating related NC-code automatically is developed. Using this software, several parts are designed / generated NC-codes are verified via CNC simulators and some test parts are produced. STEP AP224 based feature modeler, developed specifically for 2- axis rotational part design, includes / feature library, feature modeler employing SW2007 via API for visualization and preprocessor responsible for generation of STEP file in neutral format, called STEP Part 21. The NC-code generator includes / postprocessor responsible for STEP Part 21 interpretation, CNC machine tool and cutting tool database and preprocessor responsible for NC-code generation.

Tonpilz-type transducers are the most commonly used projectors in underwater acoustic applications. However, no complete design approach is available in the literature for such transducers. The present study aims to fill this gap in the literature by providing a systematic design approach for the Tonpilz-type transducers. The proposed methodology involves the use of different analytical models and a finite element model of such transducers. Each model provides a different level of accuracy that is tightly correlated with the models complexity and computational cost. By using these models sequentially starting with the simplest and fastest model to yield an initial design and concluding with the most detailed and accurate model to yield an optimized final design the overall design time is reduced and greater flexibility is given to the designer. An overview of each of these four models is given. The constructed models are benchmarked against published experimental data. The overall design methodology is demonstrated by systematically applying the four models to design a Tonpilz-type transducer. Possible improvements to the proposed methodology are discussed.

In this thesis, a Thermal Model Tool (TMT) is developed for standard Avionic Transport Rack (ATR) chassis and thermal design of a standard ATR chassis is done using developed TMT. This ATR chassis is a Digital Moving Map (DMAP) of a helicopter and the tool is used to determine the cooling channel details of DMAP. TMT decreases design process steps and eliminates the complexity of the design. Experimental studies are conducted on one of the existing chassis produced in Aselsan Inc. for different operating conditions. There are two different operating conditions for the chassis as 25 &ordm / C and 55 &ordm / C, which are given, in military standard MIL-STD-810F. Critical temperature values are measured, which are used in analytical calculations, and results are represented. At the first step, outputs of the experimental studies are used in analytical calculation in order to develop TMT. Secondly, heat dissipation rate of two different chassis are v calculated easily by using the TMT, and without making effort for CFD analysis, the necessary number of plate fins of the chassis are assessed considering given geometrical constraints and heat loads. Finally, cooling channels are generated using the results of TMT. In the next step the chassis, which are designed using the results of TMT, are analyzed numerically by using Icepak Computational Fluid Dynamics (CFD) tool and results of TMT are verified. The cooling capacities of the decided plate fins, which are obtained by TMT, are checked whether or not the required heat dissipation rates are ensured. Consequently, TMT is tested under for two different operating conditions on two different chassis. Analytical and numerical studies for both conditions are compared and discussed in detail. Comparisons show that, developed TMT results are meaningful and close to numerical results, therefore TMT can be used in forthcoming ATR chassis designs.

Ballistic testing is a vital part of the armor design. However, it is impossible to test every condition and it is necessary to limit the number of tests to cut huge costs. With the intro- duction of hydrocodes and high performance computers / there is an increasing interest on simulation studies to cutoff these aforementioned costs. This study deals with the numerical modeling of ballistic impact phenomena, regarding the ballistic penetration of hardened steel plates by 7.62 mm AP (Armor Piercing) projectile. Penetration processes of AP projectiles are reviewed. Then, a survey on analytical models is given. After the introduction of fun- damentals of numerical analysis, an intensive numerical study is conducted in 2D and 3D. Johnson Cook strength models for the four different heat treatments of AISI 4340 steel were constructed based on the dynamic material data taken from the literature. It was found that 2D numerical simulations gave plausible results in terms of residual projectile velocities, con- sidering the literature review. Then, 3D numerical simulations were performed based on the material properties that were selected in 2D studies. Good agreement was obtained between the numerical and test results in terms of residual projectile velocities and ballistic limit thick- nesses. It was seen that the ballistic protection efficiency of the armor plates increases with the increasing hardness, in the examined range. This study is a part of T&uml / ubitak project 106M211 of MAG.

Stirling cycle cryocoolers are used widely in military applications. The regenerator is the key element of Stirling cycle cryocoolers. It is known that performance of the regenerator directly affects the cryocooler performance. Therefore, any improvement on the regenerator will lead to a more efficient cryocooler. Thus, it is essential to have an idea about regenerator parameters and their effects on the system. In this study Stirling engine regenerator, which is constructed by wire mesh screens, is accepted as a porous medium. Using energy balance and continuity equation, matrix and fluid thermal equations are derived. Simplified versions of these equations are obtained for not only the ideal case, but also two other cases which take into account the effects of longitudinal conduction and the effects of regenerator wall. A computer code is developed in Matlab to solve these equations using finite difference method. The developed code is validated by using Sage. Afterwards, effects of all regenerator parameters on regenerator performance are investigated in detail and results are presented. To make this investigation easier, a graphical user interface is also built (in Matlab) and used.

During the design and development stages of mechanical structures, after each modification made in order to satisfy design criteria, dynamic characteristics of the structure change and should be determined through reanalyzing the structure dynamically. Due to the significance of computational time and cost in design processes, it is inevitable for structural modification methods, especially for large systems, to become involved in predicting the dynamic behavior of modified structures from those of the original and modifying structures. Since most engineering structures are inherently nonlinear, linear approach may not be valid no more. Therefore, conventional structural modification methods can not be directly used, instead a nonlinear structural modification method needs to be employed. In this thesis, it is aimed to adapt an effective linear structural modification method to structures with nonlinear modification or coupling. The amplitude dependencies of nonlinearities are modeled by using describing function method. Mathematical formulations are embedded in a computer program developed in MATLAB&reg / with a graphical user interface. The software uses modal analysis results of ANSYS&reg / for the original structure and dynamic stiffness matrix and nonlinearity information that belong to the modifying structure in order to calculate dynamic response of the modified structure. The approach is verified by applying it to both discrete and real test structures previously studied in literature and generated discrete structures, then comparing the results with prior ones and ones obtained via time domain integration, respectively. Several other case studies are also included in order to demonstrate the applicability and to investigate the performance of the method. It is concluded in this study that the structural modification method proposed can be successfully and efficiently used for structures with nonlinear modification or coupling.

Impact of rain drops at relatively high velocities, which is known as rain erosion, causes severe damages on various materials. Every material can withstand the rain erosion up to a specific impact velocity. However, this damage is critical for optical windows which are very important components for Electro-Optical (EO) systems such as thermal camera. Even a small scratch may affect the transmission capability of the optical window adversely and leads to some functional problems in the device due to insufficient transmitted data. Since it has a vital effect on the EO systems, the rain erosion is needed to be investigated on the special optical windows, particularly for determining the velocity that a damage initiates. In this study, the rain erosion is investigated on germanium which is a kind of optical window, by means of numerical simulations in LS-DYNA. Damage Threshold Velocity (DTV) is examined for two different water shapes (which are spherical water drop and water jet) within a velocity range between 100 and 250 m/s. Both single and multiple impact cases are considered for both water shapes up to ten consecutive collisions. By using the results, the &ldquo / DTV versus number of impact curves&rdquo / are obtained in order to understand the amount of damage with respect to both single and multiple impacts. Results are compared with both literature and the experimental data within the scope of DTV and shape of the damage. In the numerical simulations, ALE (Arbitrary Lagrangian Eulerian) method is used for modelling water. &ldquo / JOHNSON-HOLMQUIST-CERAMICS (JH-2)&rdquo / which is recommended for both ceramics and glass applications is used as the material model for Germanium. JH-2 is a complete material model which contains damage effects, failure criteria, and Equation of State (EOS) all together. Among the material models available in the library of LS-DYNA, &ldquo / MAT-NULL + EOS-GRUNEISEN&rdquo / is used for water.