The focus of this study is to find fatigue behavior and fatigue life of a drag link in the different road and loading conditions. Finite element method was used for fatigue analysis and fatigue life of the drag link was predicted. Firstly, the historical changes in the concept of the fatigue and fatigue life calculation methods were explained in the chapter one and two. Factor affecting the fatigue performance was explained. Stress and strain based fatigue analysis methods were described clearly. Finally, fatigue life analysis in the frequency domain which is a new method relative to the others was explained. Then, two different steering drag links of a midibus were examined and fatigue life calculations of these two drag links were made. The fatigue life analysis in the time domain of the drag links were made in the static steering conditions and the results were compared with the test results made by the vendor of the drag links. After that, the drag link which has a greater fatigue life than the other was selected, the road loads were taken from another test report which was made by using the same drag link and the fatigue life of the drag link was computed by using the finite element method in the time domain. Finally, the same road loads were converted in the frequency domain and the fatigue life analysis of the same drag link were made in the frequency domain. The results from the time domain and the frequency domain were compared and the advantages of the fatigue life analysis in the frequency domain were expressed.

High velocity impact and penetration problems include large deformation, erosion, high strain rate dependent nonlinear material behavior and fragmentation. Therefore, meshless methods seem to be ideally suited for the modeling of penetration events as they allow unrestricted deformation and easy tracking of material interfaces and loading histories. In the first part of this study, a brief overview about meshless methods is given. Also the most important features of meshless methods with respect to mesh based approaches are compared. In the second part, numerical model is developed using one of the most frequently used meshless method, Smoothed Particle Hydrodynamics (SPH). 3D numerical simulations are performed on a high performance computer using MPP version of the explicit finite element code LS-Dyna. For reasonable behavior of material response under dynamic loading, Johnson Cook material models for armor steel target and 7,62 armor piercing projectile are derived using SHPB (Split Hopkinson Pressure Bar) test data. SPH computational investigation is compared with available experimental data such as penetration depth and impact crater diameter. For the future work, other potential meshless methods for ballistic impact problems are identified.

Nowadays robots are used in various areas. There are extremely important applications where the robot arm tip comes in contact with the environment or an object. During controlling an object, static or in motion, the object or the robot arm should not be damaged. The interaction forces are important in such conditions. Whether the task succeeds or fails depends on how accurate the interaction forces are controlled. The interaction forces are changed depending on the motion of the robot arm. Therefore, to control interaction forces a force control algorithm must be developed. In this research a force control algorithm will first be developed for the quasi-static contact tasks, then it will be extended to the dynamic cases. The goal of this study is to compare force control strategies to achieve the desired interaction forces between the robot arm tip (end-effector) and the environment during contact tasks. Taguchi L9 method is used for comparison of selected force control algorithms which are modeled in SIMULINK MATLAB program.

Manufacturing companies need to improve their production technology with improved dimensional accuracy at lower cost in order to manufacture sheet metal based products. Scrap shedding is an issue that should be examined at the cutting and sheet metal forming operations. In order to extend the life cycle of the cutting moulds, scrap shedding should be identified. When scrap shedding has not been taken into consideration, scraps have accumulated in the moulds reducing the production quality and causing deformation of the mould, increasing the production cost by obligating to perform extra transactions. This study becomes more focused upon the analysis of scrap shedding. In order to simulate the scrap shedding LS-Dyna and Pam Stamp software have been used. For examining of the scrap shedding an automotive part was chosen. In order to realize scrap shedding having any problems, new improvements have been suggested. Design of Experiments techniques which provide important advantages to engineering studies have been examined. By means of experimental design techniques the scrap shedding design process was also added to the classical mold design approach via a less quantities of simulations.