Investigation on wear and friction of carbon strips by developed testing system for railway systems

Light rail systems are widely used to solve the traffic and transportation problems in today's cities. In addition to being suitable for comfortable public transportation, the technical features such as being sensitive to the environment and high energy efficiency are effective in the preference of HRS. The pantograph-catenary system plays an active role in the transmission of electrical energy to the power transmission system of the HRS. In this doctoral thesis, a programmable and measuring experimental setup that simulates the sliding frictional disturbance movement between the current collector graphite plate and the catenary contact wire, which is one of the pantograph mechanism elements, has been designed and manufactured. In the experimental setup, the contact force and friction force change trends were examined during the interaction of the graphite plate and the contact wire, and then these parameters were analyzed with the Taguchi Method and ANOVA statistical program. In addition, in the experimental setup, the stop information of the Samsun province OMU Yurtlar-Tekkeköy HRS route line was simulated with the control analysis software, thus the mechanical friction and wear behaviors of the graphite plates were investigated in a realistic way. As a result of the experiments carried out in dry and wet conditions, friction and wear data were obtained depending on the contact force, speed and distance, and the surface images of the worn graphite plates were analyzed and interpreted. As a result of the experiments, a synchronous tribological experiment setup, which can realistically simulate the train movement in the field of rail systems, has been brought to the literature. As a result of the experimental studies, it was determined that the contact force, distance and speed parameters used during the friction and wear tests do not affect the friction coefficient as long as the wear environment does not change. The friction coefficient was measured as 0,75, the operating temperature was 55 ºC, and the mass loss of the graphite plate as a result of wear was 0,72 g in the wear tests carried out under the 50-55 N contact force in dry condition along the OMU Yurtlar-Tekkeköy HRS route line in Samsun. As a result of the experiment performed in wet condition with the same route information, the friction coefficient was measured as 0,65, the operating temperature was 32 ºC, and the mass loss of the graphite plate as a result of wear was 0,98 g. As a result of SEM and AFM analyzes performed on the surfaces of the worn graphite plates, it was determined that the surface became smoother in dry condition (R_a 28.34 nm), abrasive and adhesive wear mechanisms were effective, material transfer from the copper contact wire and plastic deformation damages occurred on the surfaces. In the results of the wet environment, it was observed that the surface had a roughness value (R_a 55.35 nm) close to its original state and no material transfer was observed. More surface damage was observed compared to the dry environment condition.