Modelling thermal effects in ratcheting-led wear and rolling contact fatigue

Railway rails accumulate severe plastic deformation at the surface as a result of loading by passing wheels. This process of plastic strain accumulation is plastic ratcheting. Ratcheting failure occurs when material accumulates a critical strain and failed material produces wear debris and rolling contact fatigue cracks. A computer model of strain accumulation, ratcheting failure and wear has been developed which can be used to simulate and predict wear and crack initiation in rails. The current work incorporates thermal stress and material softening due to frictional heating in the contact area into the computer simulation. The effects of friction coefficient and slip/roll ratio on the wear rate and rolling contact fatigue are investigated, and frictional heating effects have been found to increase the rate of damage accumulation by ratcheting, leading to increased wear and tendency for rolling contact fatigue

Remote Pressure Water Valve Control System Based on PLC

Currently, valve operations use manual processes to safeguard water pressure and distribution to the Regional Water Company. Conventional systems are still used upon operations in opening and closing the valve. This method requires operators to rotate the valve by hand to maintain the distribution and water pressure's stability to the Regional Water Company. It would be more efficient if operators can maintain the distribution and water pressure stability without going to the location where the valve is located. A PLC and Android-based distribution valve remote control system design is planned to be produced from this research. Control commands are done via HMI display on Android to the PLC via PC and server to control the gearbox motor located on the valve. The pressure analysis shows that there are differences before the control system is installed. The pressure tends to be under 4 bar and is less stable. However, after the control system is installed, it tends to be more stable, between 4 bar and 4.5 bar. The data flow results show a difference in the flow before the control system is installed. The distributed flow tends to be below the number 180 l / s and is less stable. After installing the control system, the flow is more stable and increased from originally at an average of 144.4 l/s to 171.2 l/s, a difference of 26.8 l/s.