Study on Train Wheel Out-of-Roundness Monitoring Method by PVDF Sensing Technology

Wheel out-of-roundness (OOR) inevitably jeopardizes the safety of railway operations. Regular visual inspection and checking by experienced workers are the commonly adopted practices to identify wheel defects. However, the defects may not be spotted in time. The paper puts forward a new method to real-time monitor wheel OOR based on PVDF strain sensor. Track strain response upon wheel-rail interaction is measured and processed to generate a condition index which directly reflects the wheel condition. Firstly, theoretical model of relationship between PVDF sensor output and wheel/rail loads is set up, and principle for measuring vertical wheel/rail contact forces is proposed. Secondly, the effects of horizontal wheel/rail force and train speed on the output results are discussed. Finally, this approach is verified by finite element analysis, and the preliminary results show that this electromagnetic-immune system provides an effective alternative for wheel defects detection.