Novel Rail Stress Measurement Technique Using Piezospectroscopy

Photoluminescence piezospectroscopy (PLPS) technique is a laser-based non-contact non-destructive technique to measure the stress in Al2O3 (alumina). By irradiating laser onto the surface of alumina, the stress level can be calculated. Thermite welding is one of the most popular welding technique in rail installation. The reaction produces iron and alumina between the ends of two rails. In this study, a feasibility study has been performed to use the alumina in thermite welds as a stress sensor using PLPS technique. A rail specimen, that was in service condition, has been prepared to experimentally validate the feasibility. The microstructure is first investigated using SEM and EDX. Then, uniaxial compression tests have been performed to small pieces of the thermite weld specimen to investigate the piezospectroscopic effect of alumina in thermite rail. The experimental results show that the novel rail stress measurement technique using PLPS has a high possibility to measure the stress in rail without any sensor installation and contact