STRUCTURAL HEALTH MONITORING AND ENERGY HARVESTING FOR RAILROAD

Abstract

Abstract: Untimely damage detection/heath monitoring of rails and improper functioning of the trackside infrastructure like signals, gates, switches etc results in service disruptions, inefficient transportation management, or severe train accidents and cause huge direct and indirect losses. To facilitate policy makers and rail transportation agencies to make informed decisions on operating and managing the region's transportation system implementing continuous health monitoring methods for rails and self powering the railway track side electric infrastructure is essential. In this thesis continuous structural health monitoring methods for rail is developed. The train(actuator) induced elastic waves are used for long range damage detection and piezoelectric admittance based methods are used for localized damage detection. Train induced high frequency elastic waves are analyzed by taking the wheel-rail interaction as the moving Hertzian contact forces using the semi-analytical finite element analysis. Their feasibility for long range damage detection is explained by calculating their decay rate. Low cost piezoelectric admittance based method using higher order inductive circuits is analyzed. The circuit parameters are optimized to enhance admittance damage metric sensitivity for localized damage detection. Energy harvested from the railway track vibrations due to the moving trains can be used to self power the railway track side electric infrastructure. In this thesis the available power in the track site is estimated. Conventional Linear electromagnetic energy harvesters are assessed for energy harvesting from the erratic railway track vibrations and improvements to the linear harvester design to achieve high power density are discussed. A novel high efficient and reliable rotational energy harvester suitable for the irregular track vibration energy harvesting is proposed. The harvester designed has mechanical motion rectifier to convert the irregular up-and-down vibration into regular unidirectional rotation and a flywheel to stabilize the generator speed. A full-scale prototype of this novel energy harvester was built and preliminarily tested in lab. The power harvested is sufficient enough for powering the track side electric infrastructure like signal lights, track switches etc as well as the structural health monitoring systems.