دانلود کتاب Determination of Longitudinal Stress in Rails

The objective of this Innovations Deserving Exploratory Analysis (IDEA) project was to determine the longitudinal stress in rails, in order to reduce rail buckling due to temperature-induced stresses. Continuous welded rails (CWR) are typically long members which are susceptible to failure caused by temperature changes. Such rail temperature changes can cause considerable disruption to the rail network and, in the worst case, cause freight or passenger train derailment. An important parameter in analysis of temperature induced stresses is the rail neutral temperature (RNT), defined as that rail temperature at which the net longitudinal force in the rail is zero. The objective of this project was to determine the longitudinal stress in rails using the polarization of Rayleigh surface waves, to reduce buckling and fracture. This project developed a non-destructive procedure for monitoring the stress-free temperature in rails using the acoustoelastic effect of ultrasonic waves. Acoustoelasticity is the stress dependency of ultrasonic wave speed or polarization. Analytical models were developed to explain the relationship between the polarization of Rayleigh waves and the state of stress. Rayleigh waves were detected using a laser Doppler vibrometer (LDV). Furthermore, the polarization of Rayleigh waves is considered as a measure to identify applied stress.