Integrity evaluation of cracked railway bogie frame

초록

A procedure to calculate stress intensity factor, SIF by using the stress transient at crack tip was proposed by incorporating sub-modeling method. For this purpose, a virtual crack was modeled in the critical point of railway bogie frame based on the results from non destructive inspection on aged railway vehicles. Dynamic strains at the crack tip were measured during train running in commercial line and they were converted into dynamic stress. Total stress was calculated by summing the dynamic stress and static stress from vehicle and passenger weight. The stress field was used as loading condition in the sub-model and finally the SIF could be calculated. Crack growth analysis was performed by applying linear elastic fracture mechanics. The effective stress intensity factors were calculated using the measured strain history at a crack tip and crack growth was simulated. We can calculate a period from crack detection to critical crack length to failure.