Failure case analysis of fastening bolts for trolley rail of quay crane

Abstract

This paper presents a premature failure analysis of bolts used for trolley rail fastening system of quay crane. The investigation included experimental and numerical analysis. Failure bolt inspection revealed the failure site was at the combination of thread run out and under-head-to-shank transition. Failure bolt chemical composition analysis shows no material and manufacturing defect. Fracture surfaces morphology of the failure bolts reveals premature fatigue fracture process. Structural health monitoring (SHM) and field test indicated the main failure cause are high strength impact due to trolley passing through rail gap because of worn rail pad and unreasonable design of rail clip. Numerical simulations have been conducted. The installation simulation of rail fastening system shows eccentricity loading condition of bolt due to incline of rail clip. Combined with field test of rail gap region vertical acceleration, the trolley rail system has been simulated via finite element analysis to illustrate the mechanism of bolt failure. Worn rail pad at rail gap region produced high level of impact load due to trolley passage. The influence of worn level of rail pad on bolt stress has been investigated. A modified design of rail clip is presented. The comparison of the original and modified rail fastening system as well as the elastic and rigid rail fastening system had been conducted.