Failure Analysis of the Headspan Suspension in the Railway Power Supply System

Premature failure of headspan suspensions was mainly attributed to the fracture failure of the droppers. Various experiments were conducted to explore the fracture failure mechanism of the droppers used in headspan suspensions. Four notches along the axial direction of the dropper, corrosion pits and corrosion products were observed by visual examination. Although the axial cracks have little effect on the structural strength, they make it easier to form corrosion environment in the notches than on the exposed outer surfaces. Furthermore, energy spectrum analysis indicated the presence of chlorine and sulfur both in the corrosion products inside of axial cracks and corrosion pits. Meanwhile, typical microstructural features of intergranular cracking and corrosion products were observed by the scanning electron microscopy. Finally, finite element analysis was conducted to characterize the stress distribution near the corrosion pits. The simulation results showed that obvious stress concentration was formed near the corrosion area. All the results indicated that the droppers failed due to the combination of pitting corrosion and stress corrosion cracking.