Impact Damage to Joint Components Caused by Rail End Crushing
Q1: Why does rail end crushing aggravate joint impact?
A1: End crushing causes local subsidence and steps at the rail end, generating strong instantaneous impact when wheels pass. Impact energy is transmitted to fishplates, bolts, pads and other components, greatly increasing their dynamic load and significantly accelerating the speed of fatigue damage.
Q2: Why are joint bolts in crushed sections more prone to fatigue fracture?
A2: Impact causes bolts to bear repeated combined tension and bending stress, with stress amplitude far exceeding that of normal sections. Rail end jumping makes joints open and close frequently, bolts continuously bear dynamic tension, cracks propagate rapidly, and fatigue fracture is extremely easy to occur at the root or thread section.
Q3: What impact does end crushing have on the service life of fishplates?
A3: Impact sharply increases the bending moment in the middle of fishplates, causing plastic bending and arching deformation. Cracks quickly initiate at stress concentration parts, especially through cracks near bolt holes. The more severe the crushing, the shorter the replacement cycle of fishplates.
Q4: What harm does rail end fat edge do to clips and gauge retention?
A4: Fat edge invades the gauge range, forcing rails to offset outward and widening the gauge. At the same time, clips bear eccentric stress, clamping force decreases, and line lateral resistance is insufficient. Fat edge also aggravates wheel-rail wear, forming a situation where rail ends and components are damaged simultaneously.
Q5: How to reduce rail end crushing and component damage through operation and maintenance measures?
A5: Timely grind rail end fat edge and crushed parts to restore standard end face. Retighten joint bolts to improve joint stiffness. Replace crushed and failed pads to improve support conditions. Strengthen joint inspection, and timely replace severely crushed rails to avoid disease expansion.