Research on Stress Distribution Characteristics in the Wheel-Seat Zone of railway wheelset

Abstract

The wheel-seat zone is a high-risk area for fretting fatigue and wheel-axle loosening failure. During service, it simultaneously bears multi-field coupling effects including mechanical loads, rotational centrifugal force, emergency braking thermal loads, and track impact loads. The dynamic fluctuation of contact stress directly determines the operational safety of the running gear. Taking the EA4T hollow power axle as the research object, this paper adopts a fully coupled thermal-mechanical algorithm to carry out independent single-field simulations and multi-field superimposed combined-condition simulations respectively: 1) Simulate the entire emergency braking process at 200/300/400/500 km/h and the wheel-axle temperature conduction and contact stress transfer laws during the parking cooling stage; 2) Quantify the weakening effect of centrifugal force at different rotational speeds from 200 to 500 km/h on the interference fit interface stress, and analyze the disturbance of track defect impact on the contact field combined with line-measured impact load spectra; 3) According to four typical coupled conditions—static load, high-speed centrifugal load, single emergency braking, and multiple consecutive braking—systematically reveal the axial and circumferential stress and micro-slip distribution characteristics in the wheel-seat zone under multi-physical field superposition. The results show that the wheel-seat stress exhibits a "high at both ends, low in the middle" distribution along the axial direction, with significant stress gradients at the contact edges. Both centrifugal force and braking temperature rise reduce the average interface contact stress, with the thermal accumulation of consecutive braking having the most significant weakening effect. Impact loads only locally amplify the edge stress peaks without altering the overall distribution pattern. Under the four coupled conditions, the fatigue strength of the wheel-seat zone meets UIC standards, but the fatigue safety margin at the inner edge is relatively low. This research can provide simulation-based references for the selection of interference fit amounts in EMU wheel-axle press-fitting, operational control of braking conditions, and axle fatigue life extension.