Numerical Simulation Research On The Influence Of Welded Joints On The Operation Safety Of High-Speed Trains

Due to the difference between the welding material and the base metal,the welding process and the influence of human factors,even though the seamless track technology has become mature now,there are still rail surface irregularities represented by welding joint defects.Although this unevenness is smaller than the shock and vibration produced by the traditional railway track line joint,it gradually deteriorates the welding joint defects over time,and then generates greater impact,forming a vicious circle,and finally causing a series of track damage Problems threaten the safety of train operation.Therefore,damage and wheelrail matching response near welded joints are threats and problems faced to the world.This article first briefly reviewed the research status and progress in the field of rail welded joints at home and abroad,and then established a wheel-rail rigid-flexible coupling model based on the theory of vehicle-track coupling dynamics.Aiming at the rail welded joints dominated by harmonic irregularities,this article compares the high-speed trains passing through welded joints with wave depths of ±0.1mm,±0.2mm,and ±0.3mm at speeds of250km/h and 350km/h,respectively.The wheel-rail dynamic response is analyzed in detail,and the safety parameters are mainly based on the wheel-rail vertical force,derailment coefficient and wheel load reduction rate.The simulation calculation shows that the maximum wheel-rail force peak under the excitation of the concave joint irregularity is greatly affected by the short-wave part of the joint irregularity,and the maximum wheel load reduction rate is larger;the convex joint irregularity excitation will cause a larger Peak wheel/rail force response.At the same time,due to certain limitations when using the derailment coefficient as the evaluation index,it is more reasonable to use the wheel load shedding rate as the evaluation index.Finally,it is concluded that for concave welded joints,when the vehicle’s forward speed is 250km/h,the irregularity wave depth of the orbital welded joint should be controlled below 0.24mm;when the vehicle’s forward speed is 350km/h,the irregularity of the orbital welded joint should be controlled below 0.18 mm.For convex welded joints,when the vehicle’s forward speed is 250km/h,the irregularity wave depth of the orbital welded joint should be controlled below 0.18mm;when the vehicle’s forward speed is 350km/h,the irregularity wave depth of the orbital welded joint should be controlled below 0.16 mm.