重载铁路桥墩高强度螺栓延迟断裂的有限元分析

Finite Element Analysis of Delayed Fracture of High Strength Bolts in Bridge Piers of Heavy Haul Railway

随着重载铁路列车轴重和载运量的增加,桥墩承受的压力越来越大,采取有效措施提升桥墩螺栓的强度势在必行,其中延迟断裂现象是提升螺栓强度的主要因素。针对重载铁路桥墩高强度螺栓延迟断裂问题,选择合适的研究样本并设置相应参数建立有限元模型,计算螺纹根部主应力数值,分析在不同直径、不同螺纹形状、不同外露螺纹数量以及不同牙底圆角半径情况下的螺栓缺口应力集中效应,提出高强度螺栓在螺纹缺口处的应力集中效应使其应力峰值降到最低,能够有效缓解结构应力疲劳,达到改善延迟断裂的目的,从而缓解重载铁路桥墩承受压力,提高重载铁路运行安全系数。

With the increase in the axle load&load capacity of heavy-duty railway trains,the pressure on the bridge piers is increasing.It is imperative to take effective measures to improve the strength of the pier bolts.Delayed fracture is the main factor in improving the strength of the bolts.Aiming at the delayed fracture problem of high-strength bolts of heavy-duty railway piers,select appropriate research samples and set corresponding parameters to establish a finite element model,calculate the principal stress value at the root of the thread,and the stress concentration effect of the bolt notch is analyzed under different diameters,different thread shapes,different numbers of exposed threads,and different bottom fillet radii.It is proposed that the stress concentration effect of high-strength bolt at the thread notch can reduce the peak stress to the minimum,which can effectively alleviate the structural stress fatigue and achieve the purpose of improving the delayed fracture,so as to relieve the pressure on the pier of heavy haul railway and improve the safety factor of heavy haul railway operation.