【作者】 王振；

【导师】 蔡振兵；

【作者基本信息】 西南交通大学 ， 机械设计及理论， 2013， 硕士

【摘要】 扣件是连接钢轨和轨枕使之形成轨排的部件,对保证轨道稳定性、可靠性起到重要作用,对铁路运输的安全起着重要影响。Ⅲ型扣件是一种为高速重载铁路设计的新型无螺栓无挡肩扣件,由弹条、预埋铁座、绝缘挡块和钢轨缓冲垫组成。SK115型扣件是高速铁路用的一种扣件,具有高弹程等优点。扣件在实际使用中,由于弹条与预埋铁座或螺栓接触界面之间的摩擦磨损及材料性能等的影响,导致受力接触面积变化,造成弹条在其使用寿命周期内发生松动或断裂失效问题,使扣件系统扣压力变小,即弹条发生失效。本论文以失效的弹条为研究对象,结合显微硬度仪、光学显微镜(OM)、体式显微镜、扫描电子显微镜(SEM)等分析弹条的失效机理；并运用Solidworks和ABAQUS软件模拟分析弹条扣件的安装过程,分析扣件系统在不同工况下的响应,与实验结果相互印证,并提出一些相关建议和预防措施,得到结论如下：1.根据本研究结果表明：弹条与其他部件接触界面间存在严重的磨损；断裂失效的原因为表面缺陷、材料疏松和应力集中促进了裂纹的萌生和发展,导致弹条的断裂。建议弹条钢加工工艺过程中应当尽量避免材料内部气孔的产生,表面应尽量保证平滑,弹条使用时应注意防锈防腐蚀。2.建立了弹条Ⅲ型扣件三维实体模型,分析弹条上应力分布,结果表明：在弹条大圆弧处存在应力集中,此处剪应力最大促进微裂纹的形成,拉应力最大利于裂纹的扩展,此位置与实际结果断裂位置一致。3.研究分析了弹条与预埋铁座间的接触摩擦系数、法向位移载荷对弹条Miese应力、剪应力、Y向正应力和扣压力的影响。结果表明：随着摩擦系数的增加,弹条大圆弧处应力逐渐增加,更加有利于弹条在此处的裂纹萌生和扩展;扣压力逐渐降低,减弱扣件对轨道的作用；当法向位移载荷大于14mm时,弹条大圆弧的Mises应力会达到其屈服极限,迅速导致裂纹的萌生和扩展。更多还原

【Abstract】 The fastener which connect rails and sleepers to form the track panel it plays an important role to ensure the reliability and stability of the track, and has an important impact on the safety of the railway transport. The type III spring fastener is a new fastener which designed for the high-speed and heavy rail without bolts and shoulder block, it combined with the spring, the embedded iron socket, the insulating stopper and the rail cushion. The SKL15elastic fastener is a high-speed railway fastener with the advantage of high-elastic process. In actual use, as the influence of the friction and wear of the contact interface between the embedded iron seat or bolt and the spring, material properties and so on, the contact area in the force changes, resulting in the spring appears the problem of loosening or fracture failure in its life cycle, the pressure of the fastener system gets smaller, so that the spring becomes failure.This paper makes the failure of the spring as the object of the study, combined with micro hardness tester, optical microscopy (OM), stereo microscope, scanning electron microscope(SEM)and so on, it analysis the failure mechanisms of the spring, and use Solid works and ABAQUS software to simulate and analysis the installation process of the spring fastener, it analysis the response of the fastening system under different work conditions compared with the experimental results, and give some suggestions and preventive measures, The main results were as follows:1. According to the results of this study it show that the heavy wear exists in the contact interface between the spring and the other components; the result offracture failure is surface defects, loose material and stress concentration which promote crack initiation and development, resulting in the fracture of the spring. The machining process of the spring steel should try to avoid the generation of holes inside the material, the surface should try to ensure the smooth, and the use of the spring should pay attention to rust and corrosion. 2.The three-dimensional solid model of the type III spring fastener is established to analysis the stress distribution of the spring, the results showed that:the stress concentration existsin the big arc of the spring where the shear stress is the maximum to promote the formation of micro cracks, the max tensile stress conducive to crack propagation, this position is consistent with the actual results to fracture location.3. The influence of friction andnormal displacement load on Miese stresses of the spring, shear stress, the normal stress of Y direction and buckle pressure. The results showed that:With the increase in the coefficient of friction, the stress in the arc of the spring gradually increased, more conducive to the crack initiation and propagation; buckle pressure gradually reduced, weakened the role of the fastener to track; when the displacement load greater than14mm, the Mises stress of the big arc of spring reaches its yield limit, quickly lead to crack initiation and propagation.更多还原