摘要
本文建立由铁路辙叉和列车车轮组成的三维弹-塑性有限元模型,研究高锰钢辙叉心轨的应力/应变场。文中考虑辙叉心轨在顶宽50mm处的两种服役状态——服役前期未发生加工硬化和服役后期发生加工硬化,分析加工硬化对心轨应力/应变大小和分布的影响。对服役加工硬化的情况,考虑到距离工作表面不同深度处辙叉材料性能的不同,将心轨局部模型分层,并设置各层的材料性能;对未发生加工硬化的情况,为模型设置均匀的材料性能。结果表明,两种服役状态下辙叉心轨的von Mises应力和等效塑性应变均随深度的增加先快速增大,然后逐渐减小;与服役初期相比,服役后期心轨的最大等效应力增大约23%,最大等效塑性应变则降低约40%;塑性变形区域也明显减小,这是由于心轨在服役加工硬化后屈服强度已大幅提高。因此,在很大程度上,服役后期的加工硬化起着抑制心轨顶面塌陷和飞边形成的作用。此外,与未加工硬化心轨相比,加工硬化后心轨的最大等效应变与工作表面的距离由0.8mm增大到了1.5mm,这表明易产生裂纹的位置有远离心轨表面的趋势。
A three dimensional elastic-plastic finite element model consisting of a railway crossing and a train wheel was established to investigate the stress/strain field in a high manganese steel crossing nose.Two service states of the crossing at a nose width of 50 mm were considered in the paper,i.e.non-work hardening corresponding to the early service stage and work hardening corresponding to the later service stage,and the influence of service work hardening on the magnitude and distribution of stress/strain in the crossing nose was analyzed.In the case of simulation of service work hardening,a layered model was constructed and various material properties were assigned to corresponding layers,according to the effect of the distance from the surface of an actual work-hardened crossing nose on the material properties,while a homogeneous material property was assigned to the entire model with non-work hardening.The results indicate that,during both the early and later service stages,the von Mises stress and equivalent plastic strain rapidly increase and then gradually decrease with the increase of the depth.As compared with the early service stage,during the later service stage,the maximum von Mises stress of the crossing nose increased by about 23%,while the maximum equivalent plastic strain decreased by about 40%,and the plastic strain zone reduced significantly.The reason for this is due to the largely increased yield strength of the crossing nose after service work hardening.It is there-fore believed that the surface quashing and the formation of overlap in the crossing nose may be largely suppressed owing to the service work hardening.Furthermore,as compared to the non-work-hardened crossing nose,the distance between the location of the maximum equivalent plastic strain of the work-hardened crossing nose and the surface of the crossing nose increases from 0.8mm to 1.5mm,indicating that crack initiation site tends to move to locations farther away from the crossing nose surface.
出处
《铁道学报》
EI
CAS
CSCD
北大核心
2015年第2期85-90,共6页
Journal of the China Railway Society
基金
国家杰出青年科学基金(50925522)
国家自然科学基金(51171166)
河北省自然科学基金(E2011203066)
