【作者】 梁红琴；

【导师】 赵永翔；

【作者基本信息】 西南交通大学 ， 载运工具运用工程， 2014， 博士

【摘要】 开展了典型动车组拖车轮轴的可靠性分析研究。考虑轮对中车轮-车轴-制动盘-轴承-轴箱之间的多重过盈装配关系,以及轮对与外界的物理接触关系,以等效刚度虚拟轴承代替真实的轴承,克服模型中宏观接触模型与轴承内微观接触模型不能相容求解的难题,建立了所研究动车组拖车轮对的有限元集成模型。进一步结合规范规定的极限机械载荷、疲劳强度考核载荷和线路谱载荷,完成相关工况下轮对的弹塑性有限元集成计算,并根据计算结果,针对轮轴完成了如下可靠性分析评价工作：(1)开展了轮轴概率极限机械强度评价工作。依据标准AAR S 660规定的极限机械载荷及有限元计算获得的轮轴应力,以及材料的极限强度,概率评价结果表明：轮座内侧是车轴von Mises应力水平最大部位,在置信度97.5%下的可靠度大于0.9999。车轮内侧辐板向轮辋过渡起始部位是von Mises应力水平最大部位,在置信度97.5%下的可靠度水平大于0.9999。(2)开展了轮轴概率疲劳耐久性强度评价工作。依据标准EN13979-1考核车轮疲劳强度的直道、弯道和道岔运行3工况及对应的3个制动工况载荷,结合有限元集成计算结果及材料-结构的耐久性疲劳强度数据,开展了轮轴疲劳强度评价,结果表明：弯道运行-制动工况下是轮轴疲劳强度考核的最危险工况；该工况下车轴轮座内侧是von Mises应力幅最大部位,但在C=97.5%下其疲劳耐久性强度的可靠度大于0.9999；考察车轮径向应力幅,辐板外侧向轮辋过渡部位是径向应力幅值最大部位,但在置信度C=97.5%下疲劳耐久性强度的可靠度大于0.999；考察车轮主应力范围,同样揭示辐板外侧向轮辋过渡部位是主应力范围最大部位,但在置信度C=97.5%下疲劳耐久性强度的可靠度大于0.999。(3)探索了轮轴谱载荷的疲劳可靠性分析方法。基于一段线路检测轮轨接触谱载荷,应用“二次多项式”回归方法,经过“2n+l”(n为轮对模型中的主动力元素个数)次有限元集成计算,获得了轮轴关键部位的载荷-应力转换方程,获得该部位相应的谱应力；进而应用超长疲劳寿命可靠性分析法,完成了疲劳可靠性分析评价。结果表明：轮座内侧仍然是车轴谱载荷下当量von Mises应力幅最大的部位,但在在97.5%置信度、400万km寿命下,可靠度仍然大于0.999。剪应力幅是车轮疲劳损伤速度最快因素。与前面设计疲劳强度考核结果不同,车轮外侧向轮毂过渡部位是车轮辐板最危险部位,轮毂孔内侧边缘是该车轮轮毂的最危险部位,但在期望置信度97.5%水平、寿命大于400万km条件下,其可靠度仍然大于0.999；踏面以下1.5mm处,是最易发生剥离的深度,在97.5%置信度水平、可靠度为0.99时,裂纹萌生寿命低于60万km。论文工作,为典型拖车轮轴的应力有限元科学计算、改进轮轴设计和进行服役科学管理,提供了指导。更多还原

【Abstract】 Reliability analysis is carrieded out for a typical non-powered wheelset of EMU. Considering the multi-interference fits between wheel-axle-brake plates-bearing-axlebox in the wheelset and the physical wheel-tract contact relation out of wheelset, a finite element (FE) method integrated modeling is constructed for the wheelset, in which the bearing is replaced using its virtual form with an equivalent stiffness to the true bearing, so that the incompatibility is overcome between the macro-contact models of multi-interference fits and the micro-contact models of rollers-raceways in the bearings and and the FE method is feasible for the wheelset. Further, the following reliability analysis is carried out to the wheel and axle under using related integrated calculations to the wheelset:(1) Probabilistic assessment is performed for extreme mechanical strength check. Stresses are obtained for the wheel and axle by the AAR S 660 coded critical mechanical loadset. A probabilistic assessment is made by the probabilistic material mechanical properties. Results reveal that critical location of the axle is at the inner of wheel seat. Critical location for the wheel is at the start point of transition curve from inner web to rim of the wheel. But their reliability levels are both greater than 0.9999 with a confidence 97.5 percentage.(2) Probabilistic assessment is tried for fatigue durability strength check. Stresses are calculated by the EN 13979-1 coded three kinds of loadsets including train runs on straight line, curved line, and switch piece, respectively, and the corresponding braking cases. Combining the materials-to-structured fatigue durability properties, a probabilistic assessment of fatigue durability is performed to the wheel and axle, respectively. Results show that critical runing operation for the axle is at braking case on curved line and critical location is similar to extreme mechanical strength checking case at the inner wheel seat. But reliability level is greater than 0.9999 with a confidence 97.5 percentage. For the wheel, both assessment methods of radial stress amplitude and principal stress amplitude are applied. Critical runing operation is both at braking case on curved line and critical location is both at the start point of transition curve from outer web to rim of the wheel. But reliability levels are all greater than 0.999 with a confidence 97.5 percentage.(3) Spectral load based reliability analysis is explored for the wheel and axle. Spectral stresses of the wheel and axle are estimated using the regression equation of squeres ploynomial, which is used for converting the loadset of wheelset to local stress of wheel or axle. The ploynomial comes from regression to the stress data of 2n+l times FE integrated calculations using the loadset of spectral load sequence, where n represents the number of active loading elements for the wheelset. A piece of spectral load sequence for the wheelset from on-line inspection is used for the present explortation. Results give that critical location is still at the inner wheel seat for the axle. Reliability level is greater than 0.999 at a confidence of 97.5 percentages and expected fatigue life of 4,000,000 km. Cyclic shear stressing is the key element to result in fatigue damage of the wheel. Different from the above design fatigue strength check, present critical location for wheel web is at start point of the curved line from outer web to gub. Inner bound of the hub hole is critical location for the wheel hub. But the above locations hold reliability levels greater than 0.999 at the confidence of 97.5 percentage and the expected life of 4,000,000 km. What most valuable noted is that the tread sub-face of 1.5 mm deepth holds a maximum equivalent shear stress amplatude to result most possibly in spalling of surface lay material from the tread. The cracking life for this spalling start is lower that 600,000 km at confidence of 97.5 percentage and expected reliability of 0.99.The present work provides a basis for guiding stress calculation, design improvement and service management of the wheelset.更多还原