轨道连接处缺陷对起重机运行冲击系数及疲劳剩余寿命的影响  

Influence of Rail Joint Defects on the Running Impact Coefficient and Fatigue Residual Life of Crane

作　　者：辛运胜 董青[1] 徐格宁[1] XIN Yunsheng;DONG Qing;XU Gening(School of Mechanical Engineering,Taiyuan University of Science and Technology,Taiyuan 030024)

机构地区：[1]太原科技大学机械工程学院,太原030024

出　　处：《机械工程学报》2020年第14期254-264,共11页Journal of Mechanical Engineering

基　　金：“十三五”国家重点研发计划(2017YFC0805703);山西省高等教育科技创新(2019L0649);山西省应用基础研究计划(201901D211288);山西省“1331工程”重点学科建设计划经费;山西省科技重大专项(20181102002);太原科技大学博士科研基金(20182037);山西省优秀博士奖励资助基金(20192018)资助项目。

摘　　要：为了分析起重机运行过程中轨道连接处缺陷对金属结构冲击系数的影响,通过正、余弦函数分别模拟高低缺陷和间隙缺陷所引起的不平度,并提出起重机越过轨道缺陷过程的动力学模型。理论推导起重机通过轨道连接处高低缺陷和间隙缺陷时的运行冲击系数方程,并将其与GB/T3811:2008和ISO8686—1:2012中方法进行形式和结果的比较,从而证明理论推导结果的正确性。基于起重机车轮尺寸及两种轨道缺陷不平度函数,分析轨道连接处高低缺陷和间隙缺陷发生耦合作用的临界条件,结果表明高低缺陷在冲击过程中起主要作用,二者同时存在时可忽略间隙缺陷影响。通过试验测试满载工况下无轨道缺陷和7mm高低缺陷时主梁最危险点的应变时间历程,并计算危险点的最大应力;将理论推导的运行冲击系数应用到有限元模型中,计算在无轨道缺陷和7mm轨道高低缺陷时对应测点的最大应力值,有限元分析结果与试验测试相对误差为2.63%,从而通过工程试验验证运行冲击系数理论推导的正确性。分析轨道缺陷对起重机剩余寿命的影响发现,起重机的临界裂纹长度、疲劳剩余寿命均随着轨道高低缺陷增大而减小,而影响度随着轨道缺陷增大而增大,轨道高低缺陷增大会使运行冲击系数增大且导致起重机主梁剩余寿命降低。In order to study the influence of impact coefficient of rail defects on crane operation,the unevenness function caused by step defects and gap defects is simulated by sine and cosine functions respectively,and the crane dynamics model of the running process under the rail defects is proposed.The expression of the impact coefficient of crane operation under step defects and gap defects is derived.The feasibility of the calculation results is verified by comparison with GB/T 3811:2008 and ISO 8686—1:2012.Based on the structural parameters and the characteristics of the rail defects,the critical conditions for the coupling of step defects and gap defects are analyzed.The results show that step defects play a major role in the impact process,and the gap defects can be ignored when both of them exist at the same time.The strain time history of the most dangerous point of the main beam without rail defect and 7 mm step defect under full load is tested respectively,and the maximum stress of the dangerous point is calculated.The theoretical calculation of running impact coefficient is applied to the finite element model to calculate the maximum stress value of corresponding measuring point under two different situations.The error between the finite element model and the experimental results is 2.63%,which verifies the correctness of the theoretical calculation.Analysis of the influence of rail defects on the remaining life of the crane can be found as follows:the critical crack length and fatigue residual life of the crane decrease with the increase of rail step defect,and the influence degree increases with the increase of rail defect.The increase of the step defects of the rail will increase the impact coefficient and reduce the remaining life of the main girder of the crane.

关 键 词：起重机 运行冲击系数 轨道连接处缺陷 试验验证 剩余寿命 

分 类 号：TH21[机械工程—机械制造及自动化]