摘要
针对大模数齿条的疲劳寿命难以精确计算问题,对大模数表面淬火齿条的裂纹扩展规律进行了研究。建立了含共线初始双裂纹的齿条FRANC3D模型,齿条啮合区离散为15个区域载荷;分析了表面感应淬火齿条硬度分布、残余压应力分布对疲劳裂纹扩展寿命的影响,推导了齿条的断裂韧度K_(IC)与应力强度因子门槛值△K_(th);运用FRANC3D软件,对双共线初始裂纹在三种水平间距下的裂纹扩展、联通、继续扩展过程进行了仿真,得出了应力强度因子幅值△K随裂纹深度a扩展的表达式;根据裂纹扩展速率da/dN与△K、K_(IC)、△K_(th)的关系,预测了三峡升船机齿条的寿命N。研究结果表明:齿条满足疲劳寿命要求,但表面感应淬火降低了齿条的疲劳寿命;硬度分布对于裂纹扩展的促进作用大于残余压应力的抑制作用。
Aiming at the problem of accurate analysis for fatigue life of large modulus rack,the propagation of crack for large modulus quenched rack was studied.A FRANC3D model of the rack with initial collinear double cracks was established,the meshing area of rack was divided into 15 area foods.The influence of surface induction quenching rack hardness distribution and residual compressive stress distribu-tion on fatigue crack propagation life was analyzed,and the fracture toughness KIC and the threshold value of stress intensity factorΔKth of the rack were derived.With FRANC3D,the process of crack propagation,connection and continuous propagation under three horizontal spacing was simulated,and the expression of stress intensity factor amplitudeΔK with crack depth a was obtained.In accordance with the relation-ship between crack growth rate da/dN andΔK,KIC,ΔKth,the residual fatigue life of rack in the Three Gorges ship lift N was predicted.The results indicate that the rack meets the fatigue requirements.However,the fatigue life of the rack is reduced,the effect of hardness distribu-tion on the crack growth is greater than that of the residual compressive stress.
作者
路卫兵
俞歌
程熊豪
石端伟
张阳
LU Wei-bing;YU Ge;CHENG Xiong-hao;SHI Duan-wei;ZHANG Yang(China Three Gorges Corporation,Beijing 100038,China;School of Power and Mechanical Engineering,Wuhan University,Wuhan 430072,China;Key Laboratory of Hydraulic Machinery Transient,Ministry of Education,Wuhan 430072,China)
出处
《机电工程》
CAS
北大核心
2020年第1期44-48,共5页
Journal of Mechanical & Electrical Engineering
基金
国家重点研发计划项目(2016YFC0400202)
