摘要
针对航空发动机压气机叶片复杂载荷环境下的超高周疲劳问题,开展了TC4钛合金三点弯曲超高周疲劳试验,研究其在弯曲加载下的超高周疲劳破坏行为。疲劳试验结果表明:在两种应力比(R=0.3,0.5)下,当循环次数超过107次时,试件仍发生疲劳断裂,S-N曲线均呈现双线性特征;SEM断口分析表明,随着最大应力的降低,裂纹萌生位置由试件表面向次表面转移,疲劳裂纹萌生是表面滑移和内部解理断裂之间相互竞争的结果;基于疲劳寿命建立模型分析了应力比对2种裂纹萌生机制之间竞争行为的影响。采用红外热像仪监测试件表面的温度,高周疲劳试件的温度变化分为4个阶段:稳定升高、稳定降低、快速升高和快速降低,而超高周疲劳试件的温度变化分为3个阶段:稳定升高、快速升高和快速降低。最后,阐述了疲劳过程中生热和传热的特点,并分析了温度变化与应力分布的关系。
Aiming at the very-high-cycle-fatigue(VHCF) of aeroengine compressor blades under complex loading,three-point bending ultrasonic fatigue tests of TC4 titanium alloy under stress ratio R of 0.3 and 0.5 were performed,and failure mechanisms of VHCF under three-point bending was also investigated.Test results show that when the number of cycles exceeds 107 cycles,specimens under the two stress ratios R of 0.3,0.5 fail and S-N curves present a bilinear characteristic.SEM analysis indicates that the crack initiation sites are transferred from the surface to the sub-surface with the decrease of the maximum stress.Fatigue crack initiations are results of competition between surface slip and internal cleavage fracture.Then a model based on fatigue life was proposed to describe the competition between the two mechanisms,which is in agreement with the experimental results.The temperature of the specimen surface was monitored by an infrared camera.Its change can be divided into four stages in the high-cycle-fatigue(HCF) regime :steady rising,steady decreasing,fast rising and fast decreasing.While it can be divided into three stages in the VHCF regime :steady rising,fast rising and fast decreasing.Finally,the characteristics of heat production and transfer were described,and the correlation between temperature and stress distribution was analyzed.
作者
鲁凯举
程礼
陈煊
陈超
焦胜博
刘景元
鲍学淳
Lu Kaiju;Cheng Li;Chen Xuan;Chen Chao;Jiao Shengbo;Liu Jingyuan;Bao Xuechun(Air Force Engineering University,Xi’an 710038,China;Co-Innovation Center for Advanced Aero-Engine,Beijing 100191,China;Air Force Aviation University,Changchun 130000,China)
出处
《稀有金属材料与工程》
SCIE
EI
CAS
CSCD
北大核心
2019年第10期3175-3182,共8页
Rare Metal Materials and Engineering
基金
国家重点基础研究发展计划(“973”计划)(2015CB057400)
