7075铝合金超声多轴疲劳断裂行为
Multiaxial Fatigue Fracture Behavior of Al 7075 under Ultrasonic Loading
韩广玲 1黄志勇 1王建 1申杰斌2
作者信息
- 1. 四川大学 空天科学与工程学院,成都 610065
- 2. 四川大学 建筑与环境学院,成都 610065
- 折叠
摘要
针对航空发动机相关部件缺少铝合金7075-T6的超高周多轴疲劳S-N数据与疲劳断裂机制等相关数据问题,设计了新型超声多轴疲劳增幅杆和多轴疲劳试件,与超声换能器组成超声多轴疲劳设备,实现拉压和扭转应力的同时加载,获得了在109循环数范围内的超高周多轴疲劳S-N曲线.此外,在扫描电子显微镜(SEM)下观察多轴疲劳试件断口并进行分析.结果表明:当疲劳寿命处于高周(HCF)范围内时,多轴试件受到扭转应力的影响,裂纹从表面及次表面开始萌生,疲劳裂纹扩展路径上出现了大量的疲劳孔洞;在较大的裂纹尖端剪切力的高裂纹增长率影响下,疲劳孔洞在裂纹萌生点附近聚集.当疲劳寿命处于超高周(VHCF)范围时,裂纹萌生位置从表面逐步过渡到内部,内部裂纹萌生机制具有鱼眼特征,鱼眼中心出现的破碎颗粒起到应力集中点的作用,使裂纹从内部萌生.
Abstract
In response to the lack of relevant S-N data of multiaxial Very High Cycle Fatigue and fatigue fracture mechanism of aluminum alloy 7075-T6 for related aeroengine components,a new type of ultrasonic multiaxial fatigue horn and multiaxial fatigue specimens were designed,which were combined with the ultrasonic transducer to form an ultrasonic multiaxial fatigue equipment to realize the simultaneous loading of tension,compression,and torsional stress,and the multiaxial Very High Cycle Fatigue S-N curve was obtained in the range of 109 cycles.In addition,the fracture surfaces of multiaxial fatigue specimens were observed and analyzed under a Scanning Electron Microscope(SEM).The results show that when the fatigue life is in the range of High Cycle Fatigue(HCF),the cracks of multiaxial specimens initiate from the surface and subsurface under the influence of torsional stress,and a large number of fatigue voids appear on the fatigue crack growth path.Under the influence of the high crack growth rate of large crack tip shear force,the fatigue voids accumulate near the crack initiation point.When the fatigue life is in the range of Very High Cycle Fatigue(VHCF),the crack gradually transits from surface initiation to internal initiation,and the internal crack initiation mechanism has the characteristics of a fish-eye.The broken particles in the center of the fish-eye act as the stress concentration points,causing cracks to initiate from the interior.
关键词
7075铝合金/多轴疲劳/裂纹萌生/疲劳孔洞/鱼眼/航空发动机Key words
7075 aluminum alloy/multiaxial fatigue/crack initiation/fatigue voids/fish-eye/aeroengine引用本文复制引用
出版年
2024
NETL
NSTL
万方数据