Al-Li 8090 和 Ti-6Al-4V 的 20 kHz 微动疲劳研究

用超声疲劳试验技术研究了Ａｌ－Ｌｉ８０９０铝锂合金和Ｔｉ－６Ａｌ－４Ｖ钛合金在２０ｋＨｚ时的微动损伤现象。试验结果表明，在极高频率下，也有微动损伤发生，并可引发疲劳裂纹的萌生和扩展，导致微动疲劳破坏。

Study on Fretting Fatigue of Al Li 8090 and Ti 6Al 4V at Very High Frequency

The fretting fatigue was studied principally at low freqency, of some dozens hertz. Generally, the researchers admit that the fretting fatigue strength of materials rises with increasing frequency.In this paper,the experimental results obtained with the ultrasonic fatigue technique show that the fretting may exist also at very high frequency over 20kHz, it sets up a menace to the security of certain machines working in vibration condition. The relative slipe amplitude is an important factor, the larger is the amplitude, the more typical and more pronounced are the signs of fretting. In alloys Al Li 8090 and Ti 6Al 4V, the latter is very sensitive to vibratory fretting as to conventional fretting,and the fretting is very detrimental when the amplitude exceeds 0.8～1μm. The fretting due to high frequency triggers earlier cracks and leads to the rupture when the stress is high enough. The fatigue strength is reduced by vibratory fretting as by conventional fretting.