Experimental Study and Life Prediction of Bolt Loosening Life under Variable Amplitude Vibration

Table 3

Loosening vibration times of each amplitude grade.

Amplitude grade	Average vibration times for reaching 90% residual preload	Average vibration times for reaching 80% residual preload	Average vibration times for reaching 70% residual preload
1 mm	12	63	193
0.8 mm	1230	2020	2260
0.6 mm	3265	4725	5150
0.4 mm	8590	10740	11718
0.3 mm	15205	19097	Not achieved