高-低加载下载荷幅值对疲劳寿命的影响

摘要

对拉剪电阻点焊试样进行了两级加载疲劳试验，试验中，第1组试件的2个载荷水平均在低周范围，第2组试件的一个载荷水平在低周范围，另一个在高周范围。结果表明，对于高-低加载，其存在过载延迟现象，并且在低-中高周疲劳的过程中，存在明显寿命增加的现象。利用线性损伤累积准则，分析了两级加载下的累积损伤规律和载荷幅值差异对于累积损伤的影响。%Tensile-shear spot welding samples under two level loading was tested,there were two groups of load level in the experiment,in the first group,two load levels were all in the low load level,in the second group,the other one was in the low load level,and it was in high load level.The results showed that there wais overload retardation phenomenon in high-low load,and the fatigue life at low-high cycle increased significantly.By using the linear cumulative damage rule,the cumulative damage law under two level loading was analyzed,and the differences of load amplitude for the effect of cumula-tive damage were also analyzed.