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对拉剪点焊试样进行了两组不同载荷水平的两级低-高循环加载试验,得到随第一级载荷下循环数变化,点焊试样的剩余寿命和总疲劳寿命变化规律。使用Miner线性累积损伤理论计算得到两种不同载荷水平下试样总的疲劳损伤。结果表明:对于低-高加载,随着低载水平下循环数的增多,高载荷水平下的剩余寿命以及损伤值呈逐渐减小趋势,总疲劳寿命逐渐增大。当低载水平载荷幅值较小时,点焊试样破坏时的累计损伤值普遍存在小于1的现象,且这种现象可能对疲劳寿命估算存在一定的影响。
Two sets of low-high cyclic loading tests with different load levels were carried out on the pull-spot-welded samples. The variation of the number of cycles under the first-stage load, the remaining life of the spot-welded samples and the variation of the total fatigue life were obtained. Using Miner’s linear cumulative damage theory, the total fatigue damage of specimens at two different loading levels was calculated. The results show that for low-high loads, the residual life and the damage value at high load level decrease gradually with the increase of cycles under low load level, and the total fatigue life increases gradually. When the load at low load level is small, the cumulative damage value of spot welding specimen damage is generally less than 1, and this phenomenon may have some impact on fatigue life estimation.