Fatigue Damage Evaluation of Friction Stir Spot Welded Cross-Tension Joints Under Repeated Two-Step Force Amplitudes
Fatigue Damage Evaluation of Friction Stir Spot Welded Cross-Tension Joints Under Repeated Two-Step Force Amplitudes
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DOI：
10.1007/s11665-015-1534-x
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发表时间：
2015-06-01
影响因子：
2.3
通讯作者：
Fujii, Hidetoshi
中科院分区：
文献类型：
--
作者：
Joy-A-Ka, Sutep;Ogawa, Yuki;Fujii, Hidetoshi
本文研究了一种在两步力幅条件下评估 FSSW 交叉拉伸试件疲劳损伤的方法。在重复两步力幅的疲劳试验中，焊接接头的疲劳极限消失了。然而，使用修改后的迈纳规则进行的疲劳损伤评估在安全性方面犯了太多错误，因为修改后的迈纳规则往往会高估施加低于疲劳极限的力所造成的损伤。因此，可以确定，在本研究中使用的测试条件下，使用 Haibach 方法进行的疲劳损伤评估得到了准确的评估。在焊接区附近发生由外加力引起的显着塑性变形的情况下，基于迈纳法则的累积疲劳损伤值通常大于1。因此，重要的是要考虑累积损伤估计，该估计考虑了高力幅的预应变影响。
This paper investigates an approach to evaluate the fatigue damage of FSSW cross-tension specimens under two-step force amplitude conditions. In fatigue tests with repeated two-step force amplitude, the fatigue limit of the welded joint disappeared. However, the fatigue damage evaluation using the modified Miner's rule erred too much on the side of safety, as the modified Miner's rule tends to overestimate the damage by applied forces below the fatigue limit. Thus, it was determined that, within the testing conditions used in this study, the fatigue damage evaluation using Haibach's method yielded an accurate evaluation. In the case where significant plastic deformation caused by the applied force occurred near the welded zone, the cumulative fatigue damage value based on Miner's rule was often larger than unity. Therefore, it is important to consider a cumulative damage estimation that takes into account the effect of pre-strain from the high force amplitude.