Influence of mean stress and variable amplitude loading on the fatigue behaviour of a high-strength steel in VHCF regime
Influence of mean stress and variable amplitude loading on the fatigue behaviour of a high-strength steel in VHCF regime
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DOI：
10.1016/j.ijfatigue.2013.04.015
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发表时间：
2014-05-01
影响因子：
6
通讯作者：
Lebahn, J.
中科院分区：
文献类型：
--
作者：
Sander, M.;Mueller, T.;Lebahn, J.
部件和结构经常暴露在非常高的循环次数。在本文的研究范围内，以应力比（R-ratio）表示的平均应力对高强度钢（34CrNiMo6）在轴向加载下VHCF状态下疲劳性能的影响进行了实验研究。对于两种分析的r比，裂纹主要在试样内部的非金属夹杂物处成核，形成鱼眼，但断口表面未见oda。因此，可以观察到连续的S-N曲线，其中斜率以及疲劳强度取决于r比。此外，到失效的循环次数受r比的影响。为了研究变幅对直升机寿命疲劳的影响，采用标准直升机载荷谱FELIX进行了变幅试验。变幅加载会在非金属夹杂物周围形成止动标记，用于计算疲劳裂纹扩展速率。根据重构顺序，VA试验的S-N曲线会向更高的寿命偏移。计算结果用于评价不同方法计算短裂纹扩展阈值范围和疲劳寿命。(C) 2013 Elsevier Ltd.版权所有。
Components and structures are often exposed a very high number of cycles. Within the scope of this paper the effect of the mean stress in terms of the stress ratio (R-ratio) on the fatigue properties of a high-strength steel (34CrNiMo6) in the VHCF regime was experimentally investigated under axial loading. For both analyzed R-ratios the cracks nucleate predominately at non-metallic inclusions in the interior of the specimen and a fish-eye is formed, but ODAs were not visible on the fracture surface. Thus, continuous S-N curves are observable, where the slopes as well as the fatigue strengths are dependent on the R-ratio. Moreover, the number of cycles to failure is influenced by the R-ratio. In order to investigate the influence of variable amplitudes on the lifetime fatigue tests were performed using the standard helicopter load spectrum FELIX. Due to variable amplitude loading arrest marks are created surrounding the non-metallic inclusion, which are used to calculate the fatigue crack growth rate. The S-N curves of the VA tests are shifted to higher lifetimes depending on the reconstruction sequence. The results are used for the evaluation of different approaches calculating short crack growth threshold ranges and the fatigue lifetime. (C) 2013 Elsevier Ltd. All rights reserved.