Stress-based fatigue life prediction models for AZ31B magnesium alloy under single-step and multi-step asymmetric stress-controlled cyclic loadings
Stress-based fatigue life prediction models for AZ31B magnesium alloy under single-step and multi-step asymmetric stress-controlled cyclic loadings
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DOI：
10.1016/j.commatsci.2013.02.023
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发表时间：
2013-06
影响因子：
3.3
通讯作者：
Y. Lin;Zheng-Hua Liu;Xiao-Min Chen;Jian Chen
中科院分区：
文献类型：
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作者：
Y. Lin;Zheng-Hua Liu;Xiao-Min Chen;Jian Chen
通过室温非对称循环应力控制试验，研究了热轧AZ31B镁合金的单轴棘轮疲劳和低周疲劳破坏行为。讨论了可变平均应力、应力幅值和应力率的加载历史对所研究的镁合金棘轮响应和疲劳寿命的影响。考虑棘轮损伤和疲劳损伤对材料失效的综合影响，建立了基于应力的疲劳寿命预测模型，用于评估单步和多步循环载荷下的低周疲劳寿命。结果表明：(1)较高平均应力或应力幅值的前应力循环抑制了后续较低平均应力或应力幅值循环的棘轮应变；(2)由于所研究的材料在室温下具有率无关的特性，变应力率加载历史对棘轮行为的影响不明显。(3)实验结果与预测结果的对比表明，所建立的模型能够较准确地估算热轧AZ31B镁合金在单步和多步非对称应力控制循环载荷作用下的低周疲劳寿命。
The uniaxial ratcheting and low-cycle fatigue failure behaviors of the hot-rolled AZ31B magnesium alloy are studied by the asymmetric cyclic stress-controlled experiments at room temperature. The effects of loading histories with the variable mean stress, stress amplitude and stress rate on the ratcheting respond and fatigue life of the studied magnesium alloy are discussed. Considering the combined effects of ratcheting damage and fatigue damage on the material failure, the stress-based fatigue life prediction models are developed to evaluate the low-cycle fatigue life under the single-step and multi-step cyclic loadings. Results show that (1) the prior stress cycling with high mean stress or stress amplitude restrains the ratcheting strain in the subsequent cycling with low mean stress or stress amplitude. (2) Due to the rate-independent property of the studied material at room temperature, the effects of the loading history with variable stress rate on the ratcheting behavior are not obvious. (3) The comparisons between the measured and predicted results confirm that the developed model can give an accurate estimate of the low-cycle fatigue life for the hot-rolled AZ31B magnesium alloy under the single-step and multi-step asymmetric stress-controlled cyclic loadings.