Ratcheting assessment of steel alloys under step-loading conditions
Ratcheting assessment of steel alloys under step-loading conditions
复制标题
DOI：
10.1016/j.matdes.2013.04.047
复制
发表时间：
2013-10
影响因子：
8.4
通讯作者：
G. Ahmadzadeh;A. Varvani-Farahani
中科院分区：
文献类型：
--
作者：
G. Ahmadzadeh;A. Varvani-Farahani
本研究检验了最近修改的硬化规则的能力，以表征经受多步单轴应力循环的材料的棘轮响应。修改后的硬化规则是在阿姆斯特朗-弗雷德里克（A-F）硬化规则的基础上通过实施新的棘轮速率相关系数γ2和δ而开发的。这些系数是通过针对任何给定应力水平的校准曲线来估计的，该应力水平是根据各种循环应力水平下的单轴单步棘轮响应定义的。在平均应力恒定的情况下，随着加载历史步骤中应力幅度的增加，棘轮应变逐渐增加。当平均应力值增加时，对于恒定应力幅值的阶跃加载，类似的响应也很明显。对于高-低历史，预测的棘轮应变从较高到较低幅度的趋势与实验数据一致。然而，高低阶跃载荷中预测的棘轮应变值与实验的棘轮应变值的差异是由于修改的运动硬化规则中平移屈服面的形状和尺寸的恒定性造成的。采用修改后的硬化规则来评估 SS316L、SA333、SS316L(N) 和 1070 钢合金在各种阶跃加载条件下的棘轮响应。与实验棘轮应变相比，发现各种应力水平下的预测棘轮数据具有良好的一致性。
The present study examines the capability of a recently modified hardening rule to characterize ratcheting response of materials subjected to multi-step uniaxial stress cycles. The modified hardening rule was developed based on Armstrong–Frederick (A–F) hardening rule through implementing new ratcheting rate dependent coefficientsγ2andδ. These coefficients were estimated by means of calibrated curves for any given stress levels defined from the uniaxial single-step ratcheting response at various cyclic stress levels. At a constant mean stress, ratcheting strain progressively increased as stress amplitude over steps of loading history increased. Similar response was also evident for step-loading with constant stress amplitude while the values of mean stress increased. For high–low histories, the trend of predicted ratcheting strain from higher to lower magnitudes found agreeable with that of experimental data. The discrepancy of the predicted and experimentally ratcheting strain values in the high–low step loading however was due to constancy in the shape and size of translating yield surface in the modified kinematic hardening rule. The modified hardening rule was employed to assess ratcheting response of SS316L, SA333, SS316L(N) and 1070 steel alloys under various step-loading conditions. Predicted ratcheting data at various stress level were found in good agreements as compared with the experimental ratcheting strains.