A stress-weighted ductile fracture model for steel subjected to Ultra Low Cycle Fatigue
A stress-weighted ductile fracture model for steel subjected to Ultra Low Cycle Fatigue
复制标题
DOI：
10.1016/j.engstruct.2021.112964
复制
发表时间：
2021-10
影响因子：
5.5
通讯作者：
Christopher Smith;A. Ziccarelli;M. Terashima;A. Kanvinde;G. Deierlein
中科院分区：
文献类型：
--
作者：
Christopher Smith;A. Ziccarelli;M. Terashima;A. Kanvinde;G. Deierlein
提出了一个新的判据来模拟超低周疲劳(ULCF)引起的延性断裂。在前人研究的基础上，新的断裂准则扩大了ULCF模型的范围，以考虑钢结构中可能遇到的更广泛的多轴应力和应变状态。该模型得到了孔洞扩展的有限元塑性模拟和断口断口分析的支持，将损伤累积描述为塑性应变、应力三轴性和Lode应力参数的函数。在局部应变和应力的任意循环加载历史上对损伤率模型进行积分，以预测ULCF断裂。所提出的判据(称为应力加权延性断裂模型-SWDFM)得到了两个等级的低碳结构钢(A572和A36)的66个试件尺寸试验的支持。这些试验询问一系列正负应力三轴性，绝对值在0.1到1.6之间，Lode应力参数在0到1之间，以及单调和循环加载历史。SWDFM标准只需要对本研究中所调查的材料进行两个材料参数的校准，并使用平均误差评估和交叉验证分析来对照实验测试数据进行评估。对其他三个ULCF破裂标准进行了类似的评估和比较。结果表明，SWDFM模型能够在较宽的应力状态和加载历史范围内准确地预测ULCF的萌生，这表明该模型很好地反映了ULCF的微观力学机制。
A new criterion is proposed to simulate the initiation of ductile fracture due to Ultra-Low Cycle Fatigue (ULCF). Building on previous research, the new fracture criterion broadens the scope of ULCF models to account for a broader range of multi-axial stress and strain states that may be encountered in steel structures. The model formulation, supported by observations from finite element plasticity simulations of void growth and fractographic analyses of fracture surfaces, describes damage accumulation as a function of plastic strain, stress triaxiality, and the Lode stress parameter. The damage rate model is integrated over arbitrary cyclic loading histories of local strains and stresses to predict ULCF fracture. The proposed criterion (termed the Stress Weighted Ductile Fracture Model – SWDFM) is supported by a series of 66 coupon scale experiments on two grades of low-carbon structural steel (A572 and A36). These tests interrogate a range of positive and negative stress triaxiality with absolute values between 0.1 and 1.6, Lode stress parameters between 0 and 1, and monotonic and cyclic loading histories. The SWDFM criterion, which requires the calibration of only two material parameters for the materials investigated in this study, is evaluated against the experimental test data using an average-error assessment as well as a cross-validation analysis. Three other ULCF rupture criteria are similarly assessed and compared. The SWDFM is shown to accurately predict ULCF initiation over a wide range of stress states and loading histories, suggesting that the model represents well the micro-mechanical mechanisms of ULCF.