A simplified method for evaluation of brittle crack arrest toughness of steels in scaled-down bending tests
A simplified method for evaluation of brittle crack arrest toughness of steels in scaled-down bending tests
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小型弯曲试验中钢脆性裂纹止裂韧性评估的简化方法
DOI：
10.1016/j.engfracmech.2019.03.047
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发表时间：
2019
影响因子：
5.4
通讯作者：
Teppei Okawa
中科院分区：
文献类型：
--
作者：
Yuki Nishizono;Shuji Aihara;Tomoya Kawabata;Teppei Okawa
用于表征高强度船用钢脆性止裂韧性的拉伸载荷下的宽板止裂试验需要较高的经济成本和较长的研制周期，因此仍然存在使用缩小试样的简化评估的大量工业需求。另一种方法，使用一个单一的边缘切口弯曲试样，它假设在裂纹扩展过程中的完整的载荷重分布，最近提出的。然而，证实了使用该方法获得的结果与使用宽板试验获得的制动韧性表现出低相关性。一个新的缩小版本的裂纹止裂试验在弯曲载荷下和一系列简化的评价的基础上的动态弹塑性有限元分析，以表征裂纹止裂性能的两种类型的钢板在这项调查中。试样是在等温环境中承受三点弯曲载荷的单边缺口锥形板。选择几何形状，以便使用FEA计算的动态裂纹驱动力随着裂纹扩展单调减小。动态有限元模拟采用了考虑动态效应的简化分析方法，假定裂纹扩展速度为常数，裂纹前缘为平直，输出裂纹扩展前的张开应力分布。实验获得的值的止裂裂纹长度和分析获得的动态应力强度因子的过渡曲线被用来表征裂纹止裂性能的两种钢。使用简化的方法在这项调查中得到的结果表现出高度的相关性与制动韧性使用宽板裂纹制动试验。
The wide-plate crack arrest test under tensile load for characterizing the brittle crack arrest toughness of high strength shipbuilding steel requires high economical cost and long lead-time, so there is still a substantial industry need for the simplified evaluation using the scaled-down specimen. The alternative method using a single edge-notched bending specimen, which assumes the complete load redistribution during the crack propagation, was recently proposed. However, it was confirmed that the results obtained using this method exhibited a low correlation with the arrest toughness obtained using the wide-plate tests. A new scaled-down version of the crack arrest test under bending load and a series of simplified evaluation based on the dynamic elasto-plastic FEA were introduced to characterize the crack arrest performance of the two types of steel plates in this investigation. The specimen is a single edge-notched tapered plate subjected to a three-point bending load in an isothermal environment. The geometry was selected so that the dynamic crack driving force calculated using FEA decreases monotonically with the crack propagation. For adopting a simplistic analytical approach considering the dynamic effect, the dynamic FEA simulation assumed the constant crack velocity and flat crack front and output the opening stress distributed ahead of the growing crack. The experimentally obtained values of the arrested crack length and the analytically obtained transition curves of the dynamic SIF were employed to characterize the crack arrest performance of the two steels. The results obtained using the simplified method developed in this investigation exhibited a high correlation with the arrest toughness obtained using the wide-plate crack arrest test.