Modeling the ductile to cleavage transition in steels and structures
Modeling the ductile to cleavage transition in steels and structures
复制标题
模拟钢材和结构中的延性到解理转变
DOI：
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发表时间：
2000
期刊：
影响因子：
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通讯作者：
Ma Sheikh
中科院分区：
文献类型：
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作者：
I. Howard;Z. H. Li;Ma Sheikh
铁素体钢的韧性损伤和随后的裂纹扩展及解理过程是在不同的控制显微组织特征的步骤中发生的。因此，这些有用的模型可以通过将韧性损伤或裂解机制与适当的、微观结构控制的细胞大小联系起来来尝试。此外，用于延性损伤的单元尺寸通常太大，无法用于裂纹尖端有限元，而裂纹尖端有限元需要精确分辨连续场中的大应变梯度，这代表了在重大损伤发展之前的变形。所需要的是一个允许（至少潜在地）存在多种尺寸的单元的有限元代码。这些考虑导致了不依赖网格的损伤力学建模，以及针对每种破坏机制具有适当单元尺寸的韧性-脆性转变模型。对于技术上有趣的问题，这些精细模型的复杂性需要非常大的计算时间。因此，我们对工程试验结果的预测使用了一种折衷的单尺寸单元模型来平衡每个失效过程的相互冲突的要求。本文叙述了这一理论的证明，并将其应用于两个大型纺丝筒试验的预测。这项工作说明了在严格的物理表示所需的详细准确性和捕获应用驱动的研究项目所需的实用主义之间可能出现的潜在冲突。本文最后讨论了这些方法及其有效领域之间可能存在的关系。
The process of ductile damage and subsequent crack growth and of cleavage in ferritic steels occur in steps whose controlling microstructural features are quite different. Useful models of these can, therefore, be attempted by associating the mechanisms of ductile damage or cleavage with an appropriate, microstructurally controlled, cell size. Furthermore, the cell size for ductile damage is typically too large to be used for the crack-tip finite elements that are required for accurate resolution of the large strain gradients in the continuum field that represents the deformation there prior to significant damage development. What is required is a finite-element code that allows (at least potentially) the presence of cells of more than one size. These considerations have led to mesh-independent damage mechanics modeling, and a model of the ductile-to-brittle transition that has appropriate cell sizes for each failure mechanism. The complexity of these refined models demands very large computational times for technically interesting problems. Accordingly, our predictions of the outcome of engineering tests have used a compromise single-size cell model chosen to balance the conflicting requirements for each failure process. The paper describes the proving of this, and its use in predicting two of the large-scale spinning cylinder tests. The work illustrates the potential conflict that may arise between the detailed accuracy required for rigorous physical representation and the pragmatism needed to capture the essentials of application-driven research programs. The paper ends with a discussion of the possible relations between these approaches and their areas of effectiveness.