Verification of crack opening criterion deduced by newly derived micro-crack evolution equation

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• 作者：Michiaki Kobayashi ; ¹ ; ^{kobayasi@mail.kitami-it.ac.jp}
• 关键词：Crack opening criterion ; Micro-crack evolution equation ; Crack opening analysis ; Brittle fracture ; Fracture mechanism ; Strain gradient
• 刊名：International Journal of Solids and Structures
• 出版年：2017
• 出版时间：February 2017
• 年：2017
• 卷：106-107
• 期：Complete
• 页码：139-151
• 全文大小：2368 K
• 卷排序：106

文摘

The author proposed a criterion of micro-crack nucleation, which was deduced theoretically by shock wave theory, and derived new micro-crack evolution equations. The new micro-crack evolution equation suggested that the strain gradients play an important role in the fracture mechanism. In this paper, based on the crack opening criterion deduced by the new micro-crack evolution equation and the stresses, strains and strain gradients substituted by the stress intensity factor the fracture mechanisms of metallic and ceramic materials are examined using those well-known data, i.e. fracture toughness and so forth, to verify the crack opening criterion. Moreover, the fracture toughness of the plane stress condition is estimated and becomes almost 1.2–1.8 times as much as the plane-strain fracture toughness generally so called “fracture toughness”. Even though the two-dimensional analytical version is adopted, the crack opening criterion gives the useful information that is verified by comparisons of the estimated yielding stress of metallic materials, the estimated bending facture strength of ceramic materials and the critical time from yielding stress/bending fracture strength loading to crack opening with those of well-known data of both materials. Therefore, it is expected that the micro-crack evolution equation and the crack opening criterion would give the useful tool to examine the fracture mechanism.