A failure criterion to explain the test specimen thickness effect on fracture toughness in the transition temperature region

作者：Meshii Toshiyuki^*; Lu Kai; Takamura Ryota

来源：Engineering Fracture Mechanics, 2013, 104: 184-197.

DOI：10.1016/j.engfracmech.2013.03.025

• Fracture mechanics
• Constraint effect
• Fracture toughness
• Cleavage fracture
• Transition temperature
• Thickness effect
• 3 PB specimen

This paper considered the test specimen thickness (TST) effect on the fracture toughness of a material J(c) in the transition temperature region for 3 point bending (3 PB) specimens. Fracture toughness tests and elastic-plastic finite element analyses (FEA) with nonstandard test specimens, which are non-standard because the specimen thickness-to-width ratio B/W was varied in the range of 0.25-1.5, were conducted. Based on these tests and the FEA results, it was demonstrated that the %26quot;planar%26quot; (4 delta(t), sigma(22c)) failure criterion-which states that cleavage fracture after significant plastic deformation occurs when the crack opening stress sigma(22) at a distance from the crack-tip that is equal to four times the crack-tip opening displacement delta(t) exceeds a critical value sigma(22c)-was verified to effectively explain the TST effect. This (4 delta(t), sigma(22c)) criterion also successfully predicted the tendency of J(c) to saturate to some bounding value for B/W = 1.0. This tendency was similar to that of the T-33-stress, which is the out-of-plane elastic crack-tip constraint parameter.

• 出版日期2013-5