PSI - Issue 51

Yu.G. Matvienko et al. / Procedia Structural Integrity 51 (2023) 76–80 Yu.G. Matvienko / Structural Integrity Procedia 00 (2022) 000–000

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4

structural steels. It can be seen that the normalized constraint corrected fracture toughness �� �� / ��� depends on the material properties and the crack aspect ratio (Fig. 1). The strain hardening exponent n significantly affects the normalized constraint corrected fracture toughness. The magnitude of the normalized constraint corrected fracture toughness decreases with the increase of the applied failure stress and the decrease of the crack aspect ratio to a certain values. Stabilization of the normalized constraint corrected fracture toughness is observed for some crack aspect ratios which are dependent on the material properties. The decrease in the normalized constraint corrected fracture toughness with decreasing the crack aspect ratio is due to the larger values of the fracture toughness ��� for shorter cracks. The trend of increasing the fracture toughness ��� with the decrease of the crack aspect ratio is confirmed by experimental data which was obtained by Sumpter (1993).

1.0

SECP specimen n=5

0.8

0.6

J Cmat /J mat

0.4

a/W =0.1 a/W =0.4 a/W =0.7

a/W =0.2 a/W =0.5 a/W =0.8

a/W =0.3 a/W =0.6

0.2

0 0.2 0.4 0.6 0.8 1.0 1.2 0

 L

Fig. 1. The normalized constraint corrected fracture toughness �� �� / ��� as a function of the applied stress ratio � and the strain hardening exponent for SECP specimens with different crack aspect ratio a/W . 5. Conclusions The following conclusions can be drawn. The J-A concept, based on the three-term asymptotic solution for elastic-plastic crack-tip stresses, and the cumulative damage rule are employed to construct the quantitative two-parameter elastic-plastic J-A criterion and the constraint corrected fracture toughness �� �� . The constraint corrected elastic-plastic fracture toughness �� �� is presented as a function of the crack-tip constraint parameter A , the strain hardening exponent, the yield stress and the applied failure stress. The effect of the constraint parameter and mechanical properties on the normalized constraint corrected fracture toughness is illustrated for single edge cracked plate ( ECP) with varying crack aspect ratios, the applied stress ratio � and the strain hardening exponent. The magnitude of the normalized constraint corrected fracture toughness decreases with the increase of the applied failure stress and the decrease of the crack aspect ratio to a certain values. References Anderson, T.L., 2005. Fracture Mechanics: Fundamentals and Applications. Taylor & Francis Group, Boca Raton. Ding, P., Wang, X., 2010. Solutions of the Second Elastic–Plastic Fracture Mechanics Parameter in Test Specimens. Engineering Fracture Mechanics 77, 3462-3480.