On the determination of JIC using the stretch zone width method
Suresh RKV, Ramakrishnan N, Srinivas M, Ramarao P
(Received 15 July 1998; accepted 16 February 1999)

Abstract
The stretch zone width (SZW = 1/2 CTOD, the crack tip opening displacement) method for determining J_IC involves fewer specimens and lesser size restrictions compared to the conventional J-R curve method. However, the accuracy of the SZW-based procedure depends on each term of the J-CTOD relationship, i.e., J_IC = m · s · CTOD_C. This paper presents a numerical investigation of the J-CTOD relationship, which has been carried out using a large-deformation finite element method (FEM). The slope of the blunting line (m) is computed for various combinations of yield strength-to-elastic modulus ratio (s_o/E), power law strain-hardening exponent (n), and different measures of stress (s in the J-CTOD relationship). This work brings out the importance of the correct choice of the stress measure. Also, an effective CTOD approach is numerically validated where a sharp fatigue precrack of fracture specimens can be substituted by one with a finite notch root radius without loss of accuracy in J_IC.

Keywords:
blunting line, crack tip opening, finite element, notch root radius, stretch zone, stretch zone width, zone width method

Paper ID: JTE27308

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Author Suresh RKV, Ramakrishnan N, Srinivas M, Ramarao P Title On the determination of JIC using the stretch zone width method Symposium , Committee: on