Abstract: In the paper an alternative formulation of the RKR local fracture criterion is proposed. It is based on the features of the stress distribution in front of a blunted crack in an elastic-plastic material. The stress distribution is computed using the finite strain option in the finite element method. It is postulated that the opening stress in front of the crack should be greater than the critical one, σ c , over the distance l⩾l c , where l c is considered as a material parameter. The hypothesis is applied to estimate the influence of the in-plane constraint on fracture toughness. New formulas to compute the critical value of the J-integral are derived both for the small scale yielding and large plastic deformations in front of the crack. The results obtained are compared with the Sumpter and Forbes experimental results and with the O'Dowd analytical formula concerning the J c =J c (J IC ,Q) relation.
B I B L I O G R A F I A1. Ritchie, R.O.& Knott, J.F.& Rice, J.R., "On the Relationship Between Tensile Stress and Fracture Toughness in Mild Steels", J Mech Phys Solid, vol. 21, 1973, p.395-410
2. Hutchinson, J.W., "Singular behaviour at the end of a tensile crack in a hardening material", J Mech Phys Solid, vol. 16, 1968, p.13-31
3. Rice, J.R.& Rosengren, G.F., "Plane strain deformation near a crack tip in a power-law hardening material", J Mech Phys Solid, vol. 16, 1968, p.1-12
4. Needleman, A.& Tvergaard, V., "An analysis of ductile rapture modes of a crack tip", J Mech Phys Solid, vol. 35, 1987, p.151-183
5. Shih CF, Xia L. Modeling crack growth resistance using computational cells with microstructurally-based length scales, In: Mark Kirk, Ad Bakker, editors. Constraint effects in fracture theory and applications, vol. 2. ASTM STP 1244, 1995. p. 163-90.
6. Bordet, S.R.& Karstensen, A.D.& Knowles, D.M.& Wiesner, C.S., "A new statistical local criterion for cleavage fracture in steel. Part I: model presentation", Engng Fract Mech, vol. 72, 2005, p.435-452, Part II: application to an offshore structural steel, p. 453-74
7. O'Dowd, N.P., "Applications of two parameter approaches in elastic-plastic fracture mechanics", Engng Fract Mech, vol. 52, 3, 1995, p.445-446
8. Beremin N. A local criterion for cleavage fracture of a nuclear pressure vessel steel, Met. Transaction A, 14A, p. 2277-87.
9. Gao, X.& Dodds, R.H., "An engineering approach to assess constraint effects on cleavage fracture toughness", Engng Fract Mech, vol. 68, 2001, p.263-283
10. Chao Y, Ji W, Cleavage fracture quantified, In: Mark Kirk, Ad Bakker, editors. Constraint effects in fracture theory and applications, vol. 2, ASTM STP 1244, 1995. p. 9-20.
11. Neimitz, A.& Galkiewicz, J., "Fracture toughness of structural components. The influence of constraint", Int J Pres Ves Pip, vol. 83, 2006, p.42-54
12. Yu, S.R.& Yan, Z.G.& Cao, R.& Chen, J.H., "On the change of fracture mechanism with test temperature", Engng Fract Mech, vol. 73, 2006, p.331-347
13. O'Dowd, N.P.& Shih, C.F., "Family of crack-tip fields characterised by a triaxiality parameter-I. Structure of fields", J Mech Phys Solid, vol. 39, 1991, p.898-1015
14. O'Dowd, N.P.& Shih, C.F., "Family of crack-tip fields characterised by a triaxiality parameter-II. Fracture applications", J Mech Phys Solid, vol. 40, 1992, p.939-963
15. Sumpter JGD, Forbes AT. Constraint based analysis of shallow cracks in mild steels, In: Proceedings of TWI/EWI/IS international conference on shallow crack fracture mechanics, toughness tests and applications, 1992, Paper 7, Cambridge UK. 
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