Cl. Lau et al., METHODOLOGIES FOR PREDICTING J-INTEGRALS UNDER LARGE PLASTIC-DEFORMATION .1. FURTHER DEVELOPMENTS FOR TENSION LOADING, Engineering fracture mechanics, 49(3), 1994, pp. 337-354
Based on the results of a parametric finite element study on single ed
ge notch specimens with shallow crack geometries (0.05 less than or eq
ual to a/W less than or equal to 0.01) under large plastic deformation
, a revised J-estimation method is presented. The revised scheme focus
ed on material laws which can be approximated by a power law represent
ation. the scheme uses the format of an existing method which adopts T
urner's EnJ tripartite approach of J-estimation: Linear Elastic Fractu
re Mechanics, Net Section Yield and Gross Section Yield. The for of th
e J vs strain relationship in the gross section yield region was deriv
ed from a consideration of the HRR strain field equation, the EPRI pla
stic J equation and the definition of J in terms of the energy release
rate. Comparison with finite element results shows that the revised s
cheme generally provides safe predictions of the crack driving paramet
er. For low to medium work hardening materials (power law exponent n g
reater than or equal to 5), the accuracy of prediction is within about
5%. The scheme has also been shown to be equally applicable to centre
cracked panels with short cracks.