8 ues(i.e., increasing the Weibull modulus, §). Such features most likely impose a stronger sensitivity of the prediction process on the calibratedm-value. CONCLUDING REMARKS This paper describes a new procedure to calibrate the Weibull stress modulus, m, which employs SSY values for cleavage fracture toughness measured in the DBT region. The calibration scheme utilizes only one set of fracture toughness data while, at the same time, avoiding the non-uniqueness of calibrated Weibull stress parameters. A thickness correction based upon the weakest link model (WLM) provides the second toughness parameter required in the calibration scheme. The proposed methodology predicts the measured statistical distribution of cleavage fracture toughness (Jc) for different fracture specimens which provides a compelling support to the new calibration procedure. Acknowledgements This investigation is supported by the Scientific Foundation of the State of São Paulo (FAPESP) through Grant 01/06919-9 and by the Brazilian Scientific Council for Research and Technology (CNPq) through Grant 300048. The author is indebted to Prof. Robert H. Dodds (University of Illinois) for many valuable discussions. References 1. Ruggieri, C. and Dodds, R. H., Int. J. Fracture, Vol. 79, pp. 309-340, 1996. 2. Gao,X., Ruggieri, C. and Dodds, R. H., Int. J. Fracture, Vol. 92, pp. 175ï200, 1998. 3. Ruggieri, C., Gao,X. and Dodds, R. H., Engng. Fracture Mech., Vol. 67, pp. 101ï117, 2000. 4. Beremin, F. M., Metall. Trans., Vol. 14A, pp. 2277ï2287, 1983. 5. Wallin, K., Engng. Fracture Mech., Vol. 19, pp. 1085ï1093, 1984. 6. Ruggieri, C., BTïPNVï51(Technical Report), EPUSP, University of São Paulo, 2001. 7. Gao,X., Dodds, R. H., Tregoning, R. L., Joyce, J. A. and Link, R. E., Fatigue Fract. Engng. Mater. Struct., Vol. 22, pp. 481ï493, 1999. 8. Mann, N. R., Schafer, R. E. and Singpurwalla, N. D., Methods for Statistical Analysis of Reliability and Life Data, Jonh Wiley & Sons, New York, 1974. 9. Minami, F., BrücknerïFoit, A., Munz, D.and Trolldenier, B., Int. J. Fracture, Vol. 54, pp. 197ï210, 1992. 10. Koppenhoefer, K., Gullerud, A., Ruggieri, C., Dodds, R. and Healy, B., Structural Research Series (SRS) 596,UILUïENGï94ï2017,University of Illinois at UrbanaïChampaign, 1994. 11. Joyce, J. A. and Link, R. E., inFatigue and Fracture Mechanics: 28th Volume, ASTM STP 1321, J. H. Underwood, et al. Eds., American Society for Testing and Materials, Philadelphia, pp. 243ï262, 1997. 12. Tregoning, R., Unpublished Experimental Data, 1998. 13. Ruggieri, C., Int. J. Fracture, Vol. 110, pp. 281ï304, 2001. 14. American Society for Testing and Materials, ASTM E-1921, Philadelphia, 1998. 15. Ruggieri, C. Engng. Fracture Mech., Submmitted for publication.
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