SEDL / STP / STP1244-EB / STP14645S

A Comparison of J and CTOD as Elastic-Plastic Fracture Characterizing Parameters

Gordon, JR
Director, Edison Welding Institute, Columbus, OH

Neale, BK
Research Officer, Nuclear Electric, CEGB, Berkeley Nuclear Laboratories, Berkeley, Gloucester

Wang, Y-Y
Senior Research Engineer, Edison Welding Institute, Columbus, OH

Pages: 20    Published: Jan 1995

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Abstract

This paper presents results of experimental and numerical analysis studies to investigate the relationship between J and CTOD and assess whether they are, indeed, both suitable elastic-plastic fracture characterizing parameters. Detailed elastic-plastic finite element analyses were undertaken for SE(B) specimens with a/W ratios of 0.1, 0.2, 0.3 and 0.5. Analyses were performed for a range of material stress-strain curves and yield strength levels to determine the influence of work hardening and yield strength on the J-CTOD relationship.

It was found that: 1. The standard CTOD estimation procedure can give rise to significant errors in the predicted CTOD for high work hardening materials (σ^TS/σ^YS > 1.5) .2. For SE(B) specimens, the following J-CTOD correlation can be used to relate J to CTOD J=mTSσTSCTOD where m^TS = 1.21 + 0.95 (a/W) − 0.5 (a/W)². 3. J and CTOD do not always produce consistent trends when used to characterize the fracture toughness of different materials, i.e., the toughness ranking based on J is not necessarily the same as the ranking obtained using CTOD.