C. Ruggieri et al., Transferability of elastic-plastic fracture toughness using the Weibull stress approach: significance of parameter calibration, ENG FRACT M, 67(2), 2000, pp. 101-117
This study focuses on the Weibull stress approach to assess the effects of
constraint loss on cleavage fracture toughness (J(c)). The investigation ad
dresses the significance of the Weibull modulus m (which bears direct conne
ction with parameter calibration schemes) on the correlation of macroscopic
fracture toughness for varying crack configurations. In particular, we que
stion the ability of current calibration procedures to provide reliable val
ues for the Weibull parameters (m, sigma(u)) and present arguments that a n
on-uniqueness arises in the calibrated values, i.e., many pairs of (m, sigm
a(u)) provide equally good correlation of critical Weibull stress values wi
th the distribution of measured fracture toughness values. Our analyses als
o show a strong sensitivity of corrected J(c)-values (LSY --> SSY constrain
t correction) on parameter m for several specimen geometries and different
material flow properties: such results provide compelling support to introd
uce an alternative, improved calibration procedure based on a toughness sca
ling model. Results of a parameter study suggest typical values of m for a
wide range of material flow properties and toughness values. An example ill
ustrates application of the toughness scaling model to construct Weibull st
ress based, constraint corrections for measured J(c)-values to provide the
Weibull modulus, m, for a structural C-Mn steel (BS 4360 Gr 50D). (C) 2000
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