Dpg. Lidbury et al., PREDICTION OF THE FIRST SPINNING CYLINDER TEST USING CONTINUUM DAMAGEMECHANICS, Nuclear Engineering and Design, 152(1-3), 1994, pp. 1-10
For many years large-scale experiments have been performed world-wide
to validate aspects of fracture mechanics methodology. Special emphasi
s has been given to correlations between small- and large-scale specim
en behaviour in quantifying the structural behaviour of pressure vesse
ls, piping and closures. Within this context, the first three spinning
cylinder tests, performed by AEA Technology at its Risley Laboratory,
addressed the phenomenon of stable crack growth by ductile tearing in
contained yield and conditions simulating pressurized thermal shock l
oading in a PWR reactor pressure vessel. A notable feature of the test
data was that the effective resistance to crack growth, as measured i
n terms of the J R-curve, was appreciably greater than that anticipate
d from small-scale testing, both at initiation and after small amounts
(a few millimetres) of tearing. In the present paper, two independent
finite element analyses of the first-spinning cylinder test (SC 1) ar
e presented and compared. Both involved application of the Rousselier
ductile damage theory in an attempt to understand better the transfera
bility of test data from small specimens to structural validation test
s. In each instance, the parameters associated with the theory's const
itutive equation were calibrated in terms of data from notched-tensile
and (or) fracture mechanics tests, metallographic observations and (o
r) chemical composition. The evolution of ductile damage local to the
crack tip during SC 1 was thereby calculated and, together with a crac
k growth criterion based on the maximisation of opening-mode stress, u
sed as the basis for predicting cylinder R-curves (angular velocity vs
. Delta a, J integral vs. Delta a). Except in the initiation region, t
he results show the Rousselier model to be capable of predicting corre
ctly the enhancement of tearing toughness of the cylinder relative to
that of conventional test specimens, given an appropriate choice of fi
nite element cell size in the region representing the crack tip. As su
ch, they represent a positive step towards achieving the goal to estab
lish continuum damage mechanics as a reliable predictive engineering t
ool.