O. Ranestad et al., 2-PARAMETER (J-M) DESCRIPTION OF CRACK-TIP STRESS-FIELDS FOR AN IDEALIZED WELDMENT IN SMALL-SCALE YIELDING, International journal of fracture, 88(4), 1998, pp. 315-333
The crack tip stress-field in a trimaterial finite element model has b
een examined. The model represents an idealised steel weldment with a
crack located at the fusion line. The model was loaded with a KI displ
acement field to simulate small scale yielding conditions. The effect
of changing the weld metal plastic properties and the HAZ layer thickn
ess on the crack tip stress-field was studied, keeping the material pr
operties of the HAZ and base metal constant. The results show that the
calculated J-integral remains path independent in the trimaterial mod
el. It is confirmed that the crack tip stress-fields can be normalised
by the J-integral. The mismatch constraint can be characterised by a
difference field, which is independent of the normalised distance from
the crack tip. The results show that changes of HAZ thickness only ha
ve a small effect on the stress-fields close to the crack tip. The har
denability of the weld metal influences on the slope of the crack tip
stress distribution, but for small changes in hardenability, this effe
ct can be neglected. The results indicate that the difference fields s
how some radial dependence when a homogeneous reference field is used,
but the radial dependence was removed by introducing an inhomogeneous
reference field. The effect of changes in the weld metal yield streng
th has been described with a two parameter (J-M) formulation using the
inhomogeneous reference field.