TWI Industrial Member Report Summary 724/2001
W Xu, S D Smith and R H Leggatt
Assessment of the acceptability of flaws in metallic structures must consider effects of secondary stresses such as welding residual stresses. The R6/BS 7910 fracture assessment approaches implement an effective shift in the FAD by the so-called ?-factor to allow for the effects. The detailed procedures for calculating the ?-factor are set out in the literature. The scheme provides an analytical solution to a complicated problem, but the ?-factor approach is somewhat difficult to grasp intuitively and validations of the method were limited at the time when it was introduced. An extensive validation study carried out later using the finite element method revealed that the original ?-factor was not safe for small cracks in a yield magnitude welding residual stress field, although modifications have been introduced to the approach more recently.
- To provide a full background of the V-factor and its relation to the ?-factor
- To provide a method for calculating the V-factor from finite element analysis
- To provide a validation of the V-factor using the finite element method