VCE Method of J Determination for a Pressurized Pipe Under Bending

Abstract

The J values for a circumferential through crack in a 4-in. (101.6-mm) schedule 80 pipe subjected to axial and bending loads were determined. The Virtual Crack Extension (VCE) method was used to compute J values. The VCE calculated J values are then compared with those obtained by the differential potential energy method and a simplified fracture analysis method. Good comparisons are observed between the results obtained from all of these three methods up to a load level well above the first yield. Advantages of using VCE method are discussed. Experimental results are presented for an identical pipe, made of 304 wrought stainless steel, containing a circumferential through-wall crack and subjected to internal pressure and external bending moment. The VCE method is used to obtain the load versus J relationship from which the initiation load is estimated using the J initiation value obtained from compact tension specimens. This value is then compared to the initiation load determined by acoustic emission measurements. These two results agree within the estimated experimental scatter.