Simulation of Crack Propagation in API 5L X52 Pressurized Pipes Using XFEM-Based Cohesive Segment Approach

Analysis of Crack Behaviour in Pipeline System Using FAD Diagram Based on Numerical Simulation under XFEM

“…To make a good calculation, the dimensions of the elements through the thickness of the wall (i.e., the path of propagation) is 0.1 mm, although the rest of the structure was meshed with coarser elements. For this study, crack propagation modelling is carried out by combining the XFEM method and cohesive segments approach [44], where this technique has been most recently employed [45,46]. This method was based on the traction separation law.…”

Prediction of Tensile Strain Capacity for X52 Steel Pipeline Materials Using the Extended Finite Element Method

“…The solid part was meshed with an 8-node linear brick element with reduced integration and hourglass control (C3D8R) as well. Based on mesh convergence analysis performed by Lin et al [13], a finer mesh (0.5 mm) was used in the partitioned zone near the crack propagation path and a coarser mesh (5 mm) was used in the area far from the crack to guarantee the accuracy of calculation, as displayed in Figure 2. The mesh construction in the solid part was generated with a mesh size between 0.5 and 5 mm.…”

“…Maxpe is chosen as the damage criterion. In contrast to Maxps, which was used previously by Lin et al [13] to predict the fracture response of this grade of vintage pipeline, Maxpe critical values are relatable to the physical critical strain values expected in the vicinity of the crack tip [12]. The crack initiation and propagation are numerically predicted through simulating eight published full-scale tests of X52 vintage pipes that are subjected to the combination of internal pressure and external eccentric tension which were reported by Abdulhameed et al [21].…”

“…The finite element method (FEM) is a cost-efficient technique for analyzing pipelines under such loading conditions. The cohesive zone model (CZM) is the applicable numerical tool in FEM used in simulating the propagation of a crack [13]. In CZM, the stress singularity corresponding to linear elastic fracture mechanics at the crack tips is avoided.…”

“…Ameli et al [16] used XFEM to obtain the fracture parameters, maximum principal stress (Maxps) = 1400 MPa for damage initiation and G c = 200 N/mm for damage evolution, by simulating the single-edge notch tension (SENT) test of X42 vintage pipelines. Similarly, Lin et al [13] obtained the XFEM set of damage parameters, Maxps = 750 MPa and G c = 900 N/mm, by simulating the reported eight full-scale tests of an X52 vintage pipe subjected to internal pressure, external tensile stress, and bending. However, the use of a stress-based damage initiation in XFEM is a bit problematic; both Ameli's and Lin's simulations reported a maximum principal stress that is higher than the ultimate stress of the material, implying that such damage criterion is impractical and probably not applicable to modeling damage in materials subjected to plastifying crack tips.…”