Session: CS-23-01 Improvement of Flaw Assessment Procedures in Fitness-for-Service Codes

Paper Number: 122801

122801 - Assessment of Circumferential Crack-Like Flaws in Piping Accounting for Partial Compressive Zone Using Contact Elements 

When a circumferential surface crack-like flaw is detected in a pipe subjected to a bending load, it may be partially located in a compressive zone, preventing the crack faces to open locally. In order to take that phenomenon into account, contact elements at crack faces should be used in numerical Fracture Mechanics analyses to avoid crack face interpenetration. However, usual Fracture Mechanics analyses do not consider such contact at crack faces as the non-linearity introduced in the system resolution leads to excessive computation time for industrial applications. Consequently, interpenetration of the crack faces occurs which is not realistic. This behavior is observed when the Crack Tip Opening Displacement (CTOD) or the mode-I Stress Intensity Factor (SIF) have negative values along the crack front.

In the present work, Fracture Mechanics simulations are conducted to assess the impact of including contact conditions at crack faces on mode I, II and III SIF considering linear elastic material behavior. Then, the behavior of the crack faces with respect to increasing load is assessed through J-integral calculations considering elastic-plastic material behavior. Those results along the crack front in the tensile zone are assessed for different cracks and load combinations. All these analyses intend to draw up a statement about the necessity to model contact conditions at crack faces in flaw acceptability assessments.

Presenting Author: Pierre Dulieu Tractebel

Presenting Author Biography: Pierre Dulieu is Mechanical Engineer from University of Louvain (Belgium). He is Principal Engineer at Tractebel and Expert in Fracture Mechanics as well as in numerical simulation by XFEM. For PVP-2024 conference, he is TPR of the Codes & Standards topic.

Authors:

Pierre Dulieu Tractebel
Antoine Van Ende Tractebel
Valéry Lacroix Tractebel