An investigation on the circumferential surface crack growth in steel pipes subjected to fatigue bending. (February 2020)

• Record Type: Journal Article
• Authors: Li, Zongchen; Jiang, Xiaoli; Hopman, Hans; Zhu, Ling; Liu, Zhiping
• Is Part Of: Theoretical and applied fracture mechanics. Volume 105(2020)
• Publication Date: 2020-02
• Subjects: Steel pipes -- Circumferential surface crack -- Surface crack growth rate -- Analytical method -- Structural integrity; Fracture mechanics -- Periodicals; 620.1126
• DOI: 10.1016/j.tafmec.2019.102403
• Languages: English
• ISSNs: 0167-8442

Abstract

Highlights: Propose an analytical method to evaluate SIF of surface cracked pipe under bending. For this purpose, finite element analysis and fatigue tests are implemented. The method introduces new correction factors in terms of load and geometry effects. It predicts SIF more accurately than conventional analytical methods. Abstract: In the present paper, we propose an analytical method to calculate the Stress Intensity Factor (SIF) of circumferential surface cracks in steel pipes subjected to bending. In light of pipe geometry and bending load case, the analytical formula is raised by introducing new bending correction factors and new geometry correction factors on the basis of the Newman-Raju's method. The bending correction factors are deduced based on the bending stress gradient, while the geometry correction factors are determined by parametric studies for internal surface cracks and external surface cracks respectively. Owing to a large data set requirement by the parametric studies, three-dimensional finite element (FE) models of evaluating SIFs of circumferential surface cracks are developed. The FE method is validated to ensure that it could provide accurate SIF estimations. Analytical verification is conducted which shows that the SIF evaluated by the proposed analytical method match well with the results evaluated by the recommended analytical method. Then experimental investigations of external surface crack growth in offshore steel pipe subjected to fatigue bending are implemented to further validate the analytical method of predicting surface crack growth rate. The analytical results match well with the test results and the available experimental data from literature, indicating that the analytical method can be used for practical purposes and facilitate the crack growth evaluation and residual fatigue life prediction of cracked steel pipes.