Numerical investigation of residual ultimate strength of dented metallic pipes subjected to pure bending

Abstract

A dent is one of the main structural damages that may affect ultimate strength. In this paper, the residual ultimate strength of dented metallic pipes subjected to a bending moment is quantitatively investigated. The numerical model is developed accounting for the variation of the dent length (l d ), dent depth (d d ), dent width (w d ), dent rotation angle (θ d ) and dent location based on ABAQUS Python. The numerical model is validated by test results from a four-point bending test. Subsequently, a parametric investigation is performed on the effects of wave-type initial imperfection, D/t and dent geometrical parameters. It is found that both l d and d d have a significant effect on the residual ultimate strength of dented metallic pipes, while the effect of w d is slight. Finally, an empirical formula with respect to l d and d d has been proposed for the prediction of bending moment, which can be deployed for practical purposes.Nomenclature κ the curvature of pipe (1/m) κ 0 the referential curvature of pipe (1/m) κ cr the critical curvature of pipe (1/m) λ l normalised dent length λ w normalised dent width λ cl critical half-wavelength ω dent depth variation (mm) σ u material ultimate tensile strength (MPa) σ y material yielding strength (MPa) σ 11 stress component in pipe axial direction (MPa) σ 22 stress component in pipe hoop direction (MPa) σ eng engineering stress of material (MPa

Residual ultimate strength of seamless metallic pipelines under a bending moment-a numerical investigation

“…The value of curvature diagrams with the variation of the dent depth, length and width. Compared with the intact pipe, it is found that the occurrence of a particular dent affects its strength, Furthermore, as obtained from the former research by Cai et al (2018a), it is also observed from 485 Fig. 15 that both the dent depth (d d ) and length (l d ) have a considerable influence on the bending behavior, decreasing both the ultimate bending moment and critical curvature significantly.…”

“…6. Here, the dented region has not been specially partitioned as in the former research (Cai et al, 2018a), instead, a general refined mesh strategy is assigned in this region. The mesh is largely refined in the damaged region in order to avoid the artificial bending moment, with the minimum mesh equal to 2 mm, i.e.…”

“…Artificial damage such as a dent, metal loss, a crack and their combinations thereof is properly introduced on specimens. Meanwhile, an initial numerical investigation on the dented pipes has been performed based on a simplified FEM model from the former research of the authors Cai et al (2018a). However, some influential factors such as the real boundary effect, and the frictions from the test configuration have not been accounted for due to simplifications.…”

Experimental Investigation of Residual Ultimate Strength of Damaged Metallic Pipelines

“…It should be noted that quantification of damage effect cannot be done due to the limited number of specimens in the test. Other research is needed, as seen in the published papers by the authors [36,37].…”

Residual ultimate strength of damaged seamless metallic pipelines with combined dent and metal loss

“…In the former research of the authors [1][2][3], a four-point bending test has been successfully carried out on metallic seamless pipes with different types of structural damage. Influential parameters such as materials, test boundaries and initial imperfections have been identified.…”