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Due to the humid climate in Taiwan area, the underground pipes are prone to be damaged by corrosion, which could be more severe for the environment with high salinity near the coast. In addition, the situation could be worse where the underground pipeline planning was not enforced. For example, a water pipe or a sewage pipe may be too close to a pressurized pipe, which could be corroded if the water pipe or the sewage pipe leaked. In this study, the numerical simulation software ABAQUS was used to simulate underground pipelines damaged by corrosion. The stress and displacement behavior was analyzed for scenarios with different internal pressure and surface loading conditions. In addition, the performance of the cured-in-place-pipe (CIPP) method, a trenchless rehabilitation method was also numerically analyzed. The results suggest that it can reinforce the damaged pipe by reducing the stress concentration and reducing the differential displacement. However, the design of the CIPP liner could be further optimized in terms of its design thickness. [ABSTRACT FROM AUTHOR]

A multi-scale modeling approach for simulating the tensile behavior of the corroded aluminum alloy 2024 T3 was developed, accounting for both the geometrical features of corrosion damage and the effect of corrosion-induced hydrogen embrittlement (HE). The approach combines two Finite Element (FE) models: a model of a three-dimensional Representative Unit Cell (RUC), representing an exfoliated area and its correspondent hydrogen embrittled zone (HEZ), and a model of the tensile specimen. The models lie at the micro- and macro-scales, respectively. The characteristics of the HEZ are determined from measurements of nanoindentation hardness, conducted on pre-corroded specimens. Using the model of the RUC, the local homogenized mechanical behavior of the corroded material is simulated. Then, the behavior of the exfoliated areas is assigned into different areas (elements) of the tensile specimen and final analyses are performed to simulate the tensile behavior of the corroded material. The approach was applied to model specimens after 8, 16 and 24 h exposure periods of the Exfoliation Corrosion (EXCO) test. For validation of the approach, tensile tests were used. The numerical results show that this approach is suitable for accurately simulating the tensile behavior of pre-corroded experimental specimens, accounting for both geometrical features of corrosion damage and corrosion-induced HE.

Purpose – The purpose of this paper is to develop a multi-scale modeling approach for simulating the tensile behavior of corroded aluminum alloy 2024 T3. Design/methodology/approach – The approach combines two FE models: a model of a three-dimensional representative unit cell representing a pit and a model of the tensile specimen. The models lie at the micro- and macro-scales, respectively. The local homogenized mechanical behavior of the corroded material is simulated for different pit configurations. Then, the behavior of the pits is introduced into different areas (elements) of the tensile specimen and final analyses are performed to simulate the mechanical behavior of the corroded material. The approach has been applied to six different exposure periods of the exfoliation corrosion test. Findings – The numerical results show that the presence of pits and exfoliated areas reduces the yield strength of the material. The comparison of predicted elongation to fracture with the experimental of each exposure period value allows for the indirect assessment of the effect of hydrogen embrittlement. Originality/value – Since the characteristics of corrosion damage evolution with exposure time are constant for the specific material, the model could be applied for the simulation of the mechanical behavior of any corroded structural part (e.g. a mechanically fastened panel) made from the aluminum 2024 T3 alloy. [ABSTRACT FROM AUTHOR]

A modification of a method for the determination of limiting pressure for gas and oil pipelines with corrosion damages of local type under the action of internal pressure and with allowance for temperature field is considered. The problem is solved numerically in three-dimensional formulation. Particular numerical examples illustrate the general design procedure and show satisfactory agreement with experiment. [ABSTRACT FROM AUTHOR]

A method of determination of the limiting pressure for gas and oil pipelines susceptible to local corrosion is discussed. The proposed method is based on a combined use of strength criteria of the continuum mechanics and fracture mechanics. Its applicability is verified by the results of numerical studies and laboratory model tests. [ABSTRACT FROM AUTHOR]

In this paper, we consider the inverse problem for the Laplace equation in two-dimensions which requires the determination of the location, size and shape of an unknown, or partially unknown, portion γ ⊂ ∂ Ω of the boundary ∂ Ω of a solution domain Ω ⊂ R 2 from additional Cauchy data on the remaining portion of the boundary Γ = ∂ Ω - γ. This problem arises in the study of quantitative non-destructive evaluation of corrosion in materials in which boundary measurements of currents and voltages are used to determine the material loss caused by corrosion. This inverse problem is approached using the boundary element method (BEM) in conjunction with the Tikhonov first-order regularization procedure. The choice of the regularization parameter is based on an L-curve type criterion although, alternatively one may use the discrepancy principle. Several examples which involve noisy Cauchy input data are thoroughly investigated showing that the numerical method produces a stable approximate solution which is also convergent to the exact solution as the data errors tend to zero. [ABSTRACT FROM AUTHOR]