Abstract
This research presents the numerical evaluation of fatigue crack growth of structural steels S355 and S960 based on Paris’ law parameters (C and m) that are experimentally determined with a single edge notched tension (SENT) specimen using optical and crack gauge measurements on an electromotive resonance machine at constant amplitude load. The sustainable technique is replacing destructive, time-consuming and expensive approaches in structural integrity. The crack propagation is modelled using the 3D finite element method (FEM) with adaptive remeshing of tetrahedral elements along with the crack initiator elements provided in simulation software for crack propagation based on linear elastic fracture mechanics (LEFM). The stress intensity is computed based on the evaluation of energy release rates according to Irwin’s crack closure integral with applied cyclic load of 62.5 MPa, 100 MPa and 150 MPa and stress ratios of R = 0 and 0.1. In order to achieve optimized mesh size towards load cycle and computational time, mesh and re-mesh sensitivity analysis is conducted. The results indicate that the virtual crack closure technique VCCT-based 3D FEM shows acceptable agreement compared to the experimental investigation with the percentage error up to 7.9% for S355 and 12.8% for S960 structural steel.
Highlights
High-strength low-alloy (HSLA) structural steel keeps increasing remarkably due to its equivalent weight to strength ratio to meet specific structural strength, in machinery and offshore industries where fatigue loading is prevalent
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The virtual crack closure technique (VCCT) can explain this increase in fatigue crack propagation rate using the similarity concept. These results indicate that the adaptive remeshing strategy with VCCT in MSC Marc/Mentat is capable of the conservative prediction of fatigue crack propagation
Summary
High-strength low-alloy (HSLA) structural steel keeps increasing remarkably due to its equivalent weight to strength ratio to meet specific structural strength, in machinery and offshore industries where fatigue loading is prevalent. The failure in steel structure subjected to cyclic loading often arise from surface defect induced by manufacturing processes that could nucleate crack. Several studies of test data obtained for steel and a few other materials require a comprehensive material parameter that affects crack growth [1–3]. Many factors influence fatigue crack growth (FCG) in structures, the stress intensity factor (SIF) in the crack front is a significant parameter in the prediction analysis using linear elastic fracture mechanics (LEFM). The Griffith theory allows for a limited amount of plasticity at the crack tip as the energy release rate (G) leads to the same results as the SIF in linear elastic condition proposed by Irwin in steel [4]
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