Extraction of Johnson–Cook model constants for API-5L steel and their evaluation in finite element modeling

Document Type : Research Article

Authors

1 Mechanical Engineering department, faculty of engineering, kermanshah university of technology, kermanshah, iran

2 Department of Mechanical Engineering, faculty of engineering, Kermanshah University of Technology, Kermanshah, Iran

Abstract

API-5L steel pipelines are vital components in oil and gas industries, subjected to complex mechanical and environmental loadings, and predicting the mechanical behavior and failure mechanisms of these steels requires advanced models. In this research, the Johnson-Cook model, as one of the most widely used elastoplastic and failure models, has been calibrated and evaluated for API-5L steel. To extract experimental data, uniaxial tensile tests were performed on standard and notched specimens with various radii. The results revealed true stress-strain, elastic-plastic behavior of the material, and fracture strain under different levels of stress triaxiality. The results showed that increasing stress triaxiality causes an exponential decrease in fracture strain, and strain concentration and damage in specimens with smaller notches begin near the notch root. For model validation, three-dimensional finite element simulations were conducted. Comparison of results showed that the Johnson-Cook model is capable of accurately reproducing the force-displacement curve and predicting the maximum load with an error of 1 to 3 percent, although a larger discrepancy was observed in predicting fracture displacement, which is due to the inherent limitations of the model in specific geometric conditions. This study demonstrates that precise calibration of the Johnson-Cook model based on experimental data provides an efficient tool for simulating and predicting failure in API-5L tubular steels and can be used in design analyses and safety assessments of energy transmission lines.

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Amirkabir Journal of Mechanical Engineering
Volume 57, Issue 8
November 2025
Pages 1069-1084

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