Assessment of the service life of notched A36 steel, comparing results from experimental methods with predictions from theoretical damage models

A36 steel, also known as S235JR in Europe or ASTM A36 in the United States, is widely used in metal structures due to its good mechanical properties, durability, and weldability. However, one of the major challenges associated with its use lies in predicting service life, particularly in the face of fatigue and progressive damage. It is therefore essential for designers and operators to better anticipate the onset of defects and assess damage progression to ensure structural reliability and safety.

This work aims to estimate the service life of A36 steel through an approach combining experimental tests and theoretical modeling. Fatigue tests were conducted on notched specimens, followed by static tensile tests to measure the reduction in residual ultimate stress. The experimental results allowed us to plot the Wöhler curve (S-N) and determine the constants associated with the Erisman damage law. Subsequently, the Mesmacque law was used to model damage evolution as a function of the fraction of life consumed, taking into account the loading sequence effect.

A comparison between the experimental results and the predictions provided by the analytical models was performed to assess their accuracy and their ability to represent the actual behavior of the material. This study identifies the most appropriate approaches to improve preventive maintenance strategies for A36 steel structures.