Analytical Method for Damage Reliability Assessment of Steel

A36 steel also known as S235JR in Europe or ASTM A36 in the United States is a very common material in steel structures. It is widely used because it is strong, durable, and easy to weld. But one of the major challenges when working with it is monitoring the progression of fatigue damage.

In this study, we sought to estimate the service life of A36 steel. To do so, we conducted fatigue tests on notched specimens, followed by static tensile tests to observe how the residual ultimate stress decreased. This allowed us to track the progression of damage using Erisman’s law and to analyze the Wöhler curve (S-N curve). The experimental results helped us determine the constants associated with this curve. Next, based on this curve, we evaluated the damage using a model based on the damaged stress model.

Next, we'll conduct a reliability study. We'll use the stress-strain method. The idea is to analyze the degradation of the ultimate residual stress as a function of the life fraction. This will allow us to determine that fraction and compare it to the results we already have.

Finally, we compared the critical life fractions obtained using the two laws to identify the one that enables effective predictive maintenance.