Numerical assessment of the high cycle fatigue behavior of high strength steels affected by shear-cutting operations

Shear-cutting processes are arguably among the most preferred technologies for performing material removal operations in the manufacturing of chassis components due to the combination of high production rate and cost-efficiency. Nevertheless, they may severely jeopardize the fatigue response of high strength metals, compromising the current trend of using this class of materials for weight reduction of automotive chassis parts. Thus, the generation of reliable data featuring the influence of these operations on the material fatigue behavior is essential to further support this lightweighting tendency. Commonly employed for this aim, traditional fatigue tests are usually time-consuming and rather expensive. In this context, numerical simulations arise as a viable alternative, providing not only material-related information but also assisting engineers in the design of new components. In this work, an isotropic damage-based high cycle fatigue model is employed to estimate the fatigue life of trimmed and punched specimens of two complex phase steels. The residual stresses obtained from each process simulation and the roughness measured on the cut surface are included in the model to account for the influence of these operations on the material fatigue strength. Furthermore, standard uniaxial tensile properties and S–N data resulting from fatigue tests on as-polished specimens are the only material information required. A good agreement is found between the numerical fatigue life predictions and the experimental measurements, remaining below an error factor of three for all the estimated cases. In addition to coupon specimens, the model is also readily extensible to component-level applications, enabling the fatigue assessment of metallic engineering structures featuring shear-cut surfaces.