A new approach for correlating Paris parameters with fatigue life of aircraft fuselage panels

Abstract

This work presents a numerical technique that establishes a relationship between the C and m parameters of the Paris Law and the number of fatigue life cycles. This relationship is particularly important for determining the material's ability to withstand a specified number of cycles in an aircraft fuselage design. The methodology is based on a multiscale problem and comprises two stages: the macro model, which focuses on internal stresses and critical point location, and the micro model, which considers the critical fatigue life cycle number (n) across a "grid" of C and m parameters, resulting in the optimal curve N(C,m). To validate the adopted methodology, the academic program BemCracker2D has been used to calculate the internal stress fields, simulate cracks, and estimate fatigue life. Three case studies were conducted, and the results indicated that the range of C and m values obtained depends on the configuration of the macro model, the physical parameters of the material, and the defined number of cycles in the design. Ultimately, this computational technique allows for generalization to any fuselage damage analysis model, providing C and m Paris parameter data to mitigate fatigue damage.