Fatigue life prediction on steel plates under variable range stress from 2D FEM models

Resumo

Structural and component metallic materials usually undergo strict quality control at the manufacturing
stage. However, they are inevitably subject to non-homogeneity and, consequently, to crack nucleation under
fatigue loads. Fatigue failures occur in a wide sort of engineering applications, such as platforms, bridges, ships,
and aircraft. These structures are constantly being subjected to variable amplitude loadings. Therefore, increasing
demands arise for studies to better understand the phenomenon of crack growth under variable amplitude loading
conditions. In this paper, the fatigue life under these conditions is evaluated. For this purpose, two-dimensional
simulations using finite elements are performed for different initial crack geometries. The models are subject to
mode I fracture and combinations of modes I and II. The crack propagation is performed incrementally through
the software FRANC2D. At each step, the stress intensity factor (SIF) is determined. All results of the SIF obtained
are then initialized in a Python language algorithm to calculate the fatigue life using the crack retardation and
acceleration model. Then, the fatigue life is evaluated for the different variable amplitude loading histories.