Correlations between crack initiation and crack propagation lives of
notched specimens under constant and variable amplitude loading
This paper starts with an overview of the application of the three
guidelines (GL) of the German Research Association of Mechanical
Engineers (FKM). Each of these provides algorithms for calculating
fatigue lives of components under constant or variable amplitude
loading, however, with underlying different failure criteria, i.e.
technical crack initiation life (GL-nonlinear), fatigue crack growth
life (GL-fracture mechanics), and total fracture life (GL-linear). This
paper introduces the U-Concept which has been evaluated from a large
structural durability database. The U-Concept is a small add-on to the
Local Strain Approach (LSA) which is the backbone of the GL-nonlinear.
It enables 1) to directly calculate the fatigue life to total fracture
based on elastic-plastic material behaviour according to the LSA, or 2)
to estimate the remaining fatigue life from crack initiation to fracture
without a crack growth simulation.