Abstract
The importance of high residual stresses on fatigue crack propagation (FCP) is well known. The application
of laser shock peening (LSP) makes use of the residual stress effect on FCP by introducing
compressive residual stresses with a high penetration depth in metallic structures. While beneficial compressive
residual stress may result in a retardation, tensile residual stresses may lead to an acceleration
of the fatigue crack propagation and have to be treated with care. As residual stress fields always contain
region with tensile and compressive residual stresses, the question of an optimized residual stress field
aiming on the retardation of fatigue cracks arises. This work investigates the influence of LSP on FCP of
aluminium alloys using C(T)100 specimens. An efficient multi-step simulation to predict FCP in LSPinduced
residual stress fields is demonstrated, where the afford of the high dynamic LSP process
simulation is strongly reduced. The multi-step simulation is validated with a novel ‘experimental
simulation’ by applying predicted stress intensity factors to an untreated specimen experimentally.
Mechanism of the crack acceleration and retardation are investigated and linked to crack closure effects.
Numerically predicted areas of crack closure will be shown and can be found at the crack surfaces of the
experiments.
