The aim of this work is to understand the erosion mechanism caused by repeated
water droplets impingement on a metallic structure, and then perform numerical simulations of the
damage. When a high velocity water droplet with small diameter impacts a rigid surface,
interaction is driven by inertial effects. Upon impact, the “water-hammer” pressure appears by
inertial effect at the center of the contact though the maximum pressure occurs on the envelope of
the contact area. Lateral jetting occurs by compression when the wave front travelling inside
droplet overtakes the contact area. Concerning the structure, erosion is due to fatigue crack-
ing. First, material grains are weakened during an “incubation” phase. After a large number of
impacts, micro-cracks emerge and lead to ejection or fracture of grains, what is called “am-
plification” phase. Numerical simulation including rigid solid allows to locate the most loaded
zones of the area, by observing the pressure and mainly the impulse. A 2-way coupling compu- tation
with fluid-structure interaction at macroscopic scale allows to confirm the fatigue-based mechanism
by observing the hydrostatic stress. Finally, erosion program developed with Dang Van criterion
provides the location of the most eroded zones of the structure during a loading cycle. They
locate at the edge of jetting zone, which shows the influence of microjets in the
erosion mechanism
