Measurement of the growth of sub-microscopic fatigue cracks by ellipsometry

Aluminum (1100) samples have been monitored with ellipsometry during fatigue cycling. Large changes in the ellipsometric parameters Δ and ψ are believed to be primarily associated with the formation of a sub-microscopic network of cracks. The ellipsometric results are interpreted in terms of the Fenstermaker-McCrackin model for surface roughening modified to simulate the crack system.