Volume 5, Issue 4 (July 1977)
Laser Scanner for Exoelectron Display and Measurement of Fatigue Damage
Fatigue damage in metals can be displayed and assessed by means of exoelectron emission. The surface of a fatigue sample is scanned by a focused ultraviolet laser and the spatial distribution of the exoelectron emission is displayed on an oscilloscope. The operation of the system is illustrated by torsional and reverse bending fatigue tests on two different types of steel. The local intensity of the emission is a quantitative measure of the local deformation and permits the accumulated damage to be expressed in terms of the fraction of fatigue life expended.