A three-dimensional investigation of steady-state fatigue crack closure behavior for through-thickness and part-through flaws.

摘要

This Thesis describes how through-the-thickness variations in crack tip plasticity affect fatigue crack opening, and alter fatigue crack growth in transparent model materials. Complete three-dimensional crack opening profiles are measured by the use of optical interferometry for through-thickness, corner, and surface flaws. These crack surface separation data are then used to determine the crack opening load along the three-dimensional flaw perimeter.;The point-wise crack opening loads are compared with values obtained from various compliance measurement techniques. In addition, the results obtained from the polymer specimens are examined in context of the closure behavior reported for metal specimens by various investigators.