Notch effect on the linear elastic fracture mechanics values of a polysulfone thermoplastic polymer

Abstract

Users of the most popular procedures for determining the linear elastic fracture mechanics parameters on polymers have noted that the repeatability and reproducibility of the results depend strongly on the quality of the notches generated. In an attempt to provide a better understanding, polysulfone specimens were pre-cracked using classical razor blade methods (tapping and sliding), and also by the femtosecond pulsed laser ablation technique. These specimens were analyzed, and the critical stress intensity factor was determined. The ablated specimens showed very good notch quality, the sharpest crack tip radii, displayed neither mechanical nor thermal damage in front of the crack tip, and were very consistent, providing both a lesser scatter and a statistically significant lower critical stress intensity factor than the razor blade pre-cracked specimens. Finally, some consideration and advice for suitable generation of notches are also given.