Mechanical and microstructural properties of notched E-glass/vinyl ester composite materials subjected to the environment and a sustained load

Flaws may be created in composite materials during manufacturing, machining, or use. Composites with such flaws, when subjected to adverse environmental conditions in the presence of a sustained load, may have reduced mechanical properties and changes in their microstructural properties up to failure. E-glass/vinyl ester composite coupons with a single edge flaw have been conditioned for periods up to 7900 h at room temperature and at an elevated temperature, with and without a sustained load, to determine the changes in the tensile properties and damage mechanisms which occur with the introduction of the flaw. The early damage mechanisms have been found to change from transverse matrix cracking, fiber cracking, and occasional edge delaminations for unnotched specimens to the growth of a significant matrix crack from the notch tip and well-defined longitudinal tow debonding for notched specimens.