An experimental study of the closure behavior of short and long cracks

Experiments were conducted on 2024-T3 aluminum specimens. The laser-based interferometric strain/displacement optical system was used to measure crack opening displacement. The displacement data were measured near the crack tip, at the crack mouth, and at other locations along the crack line for both short and long cracks. The dependence of opening load ratio on measurement locations was observed. The ratio decreased systematically as the measurement locations moved away from the crack tip. However, the ratio stayed roughly the same for the near tip surface measurements at various crack lengths.