T* ε integral values associated with stable, curved crack growth in biaxially loaded, fatigued precracked, 2024-T3 single edge notched (SEN) specimens were determined. The SEN specimens were loaded under combined Modes I and II and mimicked the flapping of a failed lap splice joint of a pressurized airplane fuselage. Most specimens were provided with a tear strap, which was either bonded, bonded and riveted, or integrally machined (machined pad-up) in the specimen. The stably growing crack curved and either penetrated or curved again upon hitting the tear strap. The displacement field, which was determined by Moire interferometry as well as with finite element analysis, was used to directly determine the T* 1ε and T* 2ε integral values. These T* ε values agreed reasonably well with those determined by an elastic-plastic finite element modeling of the experiments. T* 1ε was identical to that obtained previously for pure Mode I crack extension while the T* 2ε integral oscillated about its null value. The results of this study suggest that T* 1ε could represent the resistance for locally self-similar crack growth and that a crack will curve in the direction of vanishing T* 2ε.
|Number of pages||16|
|Journal||ASTM Special Technical Publication|
|State||Published - 1999|
|Event||Proceedings of the 1998 Symposium on Mixed-Mode Crack Behavior - Atlanta, GA, USA|
Duration: May 6 1998 → May 7 1998