A BIAXIAL TEST SPECIMEN FOR CRACK-ARREST STUDIES

A biaxially loaded, single edge notched (SEN) fracture specimen, with mixed modes I and II loading, was used to study the crack arrest capab ility of a bonded and riveted tear strap without and with simulated mu ltiple site damage (MSD), MSD was modeled by a 50-percent groove witho ut which the running crack would inevitably kink due to K-parallel to loading. A total of thirty-one 2024-T3 aluminum specimens with various crack and MSD configurations were tested. The fracture parameters ass ociated with straight and curved crack paths were determined by using the experimental results to drive a dynamic finite element model of th e specimen in its generation mode, The crack kinking and extension cri teria were verified by the excellent agreement between the prediction based on these fracture parameters and the measured crack kinking angl es, Comparison between the test results generated by the biaxial stres s specimens and by those generated by small- and full-scale pressurize d fuselage rupture experiments showed that this specimen can be used t o prescreen the effectiveness of tear straps and crack arrestors in an airplane fuselage.