Biaxial testing of cruciform specimens representing characteristics of a metallic airplane fuselage section

•Biaxial tests of cruciform specimen representing an aircraft fuselage section.•Experimental study of fatigue cracks in aluminum alloys with ΔK up to 130 MPa√m.•Calculation of stress intensity factors based on digital image correlation (DIC).•Determination of ΔKeff with DIC results. Based on biaxial tests with cruciform specimens, the scenario of fatigue cracks in the upper fuselage section between the wings and the tail unit of a commercial single aisle aircraft has been studied. Two different types of specimen were designed, namely for the scenario of a circumferential crack across a broken stringer and for a longitudinal crack parallel to the stringers. With crack length up to 2a ≈ 610 mm, maximum mode I stress intensity factors of 160 MPa√m were obtained for the commercial aluminum alloys AA2024-T351 and AA5028-H116. All experiments were supported by digital image correlation to obtain the actual deformation fields of the specimens. Based on these data stress intensity factors and J integrals were computed with a line integral procedure. Furthermore, plastic zone and crack closure effects were studied.