Experimental determination of stress intensity factors of cracks in sheet structures with bolted stiffeners

You are here: Homepage > Search

Experimental determination of stress intensity factors of cracks in sheet structures with bolted stiffeners

Güngör, S. / Nurse, A.D. / Patterson, E.A.

Sheet structures such as the wing and fuselage skins in aircraft usually consist of stringer-stiffened panels due to the requirements for sufficient stiffness. Evenly spaced stringers are attached to the skin material by means of riveting or adhesive bonding. The optical method of photoelasticity was used to measure stress intensity factors of cracks in stringer stiffened structures. From a photoelastic materials L-shaped stringers and plates with central holes were manufacrured, and one stringer was attached vertically to one side of each plate by means of bolting. In each test a crack was initiated from the side nearest the stiffener and extended in a direction perpendicular to the tensile load in the plate. With every crack extension the associated stress intensity factor was determined from the crack tip isochromatic fringe pattern by the multiple point over-deterministic method. The results showed that the presence of a stringer produces a significant reduction in the stress intensity factor and this reduction is affected by bolting position, thickness of the stringers and the method of load transfer from parent plate to the stringer.