A study of the effect of CPCs on fatigue crack propagation in a representative fuselage lap joint specimen

This paper investigates the effect of corrosion preventive compounds (CPCs) on the growth of cracks emanating from fastener holes in a typical (pressurised) fuselage lap joint. To this end we present the results of a series of fatigue tests in room temperature dry conditions as well as tests where the specimen has been treated with CPCs. The results of these tests reveal that although CPCs do not significantly affect the stresses in the joint they can have a detrimental effect on fatigue crack growth in a representative structural joint when tested in laboratory air.

► CPCs only have a small effect on the load transfer in fuselage lap joints.
► Nevertheless CPCs can have a detrimental effect on the crack growth rate associated with long cracks.
► There is often a bi-linear relationship between the log of the crack length and the number of cycles.
► However, specimens can also commence growth with a slope equal to the higher of these two slopes.