Tapered laminates under static and fatigue tension loading

Static and tension–tension fatigue tests have been undertaken on carbon-fiber/epoxy specimens with tapered sections. The effects of the value of the slope angle, a delamination in the tapered section, and ageing have been investigated. The results of this study show that the stress amplitude of the civil-aircraft fatigue spectrum does not create any damage in the tapered section and has no contribution to the propagation of delamination when 132 g/m2 material is used, with maximum 20° tapered specimens. A static strength reduction is induced by ageing. No effect on duration is observed. A statistical analysis is made to fix, on a A-value or B-value basis, the relationship between fatigue stress, fatigue life and residual strength.