Study of the influence of stacking sequence in the failure of crossply laminates manufactured with ultra-thin plies

Abstract

Numerous studies on the use of laminates manufactured with ultra-thin composite laminates have shown the existence of a significant delay in the appearance of damage, a phenomenon known as the Scale Effect. To study the effect that layer thickness may have on the damage mechanisms that appear at higher values of the load, this work analyses whether the use of ultra-thin laminates exhibits a better behaviour in the instants prior to failure and laminate rupture. For this purpose, different laminates have been manufactured with ultrathin thickness material formed by the same number of laminae oriented at 0 and 90 degrees, but with different stacking sequences, distributing the laminae such that the thicknesses of the resulting layers are different. The laminates have been subjected to uniaxial tension up to values close to the ultimate load in order to observe and compare the different damage morphologies that appear in the 90 and 0 degrees layers, using optical microscopy techniques for the observation of the damage. On the other hand, the loads for which the failure of the selected laminates happens have also been compared. The results obtained from this study show different behaviour of the laminates depending on the thickness of their 0 and 90 degrees layers in the moments prior to failure and at the instant when failure occurs.