Non-conventional failures caused by the edge effect in cross-ply laminates made of ultra-thin plies

In a fatigue testing programme of carbon/epoxy cross-ply laminates made ultra-thin plies, non-conventional failures are observed. These consist in longitudinal cracks the 90° layer parallel to loading direction instead conventional transverse perpendicular load direction. A potential reason for this failure is presence normal stress thickness Classical Lamination Theory predicts zero values component under loading, but free-edge alters state. The so-called “edge-effect” has been widely studied past, plies introduces new lower limits layer. Additionally, singularity, bimaterial corner generated by 0° and also investigated check its influence on state due low slight geometrical modification conceived remove isolating effect from pure edge effect. Numerical simulations alteration free samples, mechanical thermal carried out, distributions numerically computed, depending thickness. Detailed inspection 3D tomography done assess through-the-width propagation edge. predictions experimental X-ray inspections seem corroborate that responsible these failures.