Influence of fibre spacing and pitch angle on the stab resistance of SLA 3D-printed porous Bouligand-structured polymers

This paper considers the stab resistance of porous Bouligand structured additively manufactured polymers. We independently varied the fibre spacing distances (0.5 mm to 1.25 mm) in the structures (affecting porosity), as well as the inter-ply pitch angles (10°–90°). Samples were tested using a drop stab test apparatus, and forces determined using both high speed videography and accelerometry. Three damage metrics were assessed including, penetration depth, damaged area (footprint) based on UV microscopy, and damaged volume (crater) based on CT scans. Maximum stab force was measured at 525 N (30° pitch, 0.5 mm spacing), while the largest damage volume reached 175 mm 3 (10° pitch, 1.25 mm spacing). We find that both fibre spacing distances and pitch angles affect stab force resistances and stab damage tolerance, with spacing distances having the predominating influence, and pitch angles having a minor influence. Linear correlations (R 2 > 0.99) were observed between apparent density and both stab force and damage metrics enabled the creation of a predictive model. Moreover, the stab force increases linearly with increasing apparent density for all pitch angles, whereas each of the damage metrics is found to decrease linearly as a function of increasing apparent density with r > 0.99, 0.93 and 0.96 when comparing specifically penetration depth, damaged area and damaged volume, respectively. • The optimal pitch angle of those researched for stab damage tolerance is 30°. • Lower fibre spacing experience higher stab forces, but are more brittle in failure. • Higher fibre spacing increases material ductility, but experience more internal damage. • At all pitch angles, both stab force and stab damage tolerance can be predicted.