Effect of Stitching on In-Plane and Interlaminar Properties of Sisal/Epoxy Laminates

Abstract

The factors that influence in-plane mechanical responses and mode I interlaminar fracture toughness of stitched unidirectional sisal/epoxy laminates were studied in this paper. It was found that in-plane strength and stiffness of the laminates were not significantly affected by the stitching threads, while the interlaminar toughness was greatly improved, especially at higher sisal content. Unlike glass fiber reinforced polymer composites, sisal laminates have a rather high tolerance against the damages induced by stitching process. In addition, stitching expanded the fiber bridging zone and determined the R-curve profiles of sisal laminates. Factors including stitching density, diameter and species of stitching thread, continuity of stitching, and modification methods of sisal, were proved to greatly influence the delamination resistance of the laminates.

Structurally stitched NCF CFRP laminates. Part 1: Experimental characterization of in-plane and out-of-plane properties

“…To avoid flexural failure and torsion of the substrate beams of the double cantilever beam (DCB) specimens, a tabbed DCB (TDCB) configuration according to [17,22,52,53] was used to measure the mode I energy release rate of stitched and unstitched NCF laminates. A 25 lm thick fluorethylenpropylene (FEP) interlayer was inserted between the (B/2) NCFs (Fig.…”

“…It was found that increased yarn diameters (denoted as yd) and stitch densities are usually correlated with enhanced CAI and G 1R data of the composite laminate. With regard to the fiber types used for structural stitching, carbon and aramid yarns reduce crack propagation much more than glass, polyester, polyamide or sisal yarns [9,15,[18][19][20][21][22][23].…”

Improving interlaminar fracture toughness of flax fiber/epoxy composites with chopped flax yarn interleaving

“…But this may damage or at least change the microstructure of the fibers and usudoi: 10.1007/s11431-015-5911 -3 ally may introduce extra harmful chemical reagents such as coupling agents and alkali liquor in the process of operation. For laminated composites, some structural designing approaches can effectively improve interlaminar properties without the introduction of extra harmful reagents, such as z-pinning [10], stitching [11], 3D-weaving [12], etc. However, most of these techniques are costly or complicated in fabrication process and are normally with the penalty of the decrease in in-plane mechanical properties.…”

Biodegradable Polymer/Clay Nanocomposites

“…On the other hand, many researchers have reported obtaining well-intercalated structures when processing PBS with organo-modified clays such as C10A, C30B, MMT-LEA by either solvent casting, melt intercalation, or in situ polymerization Someya et al 2004;Shih et al 2007Shih et al , 2008Hwang et al 2009). Some authors have also reported the preparation of completely exfoliated PBS/clay nanocomposites by solvent casting (Shih et al 2007(Shih et al , 2008, melt intercalation , and in situ polymerization (Rong et al 2002) as well.…”