Improvement of Mode I Interlaminar Fracture Toughness of Stitched Glass/Epoxy Composites

Abstract

This study examines the improvement of Interlaminar Fracture Toughness (IFT) of multilayered 3D glass/epoxy textile composites when through thickness reinforcement is introduced. Three stitching techniques have been examined: Modified Lockstitch (ISO-301), Single-yarn Orthogonal-stitch (ISO-205) and Double-yarn Orthogonal-stitch (ISO-205). It was found that the use of class ISO-205 manual-type stitched reinforcement significantly enhanced the Mode I-IFT, G IC measured using a Double Cantilever Beam technique. Furthermore, in every case, the use of class ISO-205 stitching and high stitch densities offer a significant improvement of 74.5 % on Mode I-IFT against interlaminar delamination.

A review on mode-I interlaminar fracture toughness of fibre reinforced composites

“…The fracture mechanics showed energy dissipation through matrix deformation, fibre de-bonding, fibre breakage and fibre pull-out Furthermore, a high stress concentration around stitch fibres can also reduce the fracture toughness. This is because a higher amount stitched fibres can cause an in-plane fibre misalignment [17,19]. Figure 4.…”

Mode I fracture toughness of fiber-reinforced polymer composites: A review

“…To determine the mode I fracture toughness according to the ASTM D5528 standard, three methods are used [78]: the modified beam method (MBT) [163–165], the compliance calibration (CC) method and the modified compliance calibration (MCC) method. The difference between them by means of fracture results is not more than 3.1%.…”

“…Some experimental studies have been conducted on stitched unidirectional or woven FRPC composites to find interlaminar delamination. It was found that the stitched FRPC laminates present significantly larger interlaminar toughness as compared to un-stitched laminates [4,74–79], and that an increase in stitch density caused an increase in mode I strain energy release rate [4,74–76]. A recent study [80] has been carried out on flax fiber-epoxy composite laminates to find the effect of stitching in-through-thickness direction on mode I fracture toughness.…”

Multiscale Polymer Composites: A Review of the Interlaminar Fracture Toughness Improvement

“…There are several manufacturing techniques available for making reinforcement preforms for composite laminates and these include (1) Braiding [80,81], (2) Stitching [82][83][84][85][86][87][88], (3) 3D Z-Pinning [89][90][91], and (4) 3D weaving [92]. The schematic of different types of 3D sandwich structure is depicted in Figure 5.…”

“…Braiding, which requires a complicated manufacturing process, may involve the loss of flexibility in laminate construction. ILFT can be substantially increased by adding the reinforcement in the thickness direction like non crimp fabrics with stitches, z-pinning, and metallic wire usage as well as 3-D structural composites [2,4,32,83,84,[93][94][95][96][97]. It was reported [4] that extensive crack branching caused toughening in the textile composites as the interlaminar crack followed a meandrous crack path inside a complex fiber architecture.…”