Tensile fatigue response of a novel carbon/flax/epoxy hybrid composite under strain-controlled and stress-controlled amplitude

Abstract

This is the first study on the fatigue tensile performance of a novel hybrid composite made as Type A (i.e. woven carbon fibers plus unidirectional flax fibers [WC2/0F12/WC2]) or Type B (i.e. woven carbon fibers plus oblique flax fibers [WC2/(±45)F6S/WC2]) in epoxy resin. Composite plates were examined under constant strain amplitude using conventional fatigue tests and constant stress amplitude using thermographic stress analysis at 5 Hz cycling with a constant amplitude ratio of 0.1. For conventional fatigue, the max strain εmax versus cycles to failure Nf curve for Type A was log (Nf) = 9.7–588.2εmax, while for Type B it was log (Nf) = 14.9–1000εmax; neither material had a true endurance limit since curves never became horizontal. For thermographic stress analysis, high-cycle fatigue strength for Type A was 231.7 MPa (i.e. 56% of ultimate tensile stress σut), while for Type B it was 203.2 MPa (i.e. 60% of σut).

Influence of abrasive water jet and conventional drilling on the fatigue performance of hybrid carbon/flax laminates

“…The intra-ply hybrid was observed to exhibit a superior fatigue life (over 1000%) than the flax composite, and the inter-ply hybrid exhibited a lower fatigue life. This observation is contradicted by Al-Hajaj et al 21 who reported a 40% increase in HCFS for a woven carbon/0°flax configuration and an 81% increase for a woven carbon/±45 • flax configuration. Ameur et al 23 observed that hybridization of the flax with carbon resulted in a higher number of cycles to failure than the pure carbon composite.…”

“…Nevertheless, results from existing literature on non-open hole carbon/flax specimens and flax specimens with holes machined by AWJ and CD 19,21 are examined to glean indirect effects on fatigue behavior. The HCFSs calculated by Al-Hajaj et al 21 were based on thermographic measurements of non-hole hybrid woven carbon/unidirectional flax composites (56% UTS) as well as hybrid woven carbon/angle ply flax composites (60% UTS). For both machining methods of the CF[0] layup and CF[ ± 45]-CD, there is less than a 2% difference in the HCFS between the open hole and non-hole.…”

“…To improve the fatigue properties of flax composites, recent studies have proposed the hybridization of flax fibers with carbon fibers because of their high strength and modulus-to-weigh ratios and excellent fatigue resistance. [20][21][22][23] Islam et al 20 studied the fatigue behavior of interply and intra-ply hybrid flax/carbon fiber composites. The intra-ply hybrid was observed to exhibit a superior fatigue life (over 1000%) than the flax composite, and the inter-ply hybrid exhibited a lower fatigue life.…”

“…There are no published results to compare the results of this study against because it is the first study, to the best of our knowledge, to examine the fatigue behavior of open-holed hybrid carbon/flax composites. Nevertheless, results from existing literature on non-open hole carbon/ flax specimens and flax specimens with holes machined by AWJ and CD19,21 are examined to glean indirect effects on fatigue behavior. The HCFSs calculated by Al-Hajaj et al21 were based on thermographic measurements of non-hole hybrid woven carbon/unidirectional flax composites (56% UTS) as well as hybrid woven carbon/angle ply flax composites (60% UTS).…”

Efficient accelerated assessment of fatigue life in Kevlar, Flax, and Kevlar/Flax hybrid composites

“…Each sample was subjected to sequential cyclic loading until stabilization was attained for each stress level, progressively increasing until failure. Previous studies 19,20 paired Flax with stiffer fibers such as carbon and glass, which are more inclined to outperform the Flax fibers in terms of mechanical performance. Both carbon and glass have been shown to be effective, albeit as hybrids with Flax, and they are the prime drivers of performance because of their dominant stiffness.…”