Investigation of the Intralaminar Fracture Toughness of Jute and Jute-Glass Hybridized Reinforced Plastic Composite
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Date
2026-10
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Addis Ababa University
Abstract
Fiber-reinforced polymer (FRP) composites are used extensively in the structural industry because of their excellent specific strength and stiffness properties. But, with the concerns about environment related to synthetic fibers, there is now an interest in natural fiber-reinforced polymer composites (NFRPCs). Although jute fibers have a low density, renewability, and cost, their low strength and hydrophilic nature restrict their use in building structures alone. A combination of natural and synthetic reinforcement, e.g. E-glass, gives a good compromise between mechanical properties and ecological advantages. The tensile, flexural and impact properties of jute-glass hybrids are reported, however, a lack of quantification of their intralaminar fracture toughness, crack propagation resistance (R-curve behavior) and the underlying micro-scale failure mechanisms
The study aims to explore the Mode I intralaminar fracture properties of woven jute and E-glass fiber unsaturated polyester composites treated with alkali (5 wt% NaOH). Laminates were produced by controlled hand layup process with three different variations in laminate construction, all having identical total fiber volume fraction (Vf) of 30%, namely a pure jute control laminate “J”, a sandwich-like hybrid laminate “H_1”, and an interleaved hybrid laminate “H_2”. Doubly-tapered compact tension (2TCT) specimens were tested for Mode I fracture in a universal testing machine. Considering the critical energy release rate (G_IC) and crack-growth resistance (R-curves) parameters, a two-stage compliance calibration procedure was performed in Abaqus/CAE 2020 software package along with Python scripting and a polynomial data-reduction was obtained to carry out the analysis. In addition, macro-fractography, optical microscopy and X-ray radiographical analysis were employed to establish the progression of damage inside the specimen.
Experimental and numerical results show that hybridization has a significant effect on the crack-growth resistance. The critical energy release rate (G_IC) for the pure jute composite increased from 2.887 kJ/m2 to 20.74 kJ/m2 (86.08% higher) for H_1 and 25.03 kJ/m2 (88.46% higher) for H_2. The propagation values (G_IC-PROG) reached 4.133 kJ/m2, 25.809 kJ/m2, and 33.645 kJ/m2 for J, H_1, and H_2, respectively. It was found that results of the FE-based reduction method are more accurate for estimating orthotropic fracture toughness than isotropic approximations, a finding that was confirmed by comparison with conventional ASTM D5045 formulations, which underestimated orthotropic fracture toughness by 37%-41%. Progressive damage stabilization was observed from the initial appearance of the cracks up to a crack length of 40 mm, followed by the emergence of the multi-interface fiber bridging, tow splitting and delamination phenomena. Interleave of glass plies (H_2) gave the best toughest value due to the multiple interlaminar shear stresses. These results provide quantitative design recommendations for designing lightweight, environmentally friendly and damage-tolerant hybrid structural composites.
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Keywords
jute fiber, hybrid composites, intralaminar fracture toughness, R-curve, doubly-tapered compact tension, finite element data reduction, fractography