Effect of Date Palm Fiber Content on the Tensile Behavior of Epoxy/Date Palm Fiber Bio-Composites: Experimental Investigation and Finite Element Analysis

Abstract

Natural fiber-reinforced composites have attracted considerable attention as environmentally sustainable substitutes for conventional synthetic materials. Nevertheless, determining an appropriate fiber loading remains a critical issue, since higher reinforcement contents may improve stiffness while adversely affecting ductility and overall mechanical behavior. In the present work, the tensile performance of epoxy composites reinforced with untreated date palm fibers (DPFs) collected from southern Tunisia was investigated through a combination of experimental tensile tests and finite element analysis (FEA). Four fiber mass fractions (5, 10, 15, and 20 wt.%) were considered to evaluate the influence of reinforcement content on the mechanical response of the developed bio-composites. The experimental findings revealed a progressive increase in tensile strength, from 25.3 MPa at 5 wt.% fiber content to 31.6 MPa at 20 wt.%, while the Young’s modulus increased from 2.0 GPa to 3.67 GPa. Conversely, the strain at failure decreased from 4.8% to 2.5%, reflecting a gradual loss of deformability as the fiber fraction increased. The formulations containing 10 wt. % and 15 wt.% fibers provided a favorable compromise between stiffness, strength, and deformation capability. The numerical predictions obtained from the homogenized linear elastic FEA model showed good agreement with the experimental results, with coefficients of determination (R²) of 0.979 for tensile stress prediction and 0.994 for strain prediction. The proposed numerical approach provided a reasonable macroscopic approximation of the tensile response despite the simplified homogenization assumptions adopted. The novelty of this work lies in the combined experimental–numerical investigation of untreated Tunisian date palm fiber/epoxy bio-composites and the assessment of the applicability and limitations of a simplified homogenized FEA approach for predicting their tensile behavior.