Micromechanical and Numerical Homogenization of Coconut Shell Powder–Reinforced Epoxy Composites

This study develops a micromechanical and numerical framework to predict the effective elastic properties of coconut shell powder (CSP)‐reinforced epoxy composites. Classical analytical homogenization models are used to systematically examine the effects of reinforcement volume fraction, particle geometry, orientation distribution, and porosity, while finite element simulations on periodic representative volume elements (RVEs) are used for the spherical‐particle reference configuration. Particle geometry and orientation are shown to govern the symmetry of the effective stiffness tensor. The predicted Young's modulus of the four‐phase configuration increases from 4.23 GPa for neat epoxy to approximately 5.15 GPa at 50 wt% CSP, corresponding to a volume fraction of 48.61%. Porosity is represented by a zero‐stiffness void phase. A progressive multi‐phase Mori–Tanaka framework is then constructed by successively incorporating an orientation distribution function (ODF)‐based orientation description, bimodal morphological heterogeneity through coexisting spherical and ellipsoidal inclusion families, and an explicit porosity phase. Among the three Mori–Tanaka variants investigated, the four‐phase model shows the closest overall agreement with the experimental reference data, with an estimated mean absolute relative error of 3.55%. Because the CSP constituent properties were derived from the composite data used for comparison, this agreement reflects internal consistency rather than independent validation.