Abstract
Abstract
The growing demand for lightweight, sustainable structural materials continues to drive interest in agro-
waste-reinforced AMCs. However, existing studies have largely focused on hardness, tensile strength, and
wear behavior, with limited attention to the broader flexural response that governs structural performance
under severe bending and extreme loading. The objective of this study is to systematically investigate and
compare the flexural behavior, energy dissipation, and progressive damage mechanisms of hybrid cassava
peel ash (CPA)/Al2O3- and coconut husk ash (CHA)/Al2O3-reinforced AA6063 composites. This study
presents a novel, comprehensive flexural assessment that extends beyond conventional strength analysis to
simultaneously evaluate flexural strength, modulus, stiffness, strain at failure, deflection, specific energy
absorption, work of fracture, and structural performance under severe bending loads for these specific hybrid architectures. The hybrid composites containing a total reinforcement of 10 wt.% at varying agro-
waste-to-alumina ratios were fabricated via stir casting and evaluated using ASTM D790 three-point
bending tests. Key findings reveal that the flexural response is fundamentally governed by the
reinforcement architecture. CPA-reinforced composites exhibited superior peak load-bearing capability and
structural rigidity, achieving a maximum flexural strength of 329.44 MPa, a flexural modulus of 12.40 GPa,
and stiffness of 296.51 N/mm at intermediate reinforcement levels. Conversely, CHA-reinforced
composites demonstrated greater deformation accommodation, achieving a strain at failure of 0.21 and a deflection of 11.44 mm. Maximum energy absorption values of 9.87 J (CPA-5) and 8.85 J (CHA-2) were
obtained. While balanced hybrid reinforcement provided the most favorable combination of strength,
stiffness, fracture resistance, and energy dissipation, excessive replacement of Al2O3 with agro-waste
particulates reduced overall structural efficiency. The findings demonstrate that agro-waste/ceramic
hybridization can be synergistically tailored to stiffness, strength, damage tolerance, and lightweight
structural efficiency for sustainable AMCs in severe bending and extreme loading environments.