Comparative bending performance and structural performance of cassava peel ash and coconut husk ash hybrid reinforced Al2O3/AA6063 composites under extreme loading conditions

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)/Al 2 O 3 - and coconut husk ash (CHA)/Al 2 O 3 -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 Al 2 O 3 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.