Mechanical, tribological, and physical performance of sisal fiber reinforced epoxy composites filled with Aningeria, Cordia Africana, and Cedar Sawdust

Abstract Composites are increasingly employed in aerospace, automotive, construction, sports, and defense industries owing to their high strength-to-weight ratio, corrosion resistance, and customizable properties. This study focuses on sisal fiber reinforced epoxy composites with sawdust fillers from three Ethiopian hardwood species: Aningeria (Kerero), Cordia Africana (Wanza), and Cedar (Tid). Using Taguchi design of experiments (L9 orthogonal array), nine composite samples were fabricated by the hand lay-up method with fiber orientations of 0/90°, 0/45°, and random. Mechanical (flexural, compression, impact), tribological (wear), physical (water absorption), and morphological (SEM) properties were systematically evaluated. Results revealed that Aningeria sawdust composites with 0/90° fiber orientation and 10 wt% filler exhibited the highest flexural strength (90.08 MPa), superior impact strength (78.4 kJ/m2), and lowest water absorption (0.53% after 72 h). Cordia Africana sawdust composites with 0/90° orientation and 20 wt% filler demonstrated the highest compressive strength (87.97 MPa) and optimal wear resistance (18 μm). Statistical analysis identified fiber orientation as the most significant factor (p < 0.05), contributing 73.27% to flexural strength and 90.12% to wear resistance. The study demonstrates that sisal fiber composites reinforced with locally available sawdust fillers provide an eco-friendly alternative to conventional synthetic composites, with promising applications in structural and defense components where balanced mechanical performance and sustainability are required.