Bending behavior of laminated aluminum-wood composites made of thin birch veneers – a prestudy

The demand for sustainable lightweight materials that replace conventional non-renewable materials has strongly increased in the automotive sector. In this respect, wood as a renewable resource provides favorable mechanical properties. However, its low fracture elongation under tensile loading, susceptibility to splintering, and high anisotropy require reinforcement strategies to achieve the desired structural performance. Therefore, this study optimizes aluminum-wood composites for improving their performance under quasi-static and dynamic bending. The composites were fabricated from birch plywood, consisting of nine adhesive-bonded birch veneers (0.5 mm thickness each, bonded with phenol formaldehyde), reinforced on one side with a 1 mm-thick EN AW-6016-T4 aluminum alloy sheet. To bond the aluminum sheet to the plywood, three different adhesives were applied: phenol formaldehyde (PF), two-component polyurethane (PUR), and two-component epoxy (EP). The layered structure of the composite reduced the variation of the bending properties of plywood. Compared to aluminum alloy sheets of similar weight, the aluminum-wood composites showed superior lightweight potential as well as improved bending performance in terms of maximum bending force and impact energy. Bending behavior was comparable for PF- and PUR-bonded composites, with negligible debonding under quasi-static loading. EP-bonded composites exhibited pronounced debonding.