Mechanical performance of hybrid joints of aluminum sheets and laminated beech veneer plates: an experimental prestudy

Wood-based materials offer a high potential for the lightweight design of modern car bodies. Therefore, this prestudy investigates the static strength of screw-bonded lap joints of 1 mm-thick sheets of EN AW-6016-T4 aluminum alloy and 4.5 mm-thick plates consisting of three 1.5 mm-thick cross-laminated beech veneers. Plates with cover veneers oriented longitudinal (L) or transverse (T) to the uniaxial loading direction and with veneer stacking orders designated as L/T/L and T/L/T were used. Two self-cutting screws and polyurethane-based adhesive were used for hybrid joining. The stacking order and thus the fiber orientation of the cover veneers influenced the fracture behavior, which became evident in the force-displacement curve monitored during uniaxial shear-tensile testing of the joints. Veneer plates with the L/T/L stacking order withstood higher maximum tensile force but pro-vided lower pull-out resistance of the screws than plates with the T/L/T stacking order. However, regardless of the stacking order of the veneers the adhesive layer between the aluminum alloy sheet and the veneer plate mainly determined the maximum tensile force and thus the static strength of the joints, whereas the screws contributed only little