Mechanical Behavior of Thermoplastic FML-reinforced Sandwich Panels Using an Aluminum Foam Core: Experiments and Modeling

Sandwich panels manufactured using thermoplastic fiber-metal laminates (FML) skins and an aluminum foam core were tested under quasi-static and low-velocity impact loading conditions. The quasi-static properties of the sandwich beams were evaluated using the three-point bend test geometry. Energy absorbing mechanisms such as buckling and interfacial delamination in the FML skin, as well as indentation, crushing, and densification in the aluminum foam have been observed to contribute to the excellent energy absorbing characteristics offered by these systems. The low-velocity impact behavior of the sandwich panels was evaluated using an instrumented dropping weight impact tower and modeled using an energy balance approach. A breakdown of the energy absorption revealed that these sandwich structures absorb much of the impact energy due to contact and bending effects. Finally, four-point bend testing after low-velocity impact revealed that these systems offer excellent residual flexural strength with relative values remaining close to 80% of the original strength after a 32 J impact.