Fiber-Metal Laminate Panels Reinforced with Metal Pins

Abstract

Fiber-metal laminates (FMLs) are key to modern composite structures and metal-composite coupling is crucial to improve their effectiveness. Cold-metal transfer (CMT) PIN welding, in correlated efforts, has been successfully explored as a metal-composite hybrid joining approach. This work proposes a novel development on FMLs, which consists of introducing metal pins welded by CMT PIN for anchoring their metal and composite layers together. Thus, miniaturized FML panels with different pin deposition spacing and patterns are evaluated with emphasis in drop-weight testing followed by buckling and by means of Iosipescu shear test as complement. They are also subjected to cosmetic and preliminary modal analyses. Besides not adding significant weight, the pins does not make the panels more brittle and their distribution does not imply significant effect in the capacity that the panels have to dissipate impact. The panels with pins exhibit a less catastrophic trend, indicating damage tolerance improvement as significantly higher loads at longer axial displacements in buckling test after impact are achieved. The anchoring effect of the pins is confirmed throughout the shear test results. The pins also significantly increase the damping factor of the panels and the changes in their metal surfaces by the CMT PIN process are considered as irrelevant.