Influence of UHMWPE fiber and Ti6Al4V metal surface treatments on the low-velocity impact behavior of thermoplastic fiber metal laminates

The unique combination of alternate thin layers of metal and complete thermoplastic fiber-reinforced polymer (FRP) gives birth to a new generation of hybrid thermoplastic fiber metal laminates (T-FML), which are considered for high impact resistance applications. T-FML is fabricated by Ti6Al4V metal alloy and ultra-high molecular weight polyethylene (UHMWPE) with infusible liquid methyl methacrylate thermoplastic resin (Elium®). The impact damage resistance of T-FML depends on the interlaminar interface and metal thermoplastic composite interface (MTCI). Higher interfacial properties provide improved stiffness and resistance to the delamination of crack growth in T-FML during an impact loading. Fiber and metal surfaces are modified to enhance the interlaminar interface and MTCI. The fiber surface is treated by a simple deposition of polydopamine (PDA) with the addition of 0.03 wt.% multiwalled carbon nanotubes (MWCNT), and the metal surface is treated by using an electrochemical process. Experimental investigations were carried out on the T-FML composite laminates to determine the low-velocity impact behavior at three different impact energies (43 J, 50 J, 80 J). The results revealed that the non-impacted Ti alloy face sheet on the rear side of the T-FML plays an important role in absorbing the impact energy by creating a single crack in the rolling direction. Also, the single crack growth is suppressed when the MTCI is improved after the fiber and metal surface treatment. Graphical abstract Metal and fiber surface treatment enhances the delamination resistance at the metal and thermoplastic composite interface offering lower structural damage.