The effect of aluminum and titanium sequence on ballistic limit of bi-metal 2/1 FMLs

In the present study, the ballistic limit, absorbed energy and the failure mechanism of fiber metal laminates (FML) with three different arrangements of layers were investigated. Each FML specimens consisted of two metallic layers including aluminum 2024-0(Al) or titanium 6Al-4V(Ti) reinforced by E-glass unidirectional fiber and araldite/aradur5052 Huntsman epoxy resin(R). Three arrangements of FML's including Al/R/Ti, Al/R/Al and Ti/R/Al arrangements were considered in this study. The study was performed by experiment and simulation. It was shown that the ballistic limit of Al/R/Ti specimen was higher than those of Ti/R/Al and Al/R/Al specimens. Replacing an aluminum layer in Al/R/Al by a titanium 6Al-4V layer led to considerable increase in ballistic limit and the absorbed energy in both titanium FMLs. 82% and 64% increase in the average absorbed energy/thickness was observed in Al/R/Ti and Al/R/Ti specimens, respectively. It was also shown that the failure mechanism of the titanium layer changed from petalling for Al/R/Ti to plugging for Ti/R/Al.