Impact Resistance of Potential Replacement Materials for Large Power Transformer Tanks

The protective effect of polymer coatings on Polymer Matrix Composite (PMC) panels against high-velocity ballistic impacts specifically as a potential replacement material for Large Power Transformer Tanks (LPT) has not been widely investigated. In particular, numerical predictions of the ballistic performance of the panels with coatings under impact are not available which is not surprising considering the complexity of the problem due to the prohibitive cost of the experimental testing. This numerical study was performed to understand the potential beneficial effects of a polyurea (PU) coating on PMCs, in application in LPT tanks. Glass fiber/epoxy and carbon fiber/epoxy composite panels individually and in a hybrid combination were subjected to 400 m/s ballistic impact. Using finite elements, the impact damage evolution for uncoated panels was investigated to determine the arrest depth as a function of panel thickness. Subsequently, the panels were evaluated for their ballistic response in the presence of PU coatings. It has been shown numerically for the first time that the addition of PU was three times more efficient in protecting the glass and carbon fiber panels against penetration than by increasing their thickness. In all three cases, adding a coating of PU decreased the estimated cost, mass, and thickness of the panels required to prevent penetration of the modeled projectile.