Hypervelocity Impacts of Shear Thickening Fluid Imbibed Metallic Foam Core Sandwich Panels

Hypervelocity impact (HVI) experiments were carried out on two configurations of open cell foam core sandwich composite panels both infused with a shear thickening fluid (STF). The first configuration consisted of an aluminum facesheet, 1.27 cm thick 6.35 pores per cm open cell aluminum foam core, and a rear aluminum facesheet. The second configuration consisted of an aluminum facesheet, 1.27 cm thick aluminum honeycomb core, an intermediate aluminum sheet, 0.64 cm thick 6.35 pores per cm open cell aluminum foam core, and a rear aluminum facesheet. The open cell foam core of each configuration was infused with a STF consisting of 0.225 mass fraction of Aerosil 200 fumed silica in 200 molecular weight polyethylene glycol (PEG). HVI experiments were conducted for two specimens of each configuration employing a 1 mm diameter aluminum projectile and impact velocities of approximately 3-5 km/s. For comparison, the HVI experiments were repeated using additional specimens where the open cell foam cores were infused with the STF’s liquid phase only, PEG. All specimens regardless of configuration or imbibed fluid prevented penetration of the rear facesheet. However, the STF infused core of the second configuration was not perforated. For the first configuration, in addition to the projectile entrance holes, the front facesheet sustained out of plane deformation local to the point of impact, and the amount of deformation was similar for the PEG and STF infused specimens. Additionally, the PEG infused specimens sustained a small amount of out of plane deformation of the rear facesheet, while the STF infused specimens did not. Non-destructive computed tomography (CT) scans of the impacted specimens were conducted to investigate the internal damage. Comparisons of the CT scans indicated that the PEG infused specimens sustained a slightly greater volume of core damage than the STF infused specimens.