<title>Multiple simulated waterdrop impact damage in zinc sulfide at supersonic velocities</title>

The effects of supersonic waterdrop impacts on infrared-transmitting materials are relatively unknown. This is due to the general lack of testing capabilities for these impact conditions, however current flight requirements are placing an increased emphasis on this velocity regime. The GRC Multiparticle Impact Facility was used to obtain multiple nylon bead simulations of waterdrop impacts on zinc sulfide specimens. Nylon bead impact damage on zinc sulfide is shown to be quite similar to that due to waterdrop collisions for several of the impact conditions. The validity of the nylon bead/waterdrop impact correlation is being more fully developed as the range of comparable impact conditions is increased. The nylon bead impact data base for zinc sulfide includes three impact angles (90 degree(s), 45 degree(s), and 30 degree(s)) and three bead diameters (1.6 mm, 2.0 mm, and 3.2 mm) for a range of impact velocities.