Effect of Coatings and Processing on Failure Mechanisms of Polycarbonate Material. Phase 1.

摘要

The subject effort identified the first order damage mechanisms and governing parameters contributing to the occurrence of a ductile to brittle transition in the mechanical behavior of ballistically impacted polycarbonate materials with protective coatings. Polycarbonate embrittlement is associated with a severe reduction in impact resistance as well as extensive in-plane cracking and rear surface debris. In plane cracking can severely block the visual surface and target debris can cause debilitating eye injury. The current effort included: (1) Definition of contact pressures associated with the impact of polycarbonate material with and without protective coatings; (2) Definition of polycarbonate substrate and coating configurations of interest; (3) Stress wave response analysis; (4) Structural and fracture mechanics analysis; and, (5) Fabrication, quasistatic penetration, and ballistic testing of polycarbonate materials with or without protective coatings. Hardening recommendations designed to mitigate the influence of damage mechanisms identified as contributing to the brittle failure of polycarbonate were also rendered.