Delayed failure in a shock-loaded silicon carbide A series of low stress shock impact experiments were performed on water to examine the dynamic response under tension and establish a lower bound for water rupture or cavitation threshold. The experimental cell configuration permitted particle velocity measurements at the water-air free surface separated by a 5-m-thick aluminized Mylar diaphragm. Water samples were triply distilled, de-ionized, and degassed prior to experiments. The average tensile strength for shock-induced cavitation in the water was found to be 8.7± 0.2 MPa. Experiments are compared with hydrocode simulations using a simple fracture criterion and published experimental data.

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The shock properties of epoxy-based particulate composites have been extensively studied in the literature. Generally, these materials only have a single particulate phase; typically alumina. This paper presents equation of state experiments conducted on five epoxy-based particulate composites. The shock stress and shock velocity states were measured for five different composites: two epoxy-aluminum two-phase composites, with various amounts of aluminum, and three epoxy-aluminum-(metal) composites, where the metal constituent was either copper, nickel, or tungsten. The impact velocities ranged from 300 to 960 m/s. Numerical simulations of the experiments of epoxy-Al are compared with mesoscale simulations of epoxy-Al2O3 composites to investigate the effect of the soft versus hard particulate; additionally, an epoxy-Al–W simulation was conducted to investigate the material properties of the second phase on shock response of these materials. In these epoxy-based particulate composites, the slope of the shock velocity-particle velocity curve appears to depend on the epoxy binder. It is shown that the addition of only 10 vol % of a second, denser metallic phase significantly affects the shock response in these composites.

ii This page intentionally left blank iii REPORT DOCUMENTATION PAGE Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing this collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden to Department of Defense, Washington Headquarters Services, Directorate for Information Operations and Reports (0704-0188), 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to any penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. REPORT DATE (DD-MM-YYYY) AFRL-RW-EG-TP-2012-003 SPONSORING / MONITORING AGENCY NAME(S) AND ADDRESS(ES)Air Force Research Laboratory, Munitions DirectorateOrdnance Division Energetic Materials Branch (AFRL/RWME) Eglin AFB FL 32542-5910 Technical Advisor: Dr. Jennifer L. Jordan SPONSOR/MONITOR'S ACRONYM(S)AFRL-RW-EG SPONSOR/MONITOR'S REPORT NUMBER(S)AFRL ABSTRACTThe shock properties of epoxy-based particulate composites have been extensively studied in the literature. Generally, these materials only have a single particulate phase; typically alumina. This paper presents equation of state experiments conducted on five epoxy-based particulate composites. The shock stress and shock velocity states were measured for five different composites: two epoxy-aluminum two-phase composites, with various amounts of aluminum, and three epoxy-aluminummetal composites, where the metal constituent was either copper, nickel, or tungsten. The impact velocities ranged from 300 to 960 m/s. Numerical simulations of the experiments of epoxy-Al are compared with mesoscale simulations of epoxy-Al2O3 composites to investigate the effect of the soft versus hard particulate; additionally, an epoxy-Al-W simulation was conducted to investigate the material properties of the second phase on shock response of these materials. In these epoxybased particulate composites, the slope of the shock velocity-particle velocity curve appears to depend on the epoxy binder. It is shown that the addition of only 10 vol % of a second, denser metallic phase significantly affects the shock response in these composites. The shock properties of epoxy-based particulate composites have been extensively studied in the literature. Generally, these materials only have a single particulate phase; typically alumina. This paper presents equation of state experiments conducted on five epoxy-based particulate composites. The shock stress and shock velocity states were measured for five different composites: two epoxy-aluminum two-phase composites, with various amounts of aluminum, and three epoxy-aluminum-...