This paper describes a research program conducted to enable accurate prediction of the impact tolerance of the shuttle Orbiter leading-edge wing panels using physics-based codes such as LS-DYNA, a nonlinear explicit transient dynamic finite element code. The shuttle leading-edge panels are constructed of reinforced carbon-carbon composite material, which is used because of its thermal properties to protect the shuttle during reentry into the Earth's atmosphere. Accurate predictions of impact damage from insulating foam and other debris strikes that occur during launch require materials characterization of expected debris, including strain-rate effects. First, analytical models of individual foam and reinforced carbon-carbon materials were validated. Next, analytical models of foam cylinders impacting 6 × 6 in. reinforced carbon-carbon flat plates were developed and validated. LS-DYNA pretest models of the reinforced carbon-carbon flat-plate specimens established the impact velocity of the test for three damage levels: no detectable damage, nondestructive-evaluation-detectable damage, or visible damage such as a through-the-thickness crack or hole. Finally, the threshold of impact damage for reinforced carbon-carbon on representative Orbiter wing panels was predicted for both a small through-the-thickness crack and for nondestructive-evaluation-detectable damage.
展开▼
