Compressive Response of Lightweight Ceramic Ablators: Silicone Impregnated Reusable Ceramic Ablator
| Autor: | Huy K. Tran, Kelly E. Parmenter, Christine E. Szalai, Daniel J. Rasky, Frederick Milstein, Karl Shuman |
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| Rok vydání: | 2002 |
| Předmět: | |
| Zdroj: | Journal of Spacecraft and Rockets. 39:290-298 |
| ISSN: | 1533-6794 0022-4650 |
| Popis: | Silicone impregnated reusable ceramic ablators are highly porous fibrous ceramic substrates that are partially impregnated with silicone. The ablators are used as heat shields for planetary entry. The compressive responses of virgin and charred ablators, and their corresponding fibrous substrates, are reported. The fibers in the materials tend to be randomly and uniformly aligned parallel to a preferred plane, resulting in anisotropic mechanical properties. Compressive loads, applied either parallel or normal to the preferred fiber-alignment plane, yielded initial stress-strain responses that were fairly linear, to strains of about 1 or 2%. For virgin ablators loaded normal to the fiber-alignment plane, the initial linear response was followed by a rapid decrease in the slope of the stress-strain curve, after which the stress increased asymptotically with strain, to strains over 80%, and stresses approaching 10 MPa, without macroscopic failure. In all other cases, after the initial linear response, the stress varied in an erratic, roughly horizontal, manner, without exceeding about 3 MPa. This erratic stress path indicates discontinuous breaking of the bonds between the fibers and/or buckling of the fibers. Good correlation between compressive strength and hardness was found among materials with this latter response. Comparisons are made with the behavior of phenolic impregnated carbon ablator. |
| Databáze: | OpenAIRE |
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