Compressive Response of Lightweight Ceramic Ablators: Phenolic Impregnated Carbon Ablator

Parmenter, Kelly E.; Shuman, Karl; Milstein, Frederick; Szalai, Christine; Tran, Huy K.; Rasky, Daniel J.

doi:10.2514/2.3675

Cited by 35 publications

(8 citation statements)

References 7 publications

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“…Their networks spanned densities of 1.5-1.8 g/cc and were generated by manually abstracting hydrogen atoms from a hydrocarbon precursor and quenching the resulting pure carbon network. The computed κ of these highly sp 2 networks fell between 1.25 and 1.5 Wm −1 K −1 , in very good agreement with our calculations.…”

supporting

confidence: 78%

Effect of microstructure on the thermal conductivity of disordered carbon

Suarez-Martinez

Marks

2011

Applied Physics Letters

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Computational methods are used to control the degree of structural order in a variety of carbon materials containing primarily sp 2 bonding. Room-temperature thermal conductivities are computed using non-equilibrium molecular dynamics. Our results reproduce experimental data for amorphous and glassy carbons and confirm previously proposed structural models for vitreous carbons. An atomistic model is developed for highly oriented thin films seen experimentally, with a maximum computed thermal conductivity of 35 Wm −1 K −1 . This value is much higher than that of the amorphous and glassy structures, demonstrating that the microstructure influences the thermal conductivity more strongly than the density.

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supporting

confidence: 78%

Effect of microstructure on the thermal conductivity of disordered carbon

Suarez-Martinez

Marks

2011

Applied Physics Letters

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“…The initial parts of all the curves increase linearly with a smaller slope and then up to the vertex with a larger slope which is taken as the compressive strength [33]. In the ensuing non-elastic stage, the sudden drop of stress in xy -direction indicates that plastic instability occurs attributed to the separation of carbon aerogels from carbon fibres [33,34]. In the z -direction, however, the fibres arrangement is perpendicular to the direction of the compression load.…”

Section: Resultsmentioning

confidence: 99%

Mechanical and thermal insulation properties of carbon fibre-reinforced carbon aerogel composites

Feng

Liu

et al. 2022

Advances in Applied Ceramics

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Carbon fibre-reinforced carbon aerogel composites (C/CAs) were prepared by using polyacrylonitrile (PAN) and phenolic (PH) carbon precursor fibres as reinforcements, respectively, then impregnated with resorcinol-formaldehyde sol, aging, solvent exchanging, CO 2 supercritical drying and carbonization at 1000°C. The physical properties, structural morphology and mechanical and thermal insulation behaviour of the two kinds of composites were further compared. Pore structure analysis shows that the PH-based C/CAs have a larger specific surface area (438.92 m 2 •g −1 ) and richer mesoporous volume than the PAN-based C/CAs. Mechanical behaviour of the C/CAs has been changed, but the stronger enhancement effects belong to PAN-based C/CAs (compressive strength in xy and zdirections are 1.63±0.10 MPa and 1.22±0.19 MPa, bending strength is 3.62±0.50 MPa). However, the PH-based C/CA composites have relatively low thermal conductivities, ranging from 0.027 to 0.164 W•m −1 •K −1 between 25 and 1800°C.

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“…The materials thermo-physical properties presented in this section are derived from the work of Delgado Montes et al 36 concerning the Phenolic Nylon. The Carbon Phenolic properties are adapted from the work of Sutton et al, 37 while the PICA properties are adapted from Parmenter et al 38 and Tran et al 39 At the outer surface of an ablative TPS several phenomena take place: conduction inwards and radiation outwards of the incoming heat, but also sublimation of the charred material and blockage due to the mass transfer of material in the boundary layer. The cooling flux of Eq.…”

Section: Viic Ablative Tps Solutionsmentioning

confidence: 99%

Robust Multi-Disciplinary Optimization of Unmanned Entry Capsules

Ridolfi

Mooji

Dirkx

et al. 2012

AIAA Modeling and Simulation Technologies Conference

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Uncertainties in design variables and environmental factors are common in many engineering problems, and they must be taken into account when searching for robust optimal solutions. In robust multi-objective optimization it is common practice to optimize the average performance instead of the nominal objective functions. To compute average performance, and to determine the compliance of the solutions to the constraints, sampling is needed in a neighborhood of each individual and the performance of each sample point must be evaluated. This drives the computational cost of robust optimization up. In this paper we present a repository-based approach that reduces the number of evaluations needed during robust optimization. Unlike most of the approaches available to date, we introduce methods to keep the joint probability density function of the input variables intact when pre-existing points from the repository shall be used. This allows for cheap robustoptimization also in the presence of non-uniform uncertain-variable distributions. The robust optimization of unmanned entry capsules, considering continuous shape-variation models, aerothermodynamics, flight mechanics, and thermal protection system models at the same time is a valuable test-bed for the method presented here. In this paper we discuss the results of minimizing the mass of the capsules while maximizing the internal volume and the re-usability. We demonstrate that using a double-repository archive maintenance scheme it is possible to obtain accurate results and a reduction of the computational cost that is close to 70%, if compared to classical sampling-based methods for robust optimization. The analysis of robust-optimal entry capsules demonstrates that there are design conditions for which small and fully reusable capsules for unmanned entry from low Earth orbits perform as well as capsules with ablative materials, also under uncertainties.

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Compressive Response of Lightweight Ceramic Ablators: Phenolic Impregnated Carbon Ablator

Cited by 35 publications

References 7 publications

Effect of microstructure on the thermal conductivity of disordered carbon

Effect of microstructure on the thermal conductivity of disordered carbon

Mechanical and thermal insulation properties of carbon fibre-reinforced carbon aerogel composites

Robust Multi-Disciplinary Optimization of Unmanned Entry Capsules

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