Effective Permeability of Carbon Composites Under Reentry Conditions

Effective permeability of a porous carbon composite is computed using the direct simulation Monte Carlo technique. The microstructure of the carbon composite is synthetically generated using an in-house solver. Permeabilities obtained using synthetic microstructures of the precursor (carbon fibers) is compared to two independent experimental dataset and good agreement is observed. An approach to digitally infuse matrix into the precursor is proposed. Comparison of the permeability for the full composite (carbon fibers with matrix) with experimental data demonstrates good agreement indicating that representative microstructures generated digitally can be used to compute and predict effective permeability of porous carbon composites. Simulations of gases penetrating the full composite are performed, and an intrinsic material permeability (Ko) of 11.866 × 10−11 m2, and a Klinkenberg constant (b∗) of 5.655 × 10−8 that is only dependent on the temperature and the molecular weight of the gaseous species is obtained.

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Influence of sol–gel derived silica-based interfacial coatings on the mechanical properties of carbon–carbon composites

Carbon ◽

10.1016/s0008-6223(02)00387-1 ◽

2003 ◽

Author(s):

S Dhakate

Keyword(s):

Mechanical Properties ◽

Sol Gel ◽

Carbon Composites

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Effects of contact gap on nondestructive evaluation using magnetic measurement for ferromagnetic steel

International Journal of Applied Electromagnetics and Mechanics ◽

10.3233/jae-209411 ◽

2020 ◽

Vol 64 (1-4) ◽

pp. 969-975

Author(s):

Hiroaki Kikuchi ◽

Yuki Sato

Keyword(s):

Magnetic Flux ◽

Nondestructive Evaluation ◽

Effective Permeability ◽

Magnetic Circuit ◽

Magnetic Measurement ◽

Air Gap ◽

Motive Force ◽

Hysteresis Curve ◽

Evaluation Technique ◽

Ferromagnetic Steel

We investigated effects of contact gap on magnetic nondestructive evaluation technique using a magnetic single-yoke probe. Firstly, we evaluated hysteresis curves and impedance related to permeability of the material measured by a single-yoke probe, when an air gap length between the probe and specimens changes. The hysteresis curve gradually inclines to the axis of the magneto-motive force and magneto-motive force at which the magnetic flux is 0 decreases with increasing the gap length. The effective permeability also decreases with increasing the gap thickness. The incremental of gap thickness increases the reluctance inside the magnetic circuit composed of the yoke, specimen and gap, which results in the reduction of flux applying to specimen.

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