Project Title:
Effective Porosity of Rayon-Based Carbon-Phenolics
92-1-11.04-8900B NAS08-39833
Effective Porosity of Rayon-Based
Carbon-Phenolics
PDA Engineering
2975 Redhill Avenue
Costa Mesa, CA 92626
Douglas A. Marx (714-540-8900)
Abstract:
The effect of pore pressures resulting from the pyrolytic
decomposition of carbon-phenolics is to add an internal force on
the solid phase of the remaining char. The effective porosity
represents a measure of the area over which this pore pressure
acts as well as defining the area of the solid phase material over
which internal stresses are developed to counteract the pore
pressure. Tests have demonstrated that volume porosity is a poor
measure of the effective porosity. Also, in the presence of
confining boundary conditions, the effective porosity can vary
greatly due to the compressibility of the solid phase. In order to
perform precise thermostructural calculations of stresses and
strains, as well as accurate predictions of structural margins of
safety, both the magnitude of the pore pressure and the effective
porosity must be known. To date, laboratory data have failed to
isolate these two parameters from each other. Therefore, the
intent of this study is to design a test specimen that will
accurately measure the effective porosity in precharred specimens
of carbon-phenolic. This design test will be developed by
performing thermostructural analyses and a limited amount of
experimental testing. The project's main goal is to derive a test
methodology suitable for rayon-based carbon-phenolics. In
addition, the project will research how variations in pore
morphology influence the effective porosity.
Potential Commercial Application:
Potential Commercial Applications: A means to significantly
increase the reliability of carbon-phenolic rocket nozzle
structural components will be of particular value to NASA and to
the rocket nozzle industry that must contend with maintaining a
high degree of reliability and performance.
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