Modeling the thermal properties and processing of composite materials

Miscellaneous · Wed Jan 01 00:00:00 EST 1992

OSTI ID:6268474

Pitchumani, R

The manufacture of partially cured, thermoset matrix composite systems is modeled. A generalized analysis, applicable to almost all the fiber-resin systems encountered in practice, is carried out in terms of four key dimensionless groups formed of the process and the product parameters - (1) the Damkohler number (K(sub o)) which is a relative measure of the conduction and the reaction time scales, (2) the dimensionless activation energy (E(sub o)), (3) the adiabatic reaction temperature (B(sub o)) which represents the temperature rise potential in the composite due to the heat of the cure reaction, and (4) the Biot number (B(sub i)) which characterizes the post-cure convective cooling of the composite product. Optimal cure cycles which yield a homogeneous cure in the composite, are obtained as a function of the dimensionless parameters. Design plots for the optimal cure temperature and duration are presented. Their use in practical situations is illustrated in the context of a commercially available graphite-epoxy prepreg from Hercules, which is widely used in the aerospace industry. The thermal properties of the composite namely, the transient thermal diffusivity and the steady state thermal conductivity, are essential parameters in the process modeling studies, as well for the design of composite materials for several high temperature applications. Transient heat conduction in fibrous composites is investigated with the aim of devising a criterion for the validity of the analysis of composite materials as homogeneous media having the effective thermal properties. A homogeneity criterion based on the composite thickness is derived in terms of the fiber volume fraction and the fiber diameter. The criterion, which is the first of its kind for fibrous composites, is valid in the practical range of composite parameters. An analytical means for evaluating the effective thermal diffusivity is also presented.

• Research Organization: Carnegie-Mellon Univ., Pittsburgh, PA (United States)
• OSTI ID: 6268474
• Resource Relation: Other Information: Ph.D. Thesis
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
COMPOSITE MATERIALS
MATHEMATICAL MODELS
THERMODYNAMIC PROPERTIES
MATRIX MATERIALS
PROCESSING
DESIGN
FIBERS
GRAPHITE
HEAT TRANSFER
REINFORCED MATERIALS
RESINS
THERMAL CONDUCTIVITY
THERMAL DIFFUSIVITY
CARBON
ELEMENTAL MINERALS
ELEMENTS
ENERGY TRANSFER
MATERIALS
MINERALS
NONMETALS
ORGANIC COMPOUNDS
ORGANIC POLYMERS
PETROCHEMICALS
PETROLEUM PRODUCTS
PHYSICAL PROPERTIES
POLYMERS
360606* - Other Materials- Physical Properties- (1992-)
360601 - Other Materials- Preparation & Manufacture