The thermo-mechanical behavior of cometary nuclei

Miscellaneous · Sun Jan 01 00:00:00 EST 1989

OSTI ID:6741926

Green, J R

The thermo-mechanical behavior of cometary nuclei is investigated in terms of the properties of the porous ice composing them. The time-dependent thermal gradients and the material properties dictate the thermal stress response and possible fracture. Thermal conductivity, specific heat, coefficient of thermal expansion, Young's modulus, and Poisson's ratio are studied analytically as functions of porosity and composition. More extensive numerical calculations, employing the method of finite elements, yield the thermal conductivity as a function of porosity, pore shape, pore size, ice composition, pore vapor composition, pore orientation with respect to heat flow, pore size distribution, pore packing geometry, grain-grain interface size, and heat transport mechanism. Numerical techniques are employed to simulate the large-scale thermal and stress response of two-dimensional, planar comet surface layers. The thermal and stress profiles are calculated as functions of porosity, pore shape, and presence of pore space vapor. The numerical results are compared with analytical results for the development of thermal stress in a sphere under the same conditions. Fracture mechanics calculations of Griffith crack propagation are employed to investigate the occurrence of catastrophic fracture.

• Research Organization: Texas Univ., Austin, TX (USA)
• OSTI ID: 6741926
• Resource Relation: Other Information: Ph.D. Thesis
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
COMETS
MATHEMATICAL MODELS
MECHANICAL PROPERTIES
THERMODYNAMICS
ELASTICITY
FINITE ELEMENT METHOD
HEAT TRANSFER
SPECIFIC HEAT
SPHERES
TEMPERATURE DISTRIBUTION
THEORETICAL DATA
THERMAL CONDUCTIVITY
THERMAL EXPANSION
THERMAL STRESSES
DATA
ENERGY TRANSFER
EXPANSION
INFORMATION
NUMERICAL DATA
NUMERICAL SOLUTION
PHYSICAL PROPERTIES
STRESSES
TENSILE PROPERTIES
THERMODYNAMIC PROPERTIES
640107* - Astrophysics & Cosmology- Planetary Phenomena