star pdf file

oth stiffness and strength, and aging at cryogenic temperature while under load can alter the mechanical properties of pristine,
un-aged laminates made of IM7/PETI-5 material.
Author
Temperature Effects; Polymer Matrix Composites; Cryogenic Temperature; Compressive Strength
20030032245 NASA Glenn Research Center, Cleveland, OH, USA
A Thermodynamic Theory of Solid Viscoelasticity. Part 3: Nonlinear Glassy Viscoelasticity, Stability Constraints,
Specifications
Freed, Alan; Leonov, Arkady I.; Journal of the Mechanics and Physics of Solids; July 03, 2002, pp. 1-17; In English
Contract(s)/Grant(s): NCC3-752
Report No.(s): Rept-3/PT3; No Copyright; Avail: CASI; A03, Hardcopy
This paper, the last in the series, continues developing the nonlinear constitutive relations for non-isothermal,
compressible, solid viscoelasticity. We initially discuss a single integral approach, more suitable for the glassy state of
rubber-like materials, with basic functionals involved in the thermodynamic description for this type of viscoelasticity. Then
we switch our attention to analyzing stability constraints, imposed on the general formulation of the nonlinear theory of solid
viscoelasticity. Finally, we discuss specific (known from the literature or new) expressions for material functions that are
involved in the constitutive formulations of both the rubber-like and glassy-like, complementary parts of the theory.
Author
Nonlinearity; Thermodynamics; Viscoelasticity; Solids; Nonequilibrium Thermodynamics; Glass; Stability
28
PROPELLANTS AND FUELS
Includes rocket propellants, igniters, and oxidizers; their storage and handling procedures; and aircraft fuels. For nuclear fuels see 73
Nuclear Physics. For related information see also 07 Aircraft Propulsion and Power; 20 Spacecraft Propulsion and Power; and 44
Energy Production and Conversion.
20030031357 NASA Goddard Space Flight Center, Greenbelt, MD, USA
Inconsistent Definitions of the Pressure-Coupled Response and the Admittance of Solid Propellants
Cardiff, Eric H.; [2003]; 7 pp.; In English; No Copyright; Avail: CASI; A02, Hardcopy
When an acoustic wave is present in a solid propellant combustion environment, the mass flux from the combustion zone
oscillates at the same frequency as the acoustics. The acoustic wave is either amplified or attenuated by the response of the
combustion to the acoustic disturbance. When the acoustic wave is amplified, this process is called combustion instability. The
amplification is quantitatively measured by a response function. The ability to predict combustion stability for a solid
propellant formulation is essential to the formulator to prevent or minimize the effects of instabilities, such as an oscillatory
thrust. Unfortunately, the prediction of response values for a particular propellant remains a technical challenge. Most
predictions of the response of propellants are based on test data, but there are a number of questions about the reliability of
the standard test method, the T-burner. Alternate methods have been developed to measure the response of a propellant,
including the ultrasound burner, the magnetic flowmeter and the rotating valve burner, but there are still inconsistencies
between the results obtained by these different methods. Aside from the experimental differences, the values of the
pressure-coupled responses obtained by different researchers are often compared erroneously, for the simple reason that
inconsistencies in the definitions of the responses and admittances are not considered. The use of different definitions has led
to substantial confusion since the first theoretical treatments of the problem by Hart and McClure in 1959. The definitions and
relations derived here seek to alleviate this problem.
Derived from text
Solid Propellant Combustion; Solid Propellants; Combustion Stability; Acoustics; Coupled Modes; Electrical Impedance;
Pressure Oscillations
43