Accession Number : ADA334876
Title : Elastothermodynamic Damping in Composite and Cracked Media
Descriptive Note : Final rept.
Corporate Author : AIR FORCE RESEARCH LAB BOLLING AFB DC
Personal Author(s) : Bishop, Joseph E.
PDF Url : ADA334876
Report Date : DEC 1995
Pagination or Media Count : 165
Abstract : When a composite material is subjected to a stress field, different regions undergo different temperature fluctuations due to the well-known thermoelastic effect. As a result irreversible heat conduction occurs, and entropy is produced which is manifested as a conversion of mechanical energy into heat. Moreover, the changes in temperature produce a thermal strain that is out of phase with the stress, thus converting mechanical energy into heat, i.e. work is lost. We define this process as elastothermodynamic damping. Herein, using the linear one-way coupled theory of elastothermodynamic relaxation, the elastothermodynamic damping of composite and cracked media is examined. Two equivalent descriptions of elastothermodynamic damping are first established: (1) the mechanical description and (2) the entropic description. An integral-transform technique is then developed to solve for the temperature field of a general composite medium with arbitrary heat generation. With this solution, a general expression for the damping of the composite material is derived.
Descriptors : *THERMODYNAMICS, *COMPOSITE MATERIALS, *CRACKS, *ELASTIC PROPERTIES, *DAMPING, STRESSES, COUPLING(INTERACTION), LINEAR SYSTEMS, MECHANICAL PROPERTIES, THESES, THERMAL CONDUCTIVITY, HEAT, THERMAL STRESSES, ENTROPY, MECHANICAL ENERGY, THERMOELASTICITY.
Subject Categories : Laminates and Composite Materials
Distribution Statement : APPROVED FOR PUBLIC RELEASE