STP1169

    Irreversible Heat Transfer as a Source of Thermoelastic Damping

    Published: Jan 1992


      Format Pages Price  
    PDF (448K) 30 $25   ADD TO CART
    Complete Source PDF (11M) 30 $135   ADD TO CART


    Abstract

    Some 50 years ago, Zener considered transverse vibrations of a homogeneous, isotropic, and thermoelastic beam. Invoking the Thomson effect, he observed that the tensile side cools while the compressional side heats up resulting in irreversible heat transfer across the neutral axis. This led him to postulate the existence of thermoelastic damping that he modeled in terms of standard anelastic solids. With the advent of metal-matrix composites, there is a need for a theory of thermoelastic damping in engineering materials that are inherently anisotropic and heterogeneous. Unfortunately, Zener's simple model cannot be easily extended to composite materials; this defines the objective of this paper.

    Taking the Second Law of Thermodynamics as our starting point, we calculate the thermoelastic damping from the entropy created due to irreversible heat transfer. The thermal currents can be set up either as a result of an inhomogeneous stress field in a homogeneous medium, or a homogeneous stress field in an inhomogeneous medium, or both. The exact theory is equally applicable to monolithic or composite materials. As illustrative examples, we solve three boundary value problems: 1. The damping of an isotropic and homogeneous beam undergoing flexural vibration. 2. The interface damping resulting from the longitudinal vibrations of two rods in thermomechanical contact. 3. The damping in a thermoelastic inclusion in a rod subjected to uniaxial stress.

    Keywords:

    material damping, internal friction, internal stress, thermoelastic damping, metal-matrix composites, Second Law of Thermodynamics, irreversible heat transfer, entropy production, mechanical properties


    Author Information:

    Kinra, VK
    Professor of Aerospace Engineering and associate director, Center for Mechanics of Composites, Texas A&M University, College Station, TX

    Milligan, KB
    Graduate research assistant, Texas A&M University, College Station, TX


    Paper ID: STP17957S

    Committee/Subcommittee: E28.10

    DOI: 10.1520/STP17957S


    CrossRef ASTM International is a member of CrossRef.