Volume 16, Issue 1 (January 1988)

    An Experimental Technique for Determining a Measure of Structural Damping

    (Received 27 January 1987; accepted 22 May 1987)

    CODEN: JTEOAD

      Format Pages Price  
    PDF Version 9 $25   ADD TO CART


    Abstract

    An experimental procedure for the determination of structural damping in a material specimen at low frequencies (<20 Hz) and low strain amplitudes (<10−5) is presented. The experimental apparatus entails a beam specimen supported under free-free boundary conditions and vibrated in first-mode flexural resonance. All experiments were carried out in vacuum at frequencies near 20 Hz, and data were automatically acquired using a system of electronic equipment. A measure of structural damping was obtained by reducing the acquired data using a linearized logarithmic decrement technique. Damping results are presented in the form ψ = Δ W/W, where ΔW is the energy dissipated during each loading cycle and W is the maximum stored energy.

    Experimental results discussed concern the structural damping of the following specimens: 6061-T6 aluminum, 6061 (annealed) aluminum, and 0 and 90 deg orientation continuous fiber P55Gr/6061A1 (graphite/aluminum) metal matrix composite. Damping values were determined for strain amplitudes of 6 × 10−6 to 20 × 10−6 and displayed an experimental scatter of 5 to 10%. An experimental technique to quantify extraneous apparatus losses is proposed, which estimates these losses to be approximately 10% of the measured damping value.


    Author Information:

    Wren, GG
    Mechanics and Materials Center and Department of Aerospace Engineering, Texas A&M University, College Station, TX

    Kinra, VK
    Mechanics and Materials Center and Department of Aerospace Engineering, Texas A&M University, College Station, TX


    Stock #: JTE11054J

    ISSN: 0090-3973

    DOI: 10.1520/JTE11054J

    ASTM International is a member of CrossRef.

    Author
    Title An Experimental Technique for Determining a Measure of Structural Damping
    Symposium , 0000-00-00
    Committee D30