Determination of the Complex Shear Modulus of Damping Materials by the Composite Beam Test Method

Abstract

This investigation presents a method determining the complex shear moduls of damping materials from torsional resonance test of a rectangular covered rod bonded damping layer materials on both sides of the rod. This method (Composite Beam Test Method) provides an available expression with such determination, which is based on an exact solution of a torsional rigidity of the three-layered rod. The experimental results carried out for a commercially available damping rubber show reliable determination up to its transition temperature range. An error analysis for the covered rod, and also a sandwich rod with a damping core layer, clarifies that the resultant errors of the determined values of both rods greatly depend on the accuracy of both measured values of the thickness and shear modulus of each elastic layer. Furthermore, the error analysis clarifies that the sandwich rod is superior in this method to the covered rod due to the exceeding reduction of its resultant error in comparison to the one of the covered rod over wide range of the damping material constants.