1989 Volume 38 Issue 429 Pages 630-636
In this paper, the torsional stress and torsional rigidity of a two-layer beam coated with viscoelastic material were analyzed exactly, and an expression for the composite loss factor of the beam in torsion was presented based on the analytical results.
The numerical results obtained are summerized as follows.
(1) The maximum shear stress arose at the upper or lower interface between two layers, whichever side has low shear strength. The limitation of the beam composition in such case was obtained in conjunction with the thickness ratio and the shear modulus ratio of viscoelastic layer to elastic one.
(2) The scale rule for the composite loss factor does not hold exactly in a torsional condition, but approximately hold for the limited ranges of the thickness of elastic layer, the thickness ratio and the shear modulus ratio.
(3) Both of the composite loss factors in torsion and in bending for the two-layer beams having the same beam composition were nearly equal except that the thickness ratio was over unity.
