Free vibrations of layered beam with non-rectangular cross-section composed of viscoelastic layers

The paper deals with two methods of calculating of the eigenfrequencies and the logarithmic decrement for two-layer T-beam composed of viscoelastic stiffness-comparable layers. One of the methods is developed within the linear theory of (visco)elasticity by assuming continuity conditions of forces (instead of stresses) between adjoining layers. Second method is based on Kirchhoff hypothesis and Rayleigh method. A comparison of the methods has been presented and simple, useful relationships for calculation of the logarithmic decrement have been established.