Khamidullin

In this paper the authors propose improved formulas for calculating coefficients of transfer matrix in the presence of damping. The authors consider a classical damping which means the damping matrix is proportional to the stiffness matrix. These formulas are designed for large finite-element models. Preliminary determination of the lower bound for natural frequencies and oscillation modes is expected. Approximate formulas are used only to calculate coefficients of obtained bending modes. In the revised formula contribution of higher vibration tones is taken into account; corrections for both real and imaginary parts of coefficients of the transfer matrix were also found. Contribution of rejected vibration tones is considered to be static, but within a given range of frequencies in the lower part of the spectrum accuracy is quite acceptable, and the effect of correction is significant.