Modal properties of beams and plates on resilient supports with rotational and translational complex stiffness

For beam and plate vibrations, energy dissipation may be mostly attributed to internal damping inside the structure and external damping at the supports. Surface damping treatment is one of the most effective tools to control vibrations of beam and plate in general. Sometimes it is not always desirable, however, to apply this damping treatment, for practical reasons. In such cases, one must rely on the damping treatment at the supports. In this presentation, the effects of damped compliant boundary conditions on modal parameters are investigated for two types of continuous systems; an elastic beam and a circular plate. The impedances at the boundaries to translational and rotational motions are given by springs with complex stiffness. The governing equations are solved numerically to obtain the natural frequencies and modal loss factors. Numerical results are represented in dimensionless terms, based on which a procedure of selecting the support parameters is illustrated to obtain desirable modal properties. (C) 1996 Academic Press Limited