Abstract: The modal features of weakly-viscoelastic material structures for single-modulus materials are discussed in this paper. It is pointed out that the eigenvalues of these structures are the roots of a series of rational fraction polynomial equations. A theorem about the roots of these equations is proved in the paper. Based on it, some important conclusions about the modal features of weakly-viscoelastic material structures are drawn according to their dynamic behavior.

Key words: viscoelasticity, weakly-viscoelasticity, structural vi-bration, modal characteristics.