The natural vibrations of a corrugated elastic orthotropic cylindrical shell with a directrix perpendicular to its edges that are free are examined Keywords: corrugated elastic orthotropic cylindrical shell, natural vibrations, momentless stress state, absence of bending stiffness Introduction. Many important research and technology problems involve study of the vibrations of and wave propagation in deformed solid media. These are in particular problems of seismic prospecting, aircraft construction, shipbuilding, instrument making, dynamics of power-engineering structures, etc. Rayleigh's work [28] was the first to study elastic surface waves. He discovered elastic waves propagating along the free boundary of a half-space and having amplitude quickly decreasing with depth. Such waves observed in elastic bodies of various geometries are commonly referred to as Rayleigh waves. Waves localized near the free boundary of a semi-infinite plate and waves propagating along a semi-infinite cylindrical shell and decaying with distance from the free end are of Rayleigh type too [7]. In a semi-infinite plate, according to a Kirchhoff-Love hypothesis, there exist independent planar and bending waves localized along the free boundary [2,3,6,21,22]. If the plate is curved, these two waves appear coupled, giving rise to new two (preferential bending and preferential tangential) oscillations localized at the edge [13][14][15]. Of special interest are problems on cylindrical shells of varying curvature. Such problems are solved using various analytic and numerical methods [1,9,10,24,[29][30][31][32]. The natural vibrations of a semi-infinite momentless cylindrical shell damped with distance from its free edge are examined in [5,12,16,17]. The natural vibrations of a cantilever corrugated orthotropic momentless cylindrical shell are studied in [18].The present paper is concerned with the natural vibrations of a corrugated (and closed) orthotropic momentless cylindrical shell with free edges. It is assumed that the generatrices are perpendicular to the edges and the squared curvature of the directrix can be expanded into a series: R k r r km km m m m -= ¥ = + + ae è ç ç ö ø ÷ ÷ å 2 2 0 1 2 / cos sin b r b ,where b is the directed arc length of the directrix. Note that the class of cylindrical shells under consideration includes closed cylindrical shells with free edges and arbitrary smooth directrices. In this case, k n s = 2 0 p / , where s is the total length of the directrix, n N 0 Î . We have derived dispersion equations and established asymptotic relationships between these equations and the dispersion equations for a shell structure consisting of countably identical open orthotropic circular cylindrical shells and an orthotropic strip plate and the dispersion equations for a corrugated semi-infinite orthotropic momentless cylindrical shell with free edge. We will present approximate values of the dimensionless natural frequencies and damping factors for cylindrical shells having lengths l = 5 and l = 15, directrices y a cx b c...