3-D vibration analysis of circular rings with sectorial cross-sections

The free vibration characteristics of circular rings with sectorial cross-section are studied based on the three-dimensional (3-D), small strain, linear elasticity theory. The complete vibration spectrum has been obtained by using the Ritz method. A set of three-dimensional orthogonal coordinates composing of the polar coordinates (r,θ) at the origin of the sectorial cross-section and circumferential coordinate ϕ around the ring is developed to describe the variables in the analysis. Each of the displacement components is taken as a triplicate series: two Chebyshev polynomial series, respectively, about the r and θ coordinates, and a trigonometric series about the ϕ coordinate. Frequency parameters and vibration mode shapes are computed by means of the displacement-based extremum energy principle. Upper bound convergence of the first eight frequency parameters accurate to at least five significant figures is presented. The effect of radius ratio, subtended angle, and initial slope angle on frequency parameters is investigated in detail. All major modes such as flexural modes, thickness-shear modes, stretching modes, and torsional modes, etc. are presented in the paper. The present results may serve as a benchmark reference to validate the accuracy of various approximate theories and other computational techniques for the vibration of circular rings.