Campbell Diagrams of Some Advanced Composite Blades: A Comparative Analysis

Rotating blades are one of the most critical components of any gas turbine. These rotating structures are subjected to dynamic loads while operating in harsh thermal environmental conditions. Hence, the modal analysis of rotating blades at high temperatures is carried out to report the dynamic characteristics at the operating conditions and prevent consequent failures due to uncontrolled vibrations. In this article, such modal analysis is carried out to compare the dynamic characteristics of three advanced functionally graded sandwich blades with SUS304, Ti6Al4V, and IN718 as core materials and their respective functionally graded face-sheets with Si3N4 as the other component. The blades are assumed as 2D twisted rotating cantilevered shells located at an offset from the axis of rotation, resembling the blades located on the hub. The first-order-shear-deformation theory is used to establish the strain–displacement relationship. Material distribution is governed by power law distributions and Voigt’s homogenisation scheme. The governing equations are obtained using the Hamilton’s principle and solved using the finite element method and Block Lanczos algorithm to obtain the eigenvalues. Finally, the Campbell diagrams of the advanced composite blades rotating at moderate speeds are plotted, and the vibration characteristics of the three different blades are compared.