Dynamics of advanced rotating blades made of functionally graded materials and operating in a high-temperature field

Abstract

Problems involving the modeling and free vibration of pre-twisted rotating blades made of functionally graded materials (FGMs) and operating in a high-temperature field are considered. The blade, mounted on a rigid hub, is modeled as a thin-walled beam that incorporates the warping restraint and the pre-twist effects. As a result of the latter feature, an extension-twist elastic coupling is induced. Consistent with the concept of the FGM structures, the two constituent materials, ceramic and metal, experience a continuous variation across the beam wall thickness, and, as a result, the adverse effects featured by the standard laminated structures, such as delamination/debonding, are precluded to occur. Numerical results highlighting the effects of the extension-twist elastic coupling considered in conjunction with the volume fraction of the two constituent phases and of the thermal degradation of material properties on eigenfrequencies are presented, and pertinent conclusions are outlined. Comparisons of predictions, as well as validations of results against those obtained in some special cases, which are available in the specialized literature, are also supplied. In addition to a better understanding of the implication of incorporation of FGMs, the results of this research can be instrumental toward the reliable design of advanced turbomachinery blades that operate in a high-temperature environment.