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In this article, theoretical modeling and vibration characteristics of a spinning double-blade beam assembly restricted by elastic supports are studied. Graphene nanoplatelet (GPL) reinforcement and porous foamed metal matrix are adopted to make up the assembly structure. Due to the nonuniformity of the porosity and graphene nanofillers, the material properties of the attached blades and beam are considered to change along the blade thickness and beam radius, respectively. They are obtained via the rule of mixture, the open-cell scheme and the Halpin-Tsai micromechanics model. These attached blades and beam are modeled in accordance with the Euler-Bernoulli beam theory and the Rayleigh beam theory, respectively. Via employing the Lagrange's equation, the equations of motion of the double-blade beam are derived. Then, the natural frequencies of the spinning nanocomposite double-blade beam are calculated by the substructure modal synthesis method and the assumed modes method. A detailed parameter analysis is performed to study the influences of dimension, distribution pattern and weight fraction of GPLs, distribution and coefficient of porosity, length and location of the blades, stiffness and location of supports, and spinning speed on the mechanical behaviors of the double-blade beam assembly. [ABSTRACT FROM AUTHOR]

This paper presents an investigation on vibration characteristics of graphene nanoplatelet (GPL) reinforced disk-shaft rotor with eccentric mass resting on elastic supports. The shaft is made of common metal material while the disk is made of graphene nanoplatelet reinforced material. The weight fraction of graphene nanoplatelets (GPLs) is assumed to vary smoothly and continuously along the thickness direction of the disk, which leads to a functionally gradient (FG) structure. The effective properties of the disk are determined via the Halpin-Tsai micromechanics model and the rule of mixture. In accordance with the Timoshenko beam theory and Kirchhoff plate theory, the governing equations which take into account gyroscopic effect due to rotation are derived by using the Lagrange equation. The substructure modal synthesis method and the assumed modes method are utilized to obtain the natural frequencies, and the Runge-Kutta method is adopted to solve the forced vibration response of the rotor system, where the centrifugal force and gravity of an eccentric mass in the shaft are considered as generalized forces. The present analysis is validated through comparison with both experiment and finite element (FE) results. A detailed parametric study is conducted to examine the effects of the rotating speed, GPL weight fraction, GPL distribution pattern, length-to-thickness ratio and length-to-width ratio of GPLs, disk position, disk dimension, and support stiffness on vibration behaviors of the nanocomposite disk-shaft rotor system. [ABSTRACT FROM AUTHOR]