Vibration analysis of asymmetric sandwich rotating FG porous discs coated with agglomerated nanocomposite facesheets

The present research conducts free vibration analysis of annular rotating discs made from functionally graded porous materials, and nanocomposite reinforced carbon nanotubes facesheets. Pores distribution in the porous core is considered based on three different patterns, namely Nonsymmetric, Symmetric, and Monotonous ones across the thickness, and also, carbo nanotube dispersion in the facesheets is investigated randomly by considering their agglomeration effect. Kinematic relations of the mentioned structure regarding the shear deformation effects and based on the first-order theory are described, and then, variations of strain and kinetic energies by considering rotation via the calculus variation method are calculated. To extract the governing motion equations and associated boundary conditions, Hamilton's principle is employed, and then they are solved with the aid of the generalized differential quadrature method. After ensuring the correctness of the results obtained from the scripted code by comparing them in the simpler state with the previous research, the effect of different parameters such as pores’ distribution patterns, carbon nanotubes dispersion patterns and their agglomeration, core and face sheets thickness, and other parameters on the natural frequencies of the structure is investigated. Considering the obtained results, it can be found that increasing the porosity leads to a slight increment in the natural frequencies, generally, and increasing the carbon nanotubes’ mass fraction leads to significant enhancement in them. The outcomes of this study can be used in different industries, such as aerospace, military, and marine industries.