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The present study investigates vibrational behavior of a porous conical hollow rotor. Inner and outer rotor surface, sensor, and actuator strips made of piezoceramic are modeled and positioned, which are symmetrically distributed in the circumferential direction. Kinetic and potential energies were computed considering the effects of Coriolis and centrifugal force. Modeling of the system has been carried out assuming classical theory and using Lagrange approach for simple-supported boundary conditions. Also, the relations of piezoceramic and three types of porosity attend in equilibrium equations. The discretization of kinetic and potential energies using displacement field which is defined as double mixed series based on independent mode shape and time function leads to obtaining the equations in form of ordinary differential. To calculate the natural frequencies, the equations were converted to a special form of state space model. The correctness of the study is examined by comparing it with similar study results. The most consequential parameters affecting the forward and backward natural frequency, such as type and porosity coefficient, size, number, and thickness of piezoceramic, and the rotor angular velocity, are researched. The results demonstrate that the effect of porosity coefficient in various longitudinal modes on natural frequency is different. [ABSTRACT FROM AUTHOR]

This investigation analyzes the effects of internal static fluid on the free vibrational behavior of joined shells made of carbon nanotube (CNT) fiber‐reinforced composite. Various types of functionally graded CNTs composite with temperature dependence are considered. Classic shell theory and Love's assumptions combined with Hamilton's principle are used to obtain motion equations. Bernoulli equation, velocity potential, and impermeability condition are employed to the coupling effects of fluid pressure with motion equations of shells. Continuity conditions in the joint point of conical and cylindrical sections are supposed to couple equations of two parts. The generalized differential quadrature (GDQ) method is employed to solve equations for various boundary conditions. Experimental modal tests on a sample made by the 3-D printer and prior others' research are used to validate the accuracy of results. Consequently, parametric studies are expressed, such as longitudinal and circumferential mode numbers, semi-vertex angle, distributions of CNTs, CNTs fraction volumes, fluid density, shell thickness, and operating temperature. According to the results, although fluid decreases the frequency generally, the process of changing frequency in terms of other parameters is similar. [ABSTRACT FROM AUTHOR]