Zhengliang Wang

Bio: Zhengliang Wang is an academic researcher from Zhejiang Wanli University. The author has contributed to research in topics: Boundary value problem & Instability. The author has an hindex of 1, co-authored 1 publications receiving 12 citations.

Vibration of spinning functionally graded nanotubes conveying fluid

Abstract: As a first attempt, the vibration and stability analysis of magnetically embedded spinning axially functionally graded (AFG) nanotubes conveying fluid under axial loads is performed based on the nonlocal strain gradient theory (NSGT). A detailed parametric investigation is conducted to elucidate the influence of key factors such as material distribution type and size-dependent parameters on the divergence and flutter instability borders. Also, a comparative study is conducted to evaluate the available theories in the modeling of nanofluidic systems. The material characteristics of the system are graded along the longitudinal direction based on the power-law and exponential distribution functions. To accurate model and formulate the system, the no-slip boundary condition is considered. Adopting the Laplace transform and Galerkin discretization technique, the governing size-dependent dynamical equations of the system are solved. The backward and forward natural frequencies, as well as critical fluid and spin velocities of the system, are extracted. Besides, an analytical approach is applied to identify the instability thresholds of the system. Dynamical configurations, Campbell diagrams, and stability maps are analyzed. Meanwhile, it is concluded that, in contrast to the influence of nonlocal and density gradient parameters, the increment of strain gradient and elastic modulus gradient parameters expands the stability regions and alleviate the destabilizing effect of the axial compressive load.

Computer simulation via a couple of homotopy perturbation methods and the generalized differential quadrature method for nonlinear vibration of functionally graded non-uniform micro-tube

Abstract: In this paper, to improve the vibrational response of microstructures, the impact of the nonlinear modal analysis of axially functionally graded (AFG) truncated conical micro-scale tube including the thermal loading for the different type of cross sections such as uniform section, linear tapered section, convex section, the exponential section are studied that are applicable for various application, for example, the micro-thermal fins, macro-/micro-fluid-flow diffuser, fluid-flow nozzle, fluid-flow throat, micro-sensor, etc. The nonlinear equations are obtained applying Hamilton’s principles based on the modified couple stress to determine the size effect and Euler–Bernoulli beam theory considering the von-Karman’s nonlinear strain. The material combination varies along the tube’s length, denouncing the AFG tube made by metal and ceramic phases. The nonlinear equations are solved by applying a couple of homotopy perturbation methods (HPM) to calculating the nonlinear results and the generalized differential quadrature method (GDQM) to providing the initial conditions. The linear and nonlinear results presented the effect of various cross sections and other parameters on the micro-tube frequency that are valuable to design and manufacture the micro-electro-mechanical systems (MEMS).

Hygro–thermo–magnetically induced vibration of nanobeams with simultaneous axial and spinning motions based on nonlocal strain gradient theory

Abstract: In this paper, based on the nonlocal strain gradient theory (NSGT), the coupled vibrations of nanobeams with axial and spinning motions under complex environmental changes are modeled. A detailed parametric investigation is also performed to determine the effect of size-dependent parameters, boundary conditions, hygro–thermo–magnetic loads, axial and spin velocities on the dynamical behavior and stability regions of the system. Adopting the Galerkin discretization technique, the eigenvalue problem is solved, and natural frequencies, divergence and flutter instability thresholds of the system are extracted accordingly. The acquired outcomes are compared with the reported results in the literature. Besides, the accuracy of the numerical method is compared with analytical approaches and a good agreement is observed. The obtained results demonstrate that considering the nonlocal and hygro–thermal effects in modeling has destabilizing impacts on the dynamical response of the system. While imposing the strain gradient term and magnetic field leads to the enhancement of vibrational frequencies and enlargement of stability areas. In addition, it is concluded that in hygro–thermal environments, by ascending the spin velocity, instead of the occurrence of divergence instability, the system experiences the flutter conditions. Meanwhile, the attained outcomes indicated that the variation of spin velocity does not affect the flutter instability threshold of the system.