Forced and free vibrational analysis of viscoelastic nanotubes conveying fluid subjected to moving load in hygro-thermo-magnetic environments with surface effects

Thermoelastic vibrations in electro-mechanical resonators based on rotating microbeams exposed to laser heat under generalized thermoelasticity with three relaxation times

The flutter characteristics of a truncated conical shell with variable thickness exposed to a supersonic fluid flow are studied in this study. The first-order shear deformation theory (FSDT) is employed to model the shell and the linear piston theory is utilized to evaluate the aerodynamic pressure. The boundary conditions and governing equations are formulated based on Hamilton’s principle. An exact solution is presented in the circumferential direction and the differential quadrature method (DQM) is hired to present an approximate solution in the meridional direction. A general two-parameter power-law equation is considered for thickness variation in the meridional direction and the effects of these coefficients on the flutter boundaries are examined. It is observed that utilizing the conical shells with uniform thickness is not an optimum design and to improve the aeroelastic stability of the conical shells it is better to increase the thickness of the shell from the small radius of the shell to the large one. As the novelty of the presented work, it can be claimed that it is the first attempt to examine the flutter characteristics of conical shells of nonuniform thickness and the results can be utilized to provide optimum designs for aerovehicles. 

Effect of variable thickness on the aeroelastic stability boundaries of truncated conical shells

A literary review related to micro/miniature heat pipes is presented ever since the introduction of the concept of micro heat pipe. Both the theoretical and experimental research of micro/miniature heat pipes, including single micro heat pipe, heat pipe array and flat miniature heat pipes, are reviewed respectively. The heat transfer limitations of micro/miniature heat pipes are also surveyed at the same time. In the end, the consistently recognized research conclusions and the difficulties and challenges in the micro/miniature heat pipes research are summarized. It is proved that the micro/miniature heat pipes are promising for the use of small - room heat dissipation such as the cooling of micro electronic apparatus.

Status and Recent Progress of Research on Micro/Miniature Heat Pipes

This article analyzes the forced and free vibrations of bi-directional functionally graded (BDFG) porous nanobeams under moving loads by considering the thickness effect based on the nonlocal strain gradient theory (NSGT). It is assumed that the material properties of the system are graded across the transverse and axial directions according to power and exponential laws, respectively. Various porosity models, including even, uneven, and asymmetric porosity distribution patterns, are considered to model the porosity effects. The dynamic equation of the system is derived by implementing the physical neutral surface concept. Analytical and numerical approaches are adopted to acquire the vibration response of the system. Mathematical closed-form expressions are provided for various dynamic phenomena, such as two types of cancelation, two types of resonance, maximum resonance, cancelation disappearance, and resonance disappearance. In addition, for the first time in this article, it is demonstrated that BDFG porous nanobeams under moving loads are prone to experience the double cancelation phenomenon. Several comparison studies with published data are conducted to validate the results. Also, comprehensive parametric studies are carried out to elucidate the impacts of system parameters such as thickness power index, axial gradient parameter, scale parameter ratio, axial force, porosity coefficient, and porosity distribution pattern on the dynamic magnification factor, critical load speed, and maximum free-response. The outcomes established that by considering the thickness effect, the stiffening behavior of the system is amplified depending on the slenderness ratio. Also, it is concluded that, among the considered porous models, the critical load speed for the system with an even porosity distribution is more dependent on the thickness power index. 

Size-dependent vibrations of bi-directional functionally graded porous beams under moving loads incorporating thickness effect

Analytical and parametric analysis of thermoelastic damping in circular cylindrical nanoshells by capturing small-scale effect on both structure and heat conduction

According to the characteristics of ploughing extrusion forming and the theory of metal cutting, the wear and damage mechanism, common wear and damage forms and causes of multi-tooth tools in ploughing extrusion forming are analyzed. Then, the correctness of the analysis of tool wear and damage mechanism and common wear and damage forms is verified by field cutting experiments. At the same time, the phenomena and causes of workpiece stagnation and cracks in the process of ploughing and extrusion forming were obtained through experiments. Finally, the reasonable processing parameters of ploughing and extrusion forming multi-tooth cutting tool were obtained.

Experimental research of ploughing extrusion forming multi-tooth tool wear and damage mechanism and workpiece defects

In order to research the ploughing extrusion angle influence on cutting performance and realize the virtual design and manufacture of ploughing-extrusion forming cutter, the plough-extrusion forming process of wick micro-groove structure was simulated by DEFORM-3D software. The micro-copper tube with diameter of 6 mm was simplified to 0.4 mm thick copper plate in this paper. In the simulation process, only the single parameter of tool extrusion angle was changed (45°, 60°, and 90°). The structure, stress and strain distributions of copper plate fins formed by three kinds of extrusion angle cutters were analyzed. It is concluded that the plough-extrusion cutting performance of 60 degree extrusion angle cutter is the best.

Hongyan Wang

Papers

Analytical and parametric analysis of thermoelastic damping in circular cylindrical nanoshells by capturing small-scale effect on both structure and heat conduction

Experimental research of ploughing extrusion forming multi-tooth tool wear and damage mechanism and workpiece defects

Simulation Research on Ploughing Extrusion Angle Influence on Machinability