Yun-De Shen

Vibration and Damping Analysis of Composite Fiber Reinforced Wind Blade with Viscoelastic Damping Control

Composite materials are increasingly used in wind blade because of their superior mechanical properties such as high strength-to-weight and stiffness-to-weight ratio. This paper presents vibration and damping analysis of fiberreinforced composite wind turbine blade with viscoelastic damping treatment. The finite element method based on full layerwise displacement theory was employed to analyze the damping, natural frequency, and modal loss factor of composite shell structure. The lamination angle was considered in mathematical modeling. The curved geometry, transverse shear, and normal strains were exactly considered in present layerwise shell model, which can depict the zig-zag in-plane and out-of-plane displacements. The frequency response functions of curved composite shell structure and wind blade were calculated. The results show that the damping ratio of viscoelastic layer is found to be very sensitive to determination of magnitude of composite structures. The frequency response functions with variety of thickness of damping layer were investigated. Moreover, the natural frequency, modal loss factor, and mode shapes of composite fiber reinforced wind blade with viscoelastic damping control were calculated.

High-Thrust Linear Actuator Based on Double Corner-Pole Airgaps for Proportional Relief Valve

This letter presents a high-thrust linear actuator for use in a proportional relief valve, based on double corner-pole airgaps formed by the structure of welding sleeve and step armature. The magnetic flux through the double corner-pole airgaps are divided into three parts of two radial fluxes (Φ1, Φ3) and one axial flux (Φ2), resulting in a linear characteristic with high-thrust force on the armature of the actuator. Parameter improvement in the limited space is analyzed based on modeling, and optimized results for a prototype actuator were obtained. The experimental and simulation results agree well. The prototype actuator can produce a thrust force of 110 N with a rated power of 12 W, and is linear within 4%, with 2% hysteresis over the displacement range of 0.8 to 2.3 mm. The force step response time of the actuator reaches 51 ms, and the force frequency response (-3 dB) reaches 36 Hz for a displacement of 1.5 mm.

Vibration Analysis of Cylindrical Sandwich Aluminum Shell with Viscoelastic Damping Treatment

This paper has applied the constrained viscoelastic layer damping treatments to a cylindrical aluminum shell using layerwise displacement theory. The transverse shear, the normal strains, and the curved geometry are exactly taken into account in the present layerwise shell model, which can depict the zig-zag in-plane and out-of-plane displacements. The damped natural frequencies, modal loss factors, and frequency response functions of cylindrical viscoelastic aluminum shells are compared with those of the base thick aluminum panel without a viscoelastic layer. The thickness and damping ratio of the viscoelastic damping layer, the curvature of proposed cylindrical aluminum structure, and placement of damping layer of the aluminum panel were investigated using frequency response function. The presented results show that the sandwiched viscoelastic damping layer can effectively suppress vibration of cylindrical aluminum structure.

Force characteristic of a magnetic actuator for separable electric connector based on conical airgap

This article presents a magnetic actuator for use in a separable electric connector based on conical airgap. The magnetic flux lines in conical airgap are almost vertical to the edge face of the yoke and armature, showing that the actual flux length in conical airgap is smaller than the axial stroke, which reduces magnetic reluctance over large stroke. Parameter improvement is analyzed based on modeling, and optimal results of the magnetic actuator are adopted to improve the rate of force to volume. The experimental results show that there is friction force of 10–12 N existing in the moving armature of the prototype, and the nominal value is in accordance with the simulation one. The results show that the design of conical airgap in the magnetic actuator is available to improve the initial force and reliability of the separating process and has the advantages of compact structure, short transmission, high reliability, large force with 50 N at the initial displacement of 2.5 mm, and fast response with 16.5 ms over the traditional actuator.

Optimal Heater Control with Technology of Fault Tolerance for Compensating Thermoforming Preheating System

The adjustment of heater power is very important because the distribution of thickness strongly depends on the distribution of sheet temperature. In this paper, the steady state optimum distribution of heater power is searched by numerical optimization in order to get uniform sheet temperature. In the following step, optimal heater power distribution with a damaged heater was found out using the technology of fault tolerance, which will be used to reduce the repairing time when some heaters are damaged. The merit of this work is that the design variable was the power of each heater which can be directly used in the preheating process of thermoforming.

Performance Prediction of Large Scale Vacuum Furnace Using Thermal Analysis

A method using thermal analysis has been recommeded to substitute the original method what was based on trial and error for manufacturing a high performance, low cost product. At first, a large scale vacuum furnace was modeled according to a real product, and it was simulated using the material properties in a previous study under the condition of having argon ambient gas. Finally, the performance of the large scale vacuum furnace was discussed using the obtained results of analysis. The method in this study will be used to produce an energy efficient, low cost product using optimization technique under the condition of fully satisfying users design requirements.

Vibration Suppression of Flywheel AMB System with Flexible Rotor Using Backstepping Control

This paper discusses the model vibration suppression of an AMB system with flexible rotor via additional back stepping controller. The key problem in the flexible rotor system is how to obtain a precise model that the gyroscopic effect is considered and design a suitable controller based on the reduced-order model to suppress critical vibration of actual system. Firstly, the vibration modes and mode shapes are analyzed using finite element method(FEM). Secondly, the AMB flexible rotor is stabilized with a PID and the mode identification is carried for validating the FEM model. Third, the cholesky decomposition is introduced for the mode separation and a back stepping controller for the flexible model control is designed based on the reduced order model. The effectiveness of the reduced-order model and the designed back stepping controller are verified through the simulation result.

Piezoelectric Material Based Energy Generator Using Bistable Cantilever Beam

Recently, the vibration induced by nonlinear energy harvesting systems has been studied. This paper describes an energy generator employing bistable piezoelectric cantilever beam. The system consists of a piezoelectric material attached on cantilever, a permanent magnet fixed at tip of the cantilever beam and two magnets placed at both side of the tip magnet. The bistable phenomenon was investigated by changing the gap between the tip magnet and side magnet. The trend of output energy from bistable piezoelectric cantilever beam was studied experimentally by considering the different gap distance and different initial displacement. As shown in results, the bistable cantilevered beams show a wider range of power than the linear vibrating system.

Time-dependent Optimal Heater Control Using NURBS and RSM

Thermoforming is one of the most versatile and economical processes available for shaping polymer products. To improve the competitive power of the products, the manufacturing fee should be continuously reduced. But, the required heat can not be freely reduced because of the temperature difference between surface and center of the sheets. In this paper, an optimal design using NURBS and RSM was carried out for decreasing the required heat. NURBS were used to design shapes for the time-dependent variation of heater power inputs, and D-optimal method was used to select experimental points to construct the response surfaces. The optimal results show that the developed method in this study can be used to reduce the required heat in the forming temperature range by the end of the heating process.

Notice of Retraction A Study on Steam Generator for Domestic Steam Cleaner with Cartridge Heater

The steam generation mechanism is the key technology of the domestic steam cleaner. Not only the weight and price of a steam cleaner but also the performance of a steam generation mechanism must be considered to improve the competitive power of the products. In this study, a new steam generator which using a cartridge heater was recommended for compensating the drawback of the spray boiling steam generator. The experimental and numerical results show that the warm-up time, the volume and weight of the cartridge steam generator were much smaller than the spray boiling steam generator. The experimental and numerical method in this study can be used to develop a high performance, low cost steam generator for the domestic steam cleaner.