Thermoforming is one of the most versatile and economical processes available for shaping polymer products. To improve the quality of final products, the temperature difference between surface and center of sheet should be continuously minimized. But, the temperature difference between surface and center of sheet can not be freely reduced because of low thermal conductivity of sheet materials. In this paper, an analysis model was developed under the condition that the inputted heat flux was expressed by an exponential function form. In the following step, an optimal design was carried out using a 3rd order polynomial. The optimal results show that the developed method can be used to reduce the temperature difference between surface and center of sheet by adjusting the parameter of time-dependent heat flux.
This paper describes vibration suppression of the flexible cantilever beams using shunted electromagnetic transducer. The proposed system consists of a coil attached on a cantilever and a permanent magnet placed under the bottom of the coil, and both ends of the coil were connected to the parallel resonant RLC shunt circuit. The dynamic model of cantilever beam with shunted electromagnetic damper was theoretically formulated and used to compare the analytic predictions with the experimental results. The vibration and damping characteristics of the flexible beams with the electromagnetic shunt damper were investigated by tuning the circuit parameters. Also, the effect of the magnetic intensity on the shunt damping was studied with the variation of the gap between the aluminum beam and the permanent magnet. Presented results show that the electromagnet shunt damper has good vibration reduction effect, and it can be successfully applied to reduce the vibration of the flexible structures.
Obtaining a uniform thickness of the final product using thermoforming is difficult, and the thickness distribution depends strongly on the distribution of the sheet temperature. In this paper, the time-dependent temperature distribution of the total sheets in the storing process was studied because the temperature after the storing process is the initial temperature of the preheating process. An analysis code for simulating the storing process was developed under the condition that the thermal conductivity caused by contact resistance between sheets was assumed as a large value. In this study, the number of sheets in the storing room was adjusted for finding out the effect of it. The analysis results show that maximum temperature difference between sheets was significantly different when adjusting the number of sheets in the storing room. The temperature distribution of the total sheets and the method for analysis in this study will be used to optimize the storing process for higher quality of final products.
The Ionic Polymer-Metal Composites (IPMC) actuator as electro-active polymers is well known for the fast and flexible bending actuation in the electric fields. In this paper, the IPMC actuator is fabricated and designed for realization of biomimetic flapping motion of dragonflies. The resonant frequency of a wing of anisoptera(dragonfly) was calculated by using finite element method and experimental frequency response function. Flapping motion of zygoptera(dragonfly) was considered in resonant frequency of the designed wing structure. The experimental results show that the IPMC wing structure of dragonfly has a good flapping performance in resonant frequency.
Based on the Matlab/Simulink module modeling for Fuel Cell Hybrid Electric Vehicle was carried out, which is comprised of the fuel cell stack model, a DC/DC converter model, a battery model, a motor model, avehiclemodel and a driver model, and Hybrid Control Unit(HCU) was developed. The HCU control strategy also incorporates regenerative braking and recharge for battery capacity recovery. Vehicle speed effect is evaluated in New Europe Driving Cycle. The simulation result that the control strategy implemented by HCU is achievable, and which proves that the mode of Start, Accele_FCBat, Cruise, RE_Brake, Power_FC and Pause operate sequently as well as reliably.
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