介電致動高分子在崩潰電壓下與其材料可逆性的討論與研究

Abstract

近年來，由於介電致動高分子材料(dielectric electroactive polymers, DEAPs)具有良好的力學性質、高介電係數及低成本的特性，讓其在做為致動器的範疇中受到相當的注目。然而，介電致動高分子材料的驅動特性會受驅動電壓大小及其幾何尺寸上限制的影響；隨著電壓的上升，因所受靜電力增加而使上下電極逐漸靠近，若發生吸附效應則兩電極最終會貼合。若介電致動高分子材料厚度較薄，則可以降低驅動電壓，並提升材料的可靠度；材料可靠度的研究是近來重要的課題。本論文針對材料崩潰現象、吸附現象及其可逆性進行探討。實驗中給予一直流電壓，觀察電流及變形量隨時間與不同驅動電壓的變化情形。實驗結果顯示當電壓加至2000Ｖ時，會有大電流出現，象徵此時即為崩潰現象發生的時刻；並由已推知的條件判斷式可以得到崩潰現象會發生在吸附效應之前。本實驗同時經由逐漸增加電壓至1600V，再降回0V，觀察其材料的可逆與重複性，並對其遲滯效應做一些探討。另一方面，本論文也透過靜電及超彈性材料的力分析提出力電耦合的材料模型。

Recently, there has been growing interest in actuators by using dielectric electroactive polymers, DEAPs due to their attractive properties of mechanism, low cost and high dielectric constant. However, operating characteristics of DEAPs are affected by applied voltage and the size of DEAPs. With increases applied voltage, because of increasing electric force, compliant electrodes of actuator are gradually close to each other. If the thickness of DEAPs decreases, applied voltage can be lower and reliability can be improved. The researches of reliability are important issues today. In our experiments, we focus on and discuss breakdown phenomenon, pull-in effect and reversibility of DEAPs material. In the experiment, we apply a DC voltage to DEA actuator and observe the alterations of displacement and current with time and the increase of applied voltage. In our results, it was found that the largest current is observed by computer when applied voltage is 2000V. This result signifies that breakdown phenomenon occurs at this time. According to discriminant of condition, breakdown phenomenon occurs before pull-in effect occurs. Meanwhile, with the increase of applied voltage from 0V to 1600V and then, decreases to 0V, we observe the reversibility of DEA material and also discuss its hysteresis. In addition, the mechanical-electrical coupling model for DEAPs is also successfully investigated by electrostatic analysis and hyper-elastic stress analysis.