同軸式壓電暨駐極體自感應致動器之研製

Abstract

本論文以駐極體複合材料與壓電材料應用為主軸，以同軸式結構對一種新型的自感應致動器做初步可行性的探討。本研究提出一種自感應致動器的結構，不同於以往的自感應致動器是利用後端電路處理運算的方式實現，本研究則是利用駐極體與壓電材料，使結構本身就會直接呈現出自感應致動之性質。本研究製程初步以浸塗法的方式在圓柱形狀之基材電極上，製作出不同材料之分層薄膜且為同軸式的結構，並對偏氟乙烯/三氟乙烯共聚物、環烯烴共聚物、聚苯乙烯等聚合物駐極體材料製成溶液，分別對不同材料為基材其浸塗拉伸速度、濃度之狀況作成膜厚度比較，初步實驗得知浸塗法膜厚控制之方法，以利於往後對材料極化時供應電壓之調整依據。本研究利用接觸式極化法成功使偏氟乙烯/三氟乙烯共聚物擁有良好的鐵電性質並驗證其壓電性質，其以作為結構裡感測功能；駐極體複合材料以環烯烴共聚物、聚苯乙烯等材料作複層疊加的方式儲存介面電荷，並在已形成之壓電層上疊加駐極體複合材料，利用電暈極化法完成極化程序，量測得到其表面電壓證明其材料的儲存電荷能力，其以作為結構致動之應用。整體結構初步已驗證有自感應的訊號，駐極體與壓電複合材料之聯合運用，並藉由同軸式多層形式可實現自感應的功能，未來可應用於預埋在撓性結構裡，作為自我結構健康感測、振動控制等等之相關應用。

This thesis focuses on the application of composite electret materials and piezoelectric materials as well as the practicability of a newly-developed coaxial-type self-sensing piezo-electret actuator. The structure of this newly developed self-sensing actuator potentially presented the possibility of creating a self-sensing actuator, is different from the conventional approach of self-sensing actuators as they are generally realized by post-processing the signal using subtraction circuit as that of the Wheatstone bridge circuit. The coaxial structure composed of several dip-coating layers in which the circular electrode is employed as the substrate. Several kinds of copolymers in the form of solutions were prepared, including P(VDF-TrFE), cyclic olefin copolymer and polystyrene. Moreover, based on the knowledge that the thickness of the film depends upon the material of the substrate, the rate of dip coating and the concentration of the solutions, the influences of these parameters are discussed. It is shown to be possible to control the film thickness from the preliminary experimental result, which is essential for voltage control in the poling process adopted. P(VDF-TrFE) copolymer with good ferroelectric properties has been successfully fabricated and its piezoelectric properties are also verified, which can serve as the sensor functions in the newly proposed self-sensing actuator. On the other hand, the actuating function is created by using the composite electrets made of cyclic olefin copolymer and polystyrene. The electret materials are formed in layers in order to store the interfacial charges. The composite electret layer was then coated on the piezoelectric film and the whole structure was poled by the corona charging method. The surface voltage was measured which indicates that the structure possesses charge storage capability. The self-sensing signals were successfully measured on the developed structure, which verified its practicability of serving as the self-sensing actuator. The applications of the self-sensing actuators, which constitute both electrets and piezoelectric materials in the coaxial and multi-layer form, include structure health monitoring, vibration control, etc.