線型形狀記憶合金之力學特性及其應用研究

A STUDY ON THE MECHANICAL PROPERTIES AND APPLICATIONS OF WIRE-TYPE SHAPE MEMORY ALLOY

賴躍仁(Yao-Jen Lai)

指導教授 ： 葉隆吉

大同大學/工程學院/機械工程學系所/博士(2011年)

摘要

本研究提出一種可應用於復健輔具的彎曲致動器，係採用多條線型的形狀記憶合金(Shape Memory Alloy, SMA Ti50Ni45Cu5)，利用SMA經加熱後，溫度上升時所產生之相變化進而引起記憶效應，此效應同時具有讓材料剛性由弱轉強並讓材料恢復其原狀的性質。本研究以不同的電流加熱SMA，在不同的操作溫度下，量測其彎曲變形量與荷重能力(相當於量測SMA所能提供的對外作用力)，將其結果導入樑的撓度公式，計算其等效的楊氏係數(E)。透過一系列的實驗結果與回歸分析後，得到多線式SMA驅動器輸出力的數學模型。
為充分掌握SMA於相變化過程中之剛性變化的特性，本研究中在SMA的操作溫度範圍內進行充分的實驗研究，以解明單線式的SMA在不同操作溫度下楊氏係數與操作溫度間的關係。於輔具設計應用時必須集合多根SMA線，以提供足夠的作用力，因此本研究更進一步探討多線式SMA組成的彎曲致動器之出力與其排列方式之間的關係。實驗結果由單根推展至多根並搭配不同的排列方式下，得到多線式SMA驅動器其彎曲驅動力與所配置的根數成線性關係。
最後，將此SMA彎曲致動器，應用於指關節與肢體關節復健輔具中，設計出『全指關節動態副木』；並製作了兩種型式：(一)固定型動態副木，適用於醫療診所使用，(二)攜帶型動態副木，適用於家庭復健使用，此種新型的復健輔具可提供指關節復健所需的作用力(約22N)。另一種『肢體關節型彎曲致動器』係採用TiNi基收縮式記憶合金，搭配齒輪組與多束SMA線的驅動機構可提供足夠的彎曲力量與角度。

關鍵字

形狀記憶合金 ； 復健輔具 ； 楊氏係數 ； SMA彎曲致動器

並列摘要

This study proposes a method by using a bundle of Shape Memory Alloy (SMA) wires to design a bending actuator for rehabilitation dynamic splints. The Shape Memory Effect is to heat up SMA for driving its phase transformation which changes and returns the material shape. The phase change is between Martensite (Mf) and Austensite (Af) induced by varying the alloy’s temperature. In the test, the electric current is applied to SMA, and the stiffness, loading and deformation are measured. The cantilever beam formula is used to estimate the equivalent Young’s modulus (E) with the measured results. After regression analysis for the series experimental results, the mathematical model of bundle-type SMA bending actuator output force is obtained.
In this study, all the necessary experimental investigations are carried out by operating temperature during Mf to Af (30~70°C) to explain the relationship between Young’s modulus and variant operation temperature of single SMA wire. In the applications of the dynamic splint, a bundle of SMA wires must be used to supply enough output force. Therefore, the relationship between the output force and the geometric arrangement of the bundle-type SMA bending actuator is further studied. The results reveal that the output force of bundle-type SMA bending actuator is linearly proportional to the number of wires.
Finally, the SMA bending actuator has been successfully applied to the rehabilitation dynamic splints of the finger joints and body joints. Two kinds of rehabilitation dynamic splints are developed: one is a fixed-type dynamic splint, which is used on medical treatment, and the other is a home use portable-type dynamic splint. This new type dynamic splint, can offer an output force of about 22 Netowns. Furthermore, a new type of rehabilitation dynamic splints of body joints is developed by combining a gear-train and a bundle of SMA wires to make a bending actuator to supply enough bending force and angle on body joints.

並列關鍵字

SMA ； SMA Bending Actuator ； Rehabilitation dynamic splints ； Young’s modulus

參考文獻

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