Please use this identifier to cite or link to this item: http://hdl.handle.net/11455/1566
標題: 氣動工具元件破壞之有限元素分析研究
Finite Element Studies for Ruptures Occurred in Air-Powered Tools
作者: 李兆榮
關鍵字: air-powered tools;氣動工具槍;plate-buckling;buckling mode;critical load;平板挫曲;挫曲模態;臨界負載
出版社: 機械工程學系
摘要: 
滑板和滑動檔門因其本身高速移動與衝擊行為而導致的破壞乃是氣動工具槍常見與重要的問題。所以在本研究中,將分別針對此兩元件做適當的結構分析。
考慮兩個因素:(1)軸向壓力通常較少使金屬發生材料破壞;(2)滑板沿著水平方向的衝擊是不穩定的行為而且會一直發生上下波動的動作。所以,小側向位移將引起滑板的破裂。因此滑板的分析變得複雜且困難。本文中將以下列程序來處理:
首先,因滑板有著平坦的外型和高長度厚度比,此處將提出一特別設計的平板有限元素。此二次元素可幫助吾人更易瞭解應力應變行為,且元素上的每個節點都包含了三個獨立變數:一個位移和兩個旋角。其次,用上述元素來模擬滑板的自然振動模態而得到了前七個最低的模態。最後,對得到的振動模態進行挫曲行為的分析,以求得相對於每一挫曲模態的臨界負載。由挫曲模態和臨界負載,吾人可以了解和預測滑板的破壞。
在滑動檔門的結構分析方面,分別對傳統型與四個改良型的滑動檔門進行研究。每一種型態模式間的應力分佈可以提供為未來設計與應用上的參考。分析結果與真實滑動檔門破壞情形互相比較可將發現本研究的正確性,因此非常值得對滑動檔門進行更深入的研究。

Failures of slide-plate and shutter caused by their high-speed motion and impact behaviors are common/important problems occurred in the air-powered tools. So, in this study, proper structural analyzing procedures with respect to these two components are performed.
Considering two factors: (1) axial compression is generally less to give metals the opportunity of material failures, and (2) The impact motion of slide-plate along the horizontal is not steady and an up-side-down motion is frequently occurred. Therefore, the small lateral motions in slide-plate cause its rupture. The analysis of slide-plate thus becomes complicate. It is preceded as follows.
Firstly, it is known that the geometry of slide-plates is flat with high length/thickness ratio; so, a specifically designed flat-plate finite element is introduced here. This element is quadratic and each node contains with three independent variable, one displacement and two slopes, may give better understanding of the stress-strain behaviors than others. Secondly, the above element is used to simulate the natural modes of the slide-plate and seven lowest modal shapes are obtained. Finally, the derived modal shapes are implemented into the buckling behaviors of the slide-plate and critical load with respect to each buckling mode is thus obtained. From the buckling modes and critical loads, the failure of the slide-plate can thus be understood and predicted.
In the structural analysis of the slide shuttle, one traditional type and four improved types are studied here. The stress distribution in the model for each type gives the contrast for future applications. Results comparing with the fracture shapes from the actual shuttles are quite significant. Further studies on the slide shuttle are highly recommended.
URI: http://hdl.handle.net/11455/1566
Appears in Collections:機械工程學系所

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