- 學位論文
含裂縫光碟片之動態特性與破裂行為之研究
Dynamic and Fracture Behavior of Rotating Cracked Disk
摘要
現今市售光碟機中，最快倍數為DVD-ROM 16倍，隨廠牌不同其轉速約為10000rpm。然而，在各大科技公司追求更高容量及更快讀取速度的考量，作者探討具有不同裂縫長度時之光碟片在12000rpm旋轉速度下，動態特性與後續之破裂行為。研究的方法是將針對一般的光碟片以有限元素分析法分析光碟片在均質不同厚度、不同裂縫長度與不同旋轉速度下等參數下自然頻率之變化，以及各個模態振型之比較。而當碟片本身具有裂縫，其碟片之裂縫尖端會有應力集中的現象產生而易於破裂，其應力相對的比沒有裂縫之碟片來的高。因此，本研究亦使用有限元素分析軟體分析具有不同裂縫長度之光碟片其轉速與應力強度因子之關係，並且以實驗方式驗證。在此個案研究中，發現光碟片之自然頻率與碟片厚度與旋轉速度成正比，而與裂縫長度成反比。同時光碟片上之裂縫長度會隨著轉速增加而造成磁片之破壞。
並列摘要
In the recent market of CD-ROM drive, the fastest speed is DVD-ROM 16X which is about 10000rpm. One of the techniques to increase the data access rate is to increase the rotating speed of disk. However, high revolutions of disk will yield high stresses and cause vibration of disk due to high centrifugal force and unbalance effect of system. Therefore, the purpose of this study is to investigate the dynamic and fracture behavior of rotating cracked disk. The Finite Element Method is used to analyze the nature frequencies and mode shape of disk subjected to different geometric and loading condition like thickness, crack length, and rotating speed. The method is also used to study the stresses and stress intensity factor of crack tip of disk for a given crack length. The results of this case study show that the natural frequency is direct proportional to the thickness and revolution of disk, and is inverse proportional to the crack length .In addition, the existence of a crack will increase the change of fracture of disk especially for the disk crack high rotating speed.