複合材料由於許多優異的特性已被廣泛應用於各個領域中，尤其是許多高規格的產品更是常常會使用到複合材料，疊層狀的複合材料是ㄧ種常見的複合材料結構之一，結構由多層的預浸材疊層堆疊而成，這種結構的優點是材料特性可以透過改變疊層方式來做改變，具有較大的彈性，缺點則是加工的時候容易產生脫層現象而導致加工品質受到影響。
平板與圓管結構的複合材料在鑽孔時，由於幾何形狀不同，導致鑽孔所造成的脫層嚴重程度也不相同，脫層的嚴重程度一般來說主要與軸向推力大小有關，找出結構開始脫層的軸向推力值，也就是臨界軸向推力，就能夠預測結構在怎樣的鑽削條件下會產生脫層。因此在本研究中利用有限單元模擬的方式，藉由破裂分析分別找出平板結構與圓管結構的臨界軸向推力，發現圓管的臨界軸向推力略小於平板。得到模擬值後，利用實驗的方式將模擬值與實際值進行比較，以驗證模擬結果的正確性及實用性，最後發現模擬值與實驗結果相當接近，證明以有限單元模擬的方式來預測臨界軸向推力是確實可行的。

Owing to remarkable properties, composite materials are generally used in varieties of industries especially for high value products. Laminated composites are commonly used which are composed of several prepreg plies. This kind of structure has an advantage of tailoring material properties easily by changing the way of lamination. But the trade-off is that delamination tends to occur between plies.
There is a difference on degree of drilling-induced delamination between planar structure and tubular structure. In general, the magnitude of thrust force is the most determining factor on drilling-induced delamination. If one can obtain the critical thrust force beyond which fracture occurs, it is possible to predict the onset of delamination. In view of this, a finite element simulation is conducted to determine the value of critical thrust force for each structure. It is found that the critical thrust force of tubular structure is slightly lower than that of planar structure. After that, experiments are made to examine the accuracy and applicability of the simulations .The values obtained from simulation and experiment are very close. As a result, it is verified that critical thrust force determined by simulation is feasible.

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