玻璃纖維蜂窩巢複合材料具低密度(0.192 g/cm3)與三軸向非等性之剛性模數(0.19–1.79 GPa)，因此，廣泛用於航太和汽車產業之耐撞擊(crashworthiness)設計。於常態負載時，蜂窩巢結構之W-T與L-T平面可以乘載荷重；當衝擊產生時，蜂窩巢結構之L-W平面可提供減震和吸收能量之機能。雖然如此，玻璃纖維蜂窩巢複合材料之六角結構設計與幾何之不連續性(discontinuity)，造成切削之振動，加工後尺寸精度變動、加工面之纖維扯出(pulled out)與蜂巢巢壁撕裂(tearing)。本研究建立之切削力學模型，可以預測切削力之變化。並配合實驗工作，以鑽石鍍層之分割螺旋刃與交叉複斜刃繞切刀具，操作切削速度(100–300 m/min)與進給率(0.2–1.0 mm/rev)，進行驗證。實驗結果顯示，刀具之進給率與刀具幾何為影響切削力與切削溫度之顯著因子。其物理機制為，當巢壁厚與刀具直徑比值(R_{t/D})最大時，產生波動峰值(spiky wave)切削力。而高切削速使得剪力角(\emptyset_n)提高，產生絕熱剪切(adiabatic shearing)，造成切削力與切削溫度之下降。當操作高切削速度配合高進給率，可降低切削力並增加剪應變率，進而降低材料之表面粗糙度。當以統計方法過濾、辨識並移除實驗數據之離群點，可擬合切削力模型，並得模型精度~88.17%。再經由多指標最佳化模型可建議同時得到切削力、切削熱與表面粗糙度之適切結果。加工表面之形貌與顯微組織，裂縫成長機制與切削條件之關聯皆已討論。

The glass fiber honeycomb composite is characterized with low density (0.192 g/cm3) and a wide range of elastic modulus (0.19–1.79 GPa) due to the hexagonal structure in the cell. Under a normal load, the W-T and L-T planes can steadily be absorbed and redistributed by the load. When impact occurs, the L-W plane provides advantages of shock absorption and energy dissipation, making this material widely used in the crashworthiness design of the aerospace and automotive industries. Nonetheless, the hexagonal structure design and geometric discontinuity of the glass fiber honeycomb composite can hinder the machining process due to the unbalanced cutting forces in each transient. Hence, vibration-induced variations in cutting force, poor dimensional accuracy and degradation of the machined surface integrity are resulted. The mechanics established in this study can predict the cutting force in orthogonal, oblique and dual-oblique cutting actions. In conjunction with the experimental work, the nicked helical-flute router and the cross-flute router coupling with the cutting speed (100–300 m/min) and feed rate (0.2–1.0 mm/rev) are used to examined the effects on the cutting forces, cutting temperature and machined surface integrity as well as the fracture mechanisms in the fibres. Experimental results show that the feed rate and tool geometry are significant factors affecting cutting force and cutting temperature. When the ratio of wall thickness to tool diameter (R_{t/D}) is maximised, it produces a spikey wave and whereby increasing the cutting forces. The high cutting speed increases the shear angle (\emptyset_n) and generates adiabatic shearing, which resulting in a decrease in cutting force and cutting temperature. The high feed rate combined with the high cutting speed reduces the cutting force and increases the shear strain rate, thereby reducing the surface roughness of the material. When statistical methods of data filtering and processing, identification and removal of outliers from experimental data are conducted. In the fitting of the analytical models, the accuracy of the cutting forces can be obtained (R2~88.17%). In the multi-objective optimization, the preferable parameter sets simultaneously obtain the optimums of cutting forces, cutting temperature and surface roughness. The morphology and microstructure of the machined surface, the relationship between the cutting conditions and crack propagations are all presented and discussed.

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