中文摘要：

以直刃尖刀超声辅助切割Nomex蜂窝芯的简化模型为基础,建立基于脆性断裂力学理论的超声辅助切削动态力模型,并分情况讨论了刀具与材料间的相对运动关系。分析指出在不同振幅条件下,材料的切割破坏存在断续和连续两种形式,进而推导了切割过程中的切削力的理论公式。其中超声振幅、刀具前倾角、进给速度和超声频率等参数对材料切削力大小均有影响。在理论分析的基础上,开展了超声辅助切割Nomex蜂窝芯复合材料实验。试验结果表明,进给方向的超声振幅和刀具前倾角对切削力的影响较大：当进给方向的超声振幅从0到15μm变化、刀具前倾角从15°到45°变化时,切削力均可降低70%~80%;进给速度和超声频率对于切削力影响较小：当进给速度从500到6000 mm/min变化12倍时,切削力仅变为1.5倍;超声频率35 k Hz与15 k Hz相比,切削力降低10%~30%。试验结果与理论分析结论一致。

英文摘要：

Based on the simplified model of ultrasonic-assisted cutting for Nomex honeycomb core with straight knife, the dynamic force model for ultrasonic-assisted cutting is established based on brittle fracture theory. The relative motion relationships between the tool and the composites material are discussed in several cases. Analysis indicates that under different conditions there are two failure forms in breaking of the material, namely intermittent and continuous failure forms. Then the theoretical formula of the cutting force in cutting process is derived. The parameters of ultrasonic amplitude, forward angle of tools, feed rate and ultrasonic frequency are found to be of obvious influence on cutting force during the material cutting process. On the basis of theoretical analysis, the experiments of ultrasonic-assisted cutting Nomex honeycomb core are carried out. The results show that the ultrasonic amplitude in the feed direction and forward angle of tool have a great influence on the cutting force： As the ultrasonic amplitude in feed direction changes from 0 to 15~tm, the forward angle of the tool changes from 15 ~ to 45 ~,the cutting force reduced by 70 %- 80%; Meantime, feed rate and ultrasonic frequency have less influence on cutting force： As the feed rate changes from 500 mm/min to 6000 mrrffmin with a multiplication of 12 times, there is only a multiplication of 1.5 times with the cutting force. Compared with the case of 15 kHz, the cutting force reduced by 10% to 30% when the frequency is 35 kHz. The experimental results are in agreement with the theoretical analysis.