Composite drilling is quite different from metals at the aspect of damages after machining. With the weak out-of-plane material properties amplified with drilling mechanism, the major failure characteristics is resulted as delamination which is mostly by excessive thrust force from drill bit. Previous studies resulted that permanent damages are mostly related to the critical thrust value [1]. However, from the current studies, maximum thrust loads can be controllable by controlling machining conditions as well as using high performance drill bits. This study further investigates thrust distribution along the drill cutting edge. For composite drilling, we believe that the distribution might greatly affect to the finial damage configuration. Imagine just after a drill tip penetrates composite plates, the left over fillet area have relatively small loads carrying capacity. We first analyzed thrust load distributions from the total thrust response, and then verified the relationship between distribution and measured thrust loads by using the developed finite element code. Finally, we discussed the damage caused by the machining conditions and load distributions.
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