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Bone loss due to thermo necrosis may weaken the purchase of surgically placed screws and pins, causing them to loosen postoperatively. The heat generated during the bone drilling is proportional to cutting speed and force and may be partially dissipated by the blood and tissue fluids, and somehow carried away by the chips formed. Increasing cutting speed will reduce cutting force and machining time. Therefore, it is of interest to study the effects of the increasing cutting speed on bone drilling characteristics. In this article, the effects of the increasing cutting speed ranging from 500 up to 18,000 r/min on the thrust force and the temperature rise are studied for bovine femur bone. The results of this study reveal that the high-speed drilling of 6000-7000 r/min may effectively reduce the two parameters of maximum cortical temperature and duration of exposure at temperatures above the allowable levels, which in turn reduce the probability of thermal necrosis in the drill site. This is due to the reduction of the cutting force and the increase in the chip disposal speed. However, more increases in the drill bit rotational speed result in an increase in the amount of temperature elevation, not because of sensible change in drilling force but a considerable increase in friction among the chips, drill bit and the hole walls.

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A smart stretchable material is developed from a composite of carbon nanotube (CNT) and fluoroelastomer (FKM), which is fabricated via an internal melt‐mixer method. A unique, double‐percolated, electrically conductive network is observed with ultralow percolation thresholds of 0.45 phr and 1.40 phr CNT. This provides the CNT/FKM nanocomposites with a wide range of strain sensitivity. Thin‐film nanocomposites at the first plateau of conductivity show an ultrahigh sensitivity with a gauge factor (GF) of 1010 at 23% strain for 0.6 phr and of 6750 at 34% strain for 1 phr. At the second plateau of conductivity, 1.5 phr nanocomposite corresponds to higher levels of strain of 78% strain with ultrahigh GF of more than 4 × 104 and 2 phr nanocomposite to almost 100% strain with GF of 1.3 × 105. The CNT/FKM nanocomposites possess a high elongation at break of 430% and up to 232% strain sensitivity. The unique distribution of CNTs in the polar fluoroelastomer FKM facilitates simultaneous high sensitivity and high stretchability, and improved mechanical strength over reported polymer‐based nanocomposite stretchable sensors. The novel, stretchable CNT‐based FKM conductors have great potential for wearable electronics such as stretchable sensors, stretchable light‐emitting diodes (LEDs), and human motion monitoring.

No abstract