A solid circular shaft is subjected to a bending moment $$M$$ and torque $$T$$ simultaneously. Neglecting the effects of stress concentration, the equivalent bending moment is expressed as

A pair of spur gears with $${20^ \circ }$$ full-depth involute teeth is used to transmit $$3.5$$ $$kW$$ of power. The pinion rotates at $$700$$ $$rpm$$ and has pitch circle diameter of $$100$$ $$mm.$$ Assuming a single pair of teeth in contact, the total force acting on a gear tooth (in $$kN$$) is

In a machining operation with turning tool, the tool life $$(T)$$ is related to cutting speed $$v$$ $$(m/s),$$ feed $$f(mm)$$ and depth of cut $$d(mm)$$ as $$$T = C\,v{\,^{ - 2.5}}\,{f^{ - 0.9}}\,{d^{ - 0.15}}$$$
where, $$C$$ is a constant. The suggested values for the cutting parameters are: $$V=1.5$$ $$m/s,$$ $$f=0.25$$ $$mm$$ and $$d=3$$ $$mm$$ for normal rough turning. If the operation is performed at twice the cutting speed and the other parameters remain unchanged, the corresponding percentage change in tool life is ______________.

The Merchant circle diagram showing various forces associated with a cutting process using a wedge shaped tool is given in the Figure

The coefficient of friction can be estimated from the ratio