Introduction

torsion twisting of a straight bar when it is loaded by moments that tend to produce rotation about the longitudinal axis of the bar (e.g. drive shafts, axles, propeller shafts, steering rods, drill bits)   shafts cylindrical members that transmit power through rotation (solid or tubular)   torques (twisting moments), T moments that produce twisting of a bar (units: ft-lb, N-m)