Ric rit: >Jim...and others may correct me where I am wrong here.... but I THINK >that Ron was getting at the more general question of what shape of a >shank yields the most stiffness for same << diameters >> >I dont really see the point in using inertia in this regard myself... I >fail to see the connection between a things moment of inertia, and its >stiffness... Besides there are formulas to do show stiffness for >different shapes rather directly unless I'm mistaken. Yes. Ron's measure of stiffness of an elastic beam is the flexural rigidity EI where E is Young's modulus and I is the moment of inertia of the beam about the neutral axis (through the centroid of the cross section). That's where the moment of inertia comes into it - and those values are tabulated for beams of various cross sections, e.g. standard steel structural beam of various cross-sectional shapes. A loaded elastic beam will take on a curvature according to its flexural rigidity. Hard to describe this stuff without sounding obscene methinks.... Stephen -- Dr Stephen Birkett Associate Professor Department of Systems Design Engineering University of Waterloo Waterloo, Ontario Canada N2L 3G1 Davis Building Room 2617 tel: 519-888-4567 Ext. 3792 PianoTech Lab Ext. 7115 mailto: sbirkett[at]real.uwaterloo.ca http://real.uwaterloo.ca/~sbirkett
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