proppastie
Well-Known Member
I was recently made aware of possible problems using Grape FEA. The T recovery and J inertia must be calculated for non circular sections and input manually. As has been always mentioned here using automated methods without an understanding of the basic principals can get you in trouble. From Grape instructions manual below.
J Inertia |
The polar moment of inertia as specified in the geometry property. For a circular section, J is the polar moment of inertia given by the formula ( P i x R^4 ) / 2. Radius R is the T Recovery distance For a non circular section, GBW32 calculates the torsional shear stress using the formula SHEAR STRESS = ( Torque x radius ) / J and thus J is the torsional resistance of the non circular section referred to as K in several references such as Roark & Young ( see also Bibliography, Gieck, K and Gieck, R.). For a non circular section T-Recovery must be calculated.
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