Elasticity/Torsion of thin walled closed sections

Torsion of thin-walled closed sections edit

The Prandtl stress function   can be approximated as a linear function between   and   on the two adjacent boundaries.

The local shear stress is, therefore,


where   is the parameterizing coordinate of the boundary curve of the cross-section and   is the local wall thickness.

The value of   can determined using


where   is the area enclosed by the mean line between the inner and outer boundary.

The torque is approximately