MT-1620 al.2002 Figure 12 10 Representation of forces on thin closed cross-section under torsion tl ds Force:dF=τtds k contribution to torque dt= httds (h= moment arm) Note: h, t, t vary with s (around section) Total torque dT=∮τthds Paul A Lagace @2001 Unit 12-14MIT - 16.20 Fall, 2002 Figure 12.10 Representation of forces on thin closed cross-section under torsion Force: dF = τ t ds contribution to torque: dT = hτ t ds (h = moment arm) Note: h, τ, t vary with s (around section) Total torque = ∫ dT = ∫ τ t hds Paul A. Lagace © 2001 Unit 12 - 14