Introduction to Aircraft Structural Analysis (Elsevier Aerospace Engineering)

512 CHAPTER 17 Torsion of Beams

Fig.17.8

Twisting of a rectangular section beam.

Fig.17.9

Displacements due to twist and shear strain.

andγacorrespondtotheshearstresssystemproducedbyapositiveanticlockwisetorque.Clearly,the
totalaxialdisplacementofthepoint1inthewebandcovermustbethesamesothat

−

b

2

aθ

L

+γb

b

2

=

a

2

bθ

L

−γa

a

2

fromwhich

θ=

L

2 ab

(γaa+γbb)