Stresses in the single bayed three spar box beam are obtained from Eqs. (2.5), (2.6) and so on. By transforming them into Eqs. (2.25), (2.26), the higher approximation is given as expressed by Eqs. (2.32), (2.33) and reduced to Eqs. (2.35), (2.36). Hence the deviation stresses. from 0approximation are approximately proportional to γ. See Fig. 2 and Eq. (2.15).
Torsion center is expressed rigorously by Eq. (3.4), and approximated by Eq. (3.8). Hence, torsion center is positioned not at γ=0, but generally deviates backward by the effect of V, Higher approximation is given by Eq (3.11). See Fig. 3 and Eqs. (2.16), (2.17).
The method described above indicates the good guide line for treating the stresses in the sweptback three spars box beam.
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