Calculation for thin-walled closed contours of composite materials in torsion

We consider the torsion of closed torsion-box structures made of composite materials (such as airplane wings) under mechanical loads inducing only torsion of the construction without bending. The problem is solved by an energy method and using a conforming displacement method. The derived distribution law for the tangential stresses contains two terms and gives the Bredt formula for the special case of pure torsion. Since in solving the problem by a conforming displacement method the axial warping distribution law for torsion of a simple closed contour is obtained automatically, this method may be considered to be ecact in the sense of satisfying the continuity condition for the structural material.Deceased.Moscow State Aviation Institute (Technical University), Russia. Translated from Mekhanika Kompozitnykh Materialov, Vol. 33, No. 2, pp. 235–241, March–April, 1997.