IHS ESDU Method of calculating stress distribution in a reinforced symmetrical shell under bending. STRUCT 00.06.01

ESDU Struct 00.06.01 gives a graphical iterative method for determining the stress distribution corresponding to a bending moment, or the bending moment corresponding to a maximum strain for a reinforced symmetrical shell. The method is based on the assumption that plane sections remain plane after bending and requires a load-deflection curve to be calculated for each typical panel, comprising one plate in combination with one stringer. A first guess is made for the position of the neutral axis of the shell. Then a strain-distance graph is readily constructed, where distance is measured along the axis of symmetry of the shell cross section, because the strain will vary linearly on that axis and is known to be zero at the neutral axis. From the graph the panel loads may now be calculated and summed. If they are not in equilibrium further iterations with modified positions for the neutral axis are required until equilibrium of the direct loads is achieved.