Bending Stresses in Box Beams as Influenced by Shear Deformation 380157
THE history of the box-beam problem is outlined. This problem has interested naval architects for a long time, but no design methods suitable for aeronautical applications have been evolved. The advent of stressed-skin construction in aeronautics has necessitated further development of the theory.
The problem of redistribution of bending stresses caused by shear deformation on the cover sheet, which cannot be avoided even in the most favorable cases, is considered as the most fundamental problem in box-beam design. Simplifying assumptions are discussed that permit a mathematical approach to the problem. Solutions for special cases finally are combined into a method of analysis intended chiefly for box-beam wings.
Analytical formulas are given for a simple case. With the help of these formulas, various structural arrangements of a small transport-size wing are compared. Numerical values are given for each case to show the error introduced by using the ordinary bending theory, and also to show how much extra weight is required to make up for the inefficiency caused by shear deformation.