2. Loads transmitted by strong frames

Pressurization is the stress-dimensioning load case for the fuselage skin of a passenger aircraft. However, in certain phases of flight, the aircraft operates without pressurization (initial climb, final descent, dynamic landing).

These situations must be taken into account, not only because they represent significant introduced forces, but also because they give rise to a stability calculation. Indeed, while pressurization only induces tensile stresses (tension in the material), the loads discussed here involve compressive and shear stresses, for which local buckling between stiffeners must be taken into account, as it will be a factor of stiffener pitch (the skin thickness having been set by pressurization).

This section deals with these configurations in the symmetrical case. The treatment can easily be extended to asymmetrical cases...