Peculiarities of calculation and design of smooth orthotropic panels with considering geometric nonlinear behavior

Abstract

When calculating the stability and bearing capacity of the panels of the caisson of the wing of an aerospace aircraft, it is necessary to take into account the presence of a heat-shielding coating, which also acts as an elastic base (EB) for the skin. The subject of this work is thin smooth orthotropic rectangular panels with an elastic base that does not perceive compressive and shear flows acting on the panel. The aim of the work is to develop methods for evaluating and designing composite panels associated with an elastic foundation, taking into account the possible geometrically nonlinear behavior under loads close to the design level. Note that the indicated level of loading can be realized only in full-scale static tests in the experimental justification of the strength of the wing structure. The paper presents analytical solutions of a geometrically nonlinear problem by the Bubnov-Galerkin method for rectangular orthotropic panels, taking into account the ER under the action of compressive and tangential forces. Based on the solutions obtained, methods for determining the thicknesses of orthotropic panels are proposed, taking into account two possible criteria: either reaching the ultimate strength stresses in a possible supercritical state, or reaching the limiting values of the deflection amplitude with geometrically nonlinear behavior. The last specified condition is a consequence of the requirements for the strength of the adhesive bond between the orthotropic skin and the heat-shielding layer. The paper considers smooth rectangular orthotropic panels with rigid support along the long sides and hinged support along the short sides.