Analytical Review of Account Methods and Experimental Approaches to Stress-Strain State Investigation of Structurally-Anisotropic Aircraft Panels Made from Composite Materials

Abstract

The different approaches were analyzed to investigate the stress-strain state problems of structurally-anisotropic panels made from composite materials. The classification of mathematical models, analytical methods of calculations, numerical methods of calculations, testing results are presented in this review. New mathematical model relations for the stress-strain state investigation of structurally-anisotropic panels made of composite materials are presented. The primary scientific novelty is the further development of the theory of thin-walled elastic ribs related to the contact problem for the skin and the rib with an improved rib model. A promising area of research is the design of composite aircraft structures in the field of production technologies. We consider the residual thermal stresses and the preliminary tension of the reinforcing fibers with respect to the panel production technology. The stress-strain state problem results in the boundary value problem when solving for the eighth order partial derivative equation in the rectangular field. A computer program package is developed in MATLAB. The computer program package has been utilized for multi-criteria optimization of the design of structurally-anisotropic aircraft composite panels. The results of testing series are presented as the verification of the proposed mathematical model.

Stress–Strain Behaviour of Reparable Composite Panel with Step-Variable Thickness

“…Summing up, we can draw a conclusion about the reliability of the mathematical model for calculating the stress-strain behaviour of the composite shell of step-variable thickness. Better convergence of theoretical results with the values obtained using multilayer three-dimensional finite elements confirm the need to use the refined theories in studies of structures of the considered type [28,29].…”

“…One of the aspects of these problems is the development of more reliable methods for determining the stress-strain behaviour near the area of distortion of the stress state, i.e., the area near the patch attachment and stepped variation of thickness of the structure being repaired [28]. This is explained by the fact that for these cases the classical theory does not give satisfactory agreement with practice because of the three-dimensional nature of the stress-strain behaviour [29,30]. The paper [31] offers a modified approach to analytical modelling of the effect of the patch attachment area on the stress-strain behaviour of a weakened composite panel.…”