Pre-buckling and Buckling Analysis of Variable-Stiffness, Curvilinearly Stiffened Panels

Abstract

This work illustrates a fast numerical approach for analyzing the pre-buckling and buckling response of innovative panel configurations for aerospace structures. Specifically, the approach allows composite panels with variable-stiffness skins and stiffened by curvilinear stringers to be studied in a fast yet accurate manner. The method of Ritz is applied in conjunction with first-order theories for modeling the skin and the stiffeners, the former described referring to Mindlin plate theory, the latter to Timoshenko beam model. Due to the excellent convergence properties of the approach, pre-buckling stress distributions can be captured with reduced effort. Similarly, accurate buckling predictions can be obtained with relatively few degrees of freedom, much less with respect to typical models relying upon the use of finite elements. Results are presented for a number of test-cases from the literature, illustrating the potential of the proposed approach as a mean for performing preliminary studies with reduced computational effort.

Fast analysis of curvilinearly stiffened panels operating in the postbuckling field

“…The panel configuration C2 is considered here, extending the test case presented in a previous work by one of the authors for the linearized buckling analysis, see Ref. [57],…”

“…Meshfree strategies for curvilinearly stiffened panels were proposed in the past years for isotropic and straight-fiber composite configurations, see Refs. [51][52][53][54][55], and recently to incorporate variable stiffness skins [56,57].…”

Buckling Optimization of Variable Stiffness Composite Panels for Curvilinear Fibers and Grid Stiffeners

“…It was shown that curvilinear stiffeners could result in a better design than straight stiffeners, but not for all load cases and boundary conditions. Other authors [7,23] parametrized the stiffener geometry using Bézier curves. For NURBS and Bézier curves, special attention was required to ensure that the stiffener lied within the panel boundary.…”

Skin-Stringer Assembly Using Radial Basis Functions for Curvilinearly Stiffened Panels

“…When modeling the stiffeners as beam elements, the glue contact may influence the accuracy of the analysis results because it is very sensitive to the offset between the stiffener's centroid and the plate's median plane [10]. Additionally, both semi-analytical and mesh-less methods were developed for buckling and vibration analysis of curvilinearly stiffened plates by Tamijani and Kapania [11][12][13], Vescovini et al [14,15] and Alanbay et al [16]. For practical aircraft panels, which have both complex geometry and complex boundary conditions, it is not efficient to use these semi-analytical methods as one needs to find admissible trial functions to satisfy those complex essential boundary conditions.…”