Local Buckling Analysis of Composite Corrugated and Honeycomb Structures

Sachinthani Pathirana

This dissertation aims to investigate local buckling instability of composite corrugated and honeycomb core structures subjected to various loading conditions (e.g., axial compression, in-plane shear, and combined loading). Using classical shell theory, Rayleigh-Ritz method and a representative periodic element that encapsulates the repetitive buckling nature of the panel, semi-analytical solutions for the local buckling of composite corrugated sinusoidal panels, subjected to uniaxial compression, in-plane shear, and combined compression and in-plane shear, are developed. The generalized eigenvalue problems are established based on the first variation of the total potential energy and by modeling the buckling mode shapes with suitable displacement functions, which satisfy the periodic, simply-supported and rotationally-restrained boundary conditions. The curvilinear honeycomb core is discretized to individual corrugated elements; hence, the buckling solution of sinusoidally-corrugated elements serves as a lower bound one to the local buckling of sinusoidal honeycomb core walls. The buckling of prismatic honeycomb cores is also studied by modeling the flat core walls as discrete plate elements and developing an analytical expression for the rotational restraint stiffness at the intersection of core walls. Excellent correlations are observed between the present theoretical predictions and the numerical finite element analysis results. Parametric studies exploring the effects of the thickness, aspect ratio, corrugated amplitude, and material properties of the structure on buckling show that the developed solutions accurately capture the local buckling behavior at a greater extent of these parameters within the range of thin-walled shells. User-friendly equations to predict the critical local buckling of sinusoidal panels under axial compression and in-plane shear are obtained. The relationship of local buckling loads between compression and in-plane shear when applied simultaneously to a sinusoidally-corrugated structure is described through a fitted equation. The local buckling analysis of prismatic honeycomb core walls shows satisfactory comparison with the finite element results for the three honeycomb core geometries considered (i.e., hexagonal, rectangular and triangular). The recommended buckling solutions can be used in confidence to better comprehend the complex local buckling behaviors of these highly advantageous structures subjected to various loading as well as to improve and optimize design efficiency of corrugated and honeycomb composite structures.

Local Buckling Analysis of Composite Corrugated and Honeycomb Structures

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