Kunio Hayashi

Compressive Buckling of Rectangular Composite Plates with a Free-Edge Delamination

An experimental and analytical investigation is conducted on the compressive buckling behavior of orthotropic plates with a delamination. The plates, which have three simply supported edges and one free edge, are a simplified model of stiffener plates of a stiffened panel. A uniform width delamination is located at their free edges over the whole length. In the analysis, the Rayleigh-Ritz approximation method is adopted. A constrained point is introduced to allow the contact between the two delaminated surfaces. Imaginary springs about relative displacement and two relative slopes are introduced at the constrained point. With the constraint, buckling loads of physically admissible buckling modes can be obtained by ordinary buckling analysis. The global buckling load reduction is found to be significant and almost proportional to the delamination width. Local delamination buckling is found to occur when the delamination is located near the surface and its size is relatively large compared with that of the plate. The local buckling mode is different from the global one, and more wave number in loading direction and constrained points are necessary to obtain physically admissible solutions. The analytical results agree well with the experimental ones.

Effects of a free edge delamination on buckling of rectangular composite plates with two fixed loading and one simply-supported side edges

An experimental and analytical investigation is conducted on the compressive buckling behavior of an orthotropic plate with a free edge delamination. The plate is a simplified model of stiffener plates. In the present paper two loading edges are fixed and a side edge is simply-supported. The delamination locates at the free edge over the whole length. A Rayleigh-Ritz approximation method is adopted in the analysis. A constrained point is used to allow contacts between the two delaminated surfaces. At this point, relative displacement and two relative slopes are constrained through imaginary springs. The buckling load of the geometrically admissible buckling mode is obtained by an ordinary eigenvalue analysis. The analytical results are compared with the experiment and the results agree well. The effects of the width and the location of the delamination on the buckling behavior are studied analytically for the plates with various aspect ratios. Low local delamination buckling can occur at very low load whe...

Elastic buckling and flexural vibration of variable thickness annular plates under uniform in-plane forces along the inner and/or outer edges.

The problems of elastic buckling and flexural vibration of variable thickness annular plates have been analyzed by the Galerkin method. Natural vibration modes of the constant thickness annular plate without in-plane force have been adopted as admissible functions. Numerical calculations were executed for the annular plates of linearly varing thickness with uniform in-plane force along the inner and/or outer edges. Asymmetric deformations were also taken into consideration in this procedure. It has become clear that whether the taper ratio has influence on the buckling mode depends on the specific boundary conditions at the inner and outer edges. The proposed method could be easily extended to the cases where the thickness variations were more complicated.