• Journal of Korean Society of Steel Construction
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• v.22 no.3
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• pp.219-228
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• 2010

This paper describes an experimental research on the structural behavior and the ultimate strength of longitudinally stiffened plates subjected to local, distortional, or mixed-mode buckling under compression. The stiffened plate undergoes local, distortional, or interactive local-distortional buckling according to the flexural rigidity of the plate's longitudinal stiffeners and the width-thickness ratios of the sub-panels of the stiffened plate. A significant post-buckling strength in the local and distortional modes affects the ultimate strength of the longitudinally stiffened plate. Compression tests were conducted on stiffened plates that were fabricated from 4mm-thick SM400 steel plates with a nominal yield stress of 235MPa. A simple strength formula for the Direct Strength Method based on the test results was proposed. This paper proves that the Direct Strength Method can properly predict the ultimate strength of stiffened plates when the local buckling and distortional buckling occur simultaneously or nearly simultaneously.

• Composites Research
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• v.19 no.6
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• pp.23-31
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• 2006

We measured mechanical properties, including Young's modulus, effective bending modulus and nominal fracture strength of nanohoneycomb structures using an Atomic Force Microscope(AFM) and a Nano-Universal Testing Machine(UTM). Anodic aluminum oxide(AAO) films are well suited as nanohoneycomb structures because of the simple fabrication process, high aspect ratio, self-ordered hexagonal pore structure, and simple control of pore dimensions. Bending tests were carried out for cantilever structures by pressing AFM tips, and the results were compared with three-point bending tests and tensile tests using a Nano-UTM. One side of the AAO films is clogged by harrier layers, and looks like a face material of conventional sandwich structures. Analysis of this layer showed that it did not influence the bending rigidity, and was just a crack tip. The present results can act as a design guideline in applications of nanohoneycomb structures.