Low-frequency sinusoids for enhanced shear buckling performance of thin plates

Thin plates subject to shear are ubiquitous in structures, used in webs of flexural members, shear walls, curved aircraft fuselages, ship hulls, etc. Given shear buckling concerns, these slender elements must be designed to balance plate depth and thickness. As slenderness limits capacity, strategies such as stiffeners or corrugations can enhance efficiency but are not without costs. In plate girder fabrication, the use of transverse and/or longitudinal stiffeners introduce poor fatigue details, while corrugation requires web forming and complex flange-to-web welding. The authors propose an alternative strategy, forming low-frequency sinusoidal (LFS) patterns along the plate's longitudinal axis as a novel, less fabrication-intensive approach to enhancing shear capacity of thin plates. The frequencies studied here are much lower than those used in commercial corrugated products and previous research, resulting in lower forming stresses, prospective fabrication using conventional semi-automatic welding techniques, and potentially improved fatigue behavior. Experimentally validated finite element models are used to evaluate sinusoidal frequency, amplitude, initial geometric imperfection, plate depth, and plate slenderness. Elastic shear buckling load, ultimate shear load, and shear yielding are used to evaluate effects of the parameters. Significant increases in shear strength and material efficiency can be achieved using an LFS approach. A standardized low-curvature LFS shape with 1.2 m wavelength is applicable to a wide range of plate depths and thicknesses without the need for specialized equipment to form the plate or weld the web-to-flange interface. LFS plates combine durability, material efficiency and ease of fabrication in a strategy that can benefit the industry.