Determination of Minimised Kt Values and Boundary Shapes for a Class of Quasi-Rectangular Holes in Infinite Plates
DEFENCE SCIENCE AND TECHNOLOGY GROUP FISHERMANS BEND (AUSTRALIA)
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Transferable solutions for stress-minimised quasi-rectangular holes in a two-dimensional infinite plate have been determined for a number of remote loading conditions and a wide range of hole aspect ratios. These include uniaxial, equibiaxial and reversed biaxial loading cases. The analytical shape and tangential stress equations for these quasi-rectangular holes can readily be used to obtain solutions for other specific biaxial loading cases that are of interest. The equation for the radius of curvature for these shapes has also been derived. Tables and plots of shape parameters and stress concentration factors are provided, enabling the stress-minimised quasi-rectangular hole shapes to be easily and rapidly applied by designers. These shapes produce peak stresses that are often within 10 of those obtained by free-form shape optimisation, and they can serve as initial shapes for subsequent free-form shape optimisation analyses. The source code for the program that was used to determine the stress-minimised quasi-rectangular hole shapes as a function of hole aspect ratio is provided, as is a set of functions that are suitable for use in spreadsheets. For the first time, these tools provide an automated procedure that enables a designer to set up a biaxial loading condition of interest and then determine sets of stress-minimised quasi-rectangular hole shapes that vary as a function of hole aspect ratio.