Easing cracks with the method of tensile triangles

Abstract

The "Method of Tensile Triangles" was introduced as a design tool that mimics the rules of nature for the shape optimization of a design scheme with respect to increased fatigue life and reduced weight. It was inspired by the shape of buttress roots in trees. Like them it bridges a corner-like notch with tensile loaded triangles. The notch shape may be scaled up and down according to the individual design space limitations of the technical structure. Failure often starts at the cracks tips and slot ends in technical components, because these domains are highly loaded due to stress concentrations. Conventional rounding or drilling away of these crack tips can only lower the stresses. By means of the "Method of Tensile Triangles" , stress concentrations can be minimized and the endings redesigned and compressed. In this paper the "Method of Tensile Triangles" will be explained and it will be shown, by results of Finite Element analyses, how the destructive effect of crack tips and slot ends in technical components can be eliminated. © 2010 WIT Press.