A material will fail when a certain point is subjected to unfavorable conditions. Breakage occurs when the “load” exerted on that point reaches a particular level. The state of stress that brings about the collapse of the material is known as “stress state limit” and is de—ned by a group of three main stresses, σ1, σ2, and σ3, and by direction cosines that identify either the planes in which they operate or are from the six stress components σx, σy, σz, τxy, τyz, and τzx. It is well recognized in machine component design that it is indispensible to know about the danger of breakage of any given component. De—ning such a parameter is therefore very useful for indicating the degree of safety of the structure being designed.