- Consider a 2024-T4 aluminum material with ultimate tensile strength of 70 ksi. In a given application, a component of this material is to experience ‘released tension’ stress cycling between minimum and maximum stress level of 0 and σmax ksi. As an engineer, you want to have 99.9% chance that the component does not fail before 1,000,000 cycles. What should be the value of σmax?