not-yet-known not-yet-known not-yet-known unknown In this work, the effect of aging variables of a proposed heat treatment and their combined impact on the fatigue life of an Al6061-T6 were evaluated. Al 6061-T6 specimens were prepared according to the ASTM E466 and then heat-treated, followed by fatigue tests in a rotating beam testing machine. The results showed an increase in the fatigue life of Al6061-T6 up to 4.47 times and up to 4.69 regarding the aging temperature and the aging time, respectively. Three empirical models to estimate the fatigue life in function of the aging time, aging temperature, and both aging time and temperature were obtained by fitting the experimental, showing a correlation of R 2 =90%, R 2 =79.2%, and R 2 =80.1%, respectively. The proposed heat treatment also decreased the energy consumed by the process by 67.8% than that consumed by the T6 heat treatment of the raw material as a consequence of reducing the time of the process.

Three fatigue damage models based on entropy, originally developed for constant amplitude loading, were assessed and compared each other in order to state whether its applicability can be extended towards variable amplitude loading conditions. A variable amplitude loading history, applied on a 2024-T3 aluminum alloy reported in the literature, was processed using both rainflow cycle counting and spectral techniques to transform it into a distribution of simple processes with constant amplitudes, then the damage models were assessed under the new loading conditions. The results showed that the model by Khonsari, combined with the rainflow technique, exhibited the highest accuracy with respect to the referenced experimental results with -0.67 standard deviation from the average data and 16% error from the median. Therefore, it is possible to assess the fatigue damage accumulation in metallic materials under variable amplitude loading through a thermodynamic approach with models developed for constant amplitude loading.