Aluminum wrought alloys like EN AW-6082 or EN AW-7075 are often used for suspension parts such as uprights or wishbones for lightweight construction of the higher priced automotive segment. Heat sources like the braking or exhaust system lead to higher service temperatures of the suspension components nearby, which can affect its strength properties. Due to loads in operation and prolonged service life, components are designed by fatigue strength.
The present thesis includes tension compression fatigue tests of EN AW-6082-T6 and EN AW-7075-T73 at temperatures of 85 °C and 115 °C. Furthermore, a comparison of results with artificially aged samples is done. The aging cycle is modeled on the thermal load over the components service life. For testing quality of the fatigue tests, statistical analysis of the impact of sample quality on testing results is carried out.
In comparison to room temperature, a reduction in fatigue life at 5.000.000 cycles of 7 % at 85 °C and 12 % at 115 °C was determined for EN AW-6082-T6 alloy. With EN AW-7075-T73, a drop in fatigue life of 22 % was measured between 85 °C and 115 °C. No difference in fatigue life was experienced between performing the modeled aging cycle beforehand or not. Likewise, no correlation was found among sample quality and fatigue cycles before cracking, but with quality and result scatter.