Study the effect of notches on bending fatigue strength of 2024 aluminum sheets

In the present study, the effect of holes on the curvature fatigue strength of 2024 aluminum sheets. Has been studied by taking a model of this type and cutting it into models with the dimensions required for testing and by using a central hole as the main variable by making a central whole (CH) with a diameter of (1mm). The device used in this research is a Reversed bending machine of type HI-TECH from a British origin, all tests were done at a constant stress ratio (R = -1), a rotational speed of 6000 rpm and a frequency (100 Hz). The study was practically and theoretically (using the ANSYS15.0 program). The results showed that stress is affected by the presence of holes and we notice increased stress in the samples that contain holes more than the core samples that do not contain holes and thus we notice that fatigue strength decreases in the samples that contain a central hole by (32%) of the core samples by the practical side on the theoretical side, strength of fatigue less than percentage (43.7%). The yield strength was found by tensile test equal to (73.6 MPa) and the ultimate tensile strength (195.2 MPa) as for the hardness value (59.7). Also, from the results obtained, it appears that streaking acts as stress centers, thereby increasing stress and thereby reducing the number of cycles and consequently failure.