**2.2 Bending fatigue machine**

In bending fatigue tests with the aim of initiation of cracks from the notch created in the 2025 aluminum specimen, we need a bending fatigue machine. The fatigue machine designed to test aluminum alloy 2025 specimens are mounted on a lathe and receives the moment and force applied to the specimen for fatigue from the machine's engine. The rotational motion created by the motor is converted to linear motion through the crankshaft connected to the drill chuck of the device and the connecting rod. This linear motion is then transmitted to one side of the specimen by a bar. The other side of the sample is fixed with a clamp so that we can see the movement on only one side [7]. **Figure 4** shows the bending fatigue machine. The bending fatigue test is performed in the case of fixed grip loading with a rate of 12 mm per cycle.

**Figure 3.**

*Schematic and dimension of aluminum alloy 2025 specimen.*

**Figure 4.** *Schematic and component of bending fatigue machine.*
