PSI- Issue 9

Khadija Kimakh et al. / Procedia Structural Integrity 9 (2018) 243–249 Khadija. KIMAKH / StructuralIntegrity Procedia 00 (2018) 000–000

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Fig. 1. Fatigue specimen . After specimens preparation fatigue tests were performed with MTS 810 hydraulic testing machine shown in figure 2 with a maximum capacity 100 kN. The machined specimens were subjected to constant amplitude tension– tension axial fatigue. Tests were conducted in load control with a sinusoidal load waveform and for each batch of specimens four levels of stress load were applied. Table 4 listed the levels of stress. The fatigue tests were carried out with a constant frequency of 40 Hz and a stress ratio R = 0.1 (minimum load/maximum load) was applied throughout the experiment. Once the specimen was broken, the machine stopped automatically.

Fig. 2. Fatigue specimen configuration .

Table 4. Levels of the applied load.

levels

stress

σ max σ min

400 40

450

500 50

525 52.5

550 55

45

3. Result and discussion 3.1 S-N curve Figure 3 presents the S-N curve for the three batches of machined AISI 1045. Based on the experimental data and the observations of fatigue tests for every batch of specimens, the feed rate affects the fatigue life of the AISI1045 steel parts obtained by turning process. The results show that the machined specimens with a low feed rate f 3 = 0.05mm/rev have a longer lifetime than specimens machined with high feed rate (f 2 = 0.15mm/rev and f 1 = 0.25 mm/rev). We also notice that when thefeed rate decrease from f 1 = 0.25 mm/rev to f 2 = 0.15 mm/rev with a step of 0.1 mm/rev, the number of cycles to faillure increase with a percentage of 17% forσ max = 550MPa and 135% for σ max = 500MPa. But when it decrease from f 2 =