PSI - Issue 10

D.G. Ntritsos et al. / Procedia Structural Integrity 10 (2018) 288–294

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D.G. Ntritsos et al. / Structural Integrity Procedia 00 (2018) 000 – 000

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FE analysis results that two stress concentration regions appear, one (region A) on the edge of keyway at about the endpoint of the edge’s straight part and region B, on the step fillet as shown in Fig.3(a,b). A full loading cycle was simulated and the values of Von Mises-, 1 st Principal- and Z-normal-stresses were monitored on both stress con centration areas.

4. Results

4.1. Experimental results

The test ran for five different applied loads. At all the single notched specimens fractured started from the notch, as it was expected but at all the double notched specimens the fracture started from region A (see Fig.3a) although the region B was under greater loading. Typical fractured surfaces are shown on Figs.4(a,b).

(a)

(b)

Fig. 4. Stereoscopic pictures of double notched specimen fracture surfaces. The experimental results are summarized in the diagram shown in Fig.5, where the number of specimen life cycles plotted versus applied load of the fatigue machine.

350

Single Notched Double Notched

300

Single Notched Trendline Double Notched Trendline

250

Load [N]

200

150

100

3.00E+04

3.00E+05

3.00E+06

Number of Cycles

Fig. 5. Comparative F-N Diagram, Single Notched versus Double Notched Specimen.