PSI - Issue 4

Ivo Černý / Procedia Structural Integrity 4 (2017) 35– 41 Author name / Structural Integrity Procedia 00 (2017) 000 – 000

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the axle at the distance of 1715 mm from the hub edge, in the lateral direction, using a special auxiliary static hydraulic cylinder. During static loading, values in both tension and compression sides were monitored. Dynamic rotating bending load during fatigue test was controlled by means of SGs located at the distance 250 mm from the hub, as recommended. However, in addition, dynamic values of all SGs were independently monitored by a HBM Spider 8 device. Note that the load frequency was considerably high, approximately 30 Hz.

3. Results and discussion

Results of the static experimental stress analysis are in Figs. 5 and 6, where compressive stresses are plotted as absolute values. For the conversion of measured strain values to stresses, E-modulus 206 GPa, evaluated separately by standard static tensile tests of small specimens, was considered. Concerning the SG chain near the hub, some strain redistribution due to the vicinity of the press fit, shown in Fig.  6 was expected. Note that particularly at the compression side, the values very close to the vicinity of the hub edge, at the distance 5 mm, are significantly higher, by 16 % in comparison with the theoretical nominal value. The range of affected stresses is significant, more than 60 mm from the hub edge, i.e. more than one quarter of the axle diameter.

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Experimental - tension side Experimental - compression side Experimental - average

Experimental - tension side Experimental - compression side Experimental - average

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Theoretical stress at distance 30 mm = 78.42 MPa Average actual stress at distance 0 - 60 mm = 77.96 MPa

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Theoretical stress - load 55.72 kN at distance 1715 mm from hub edge: y = -0.0465x + 79.8145

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Stress (MPa)

Stress (MPa)

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Theoretical stress - load 55.72 kN at distance 1715 mm from hub edge: y = -0.0465x + 79.8145

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0 100 200 300 400 500 600 700 800 Distance from hub edge (mm) Fig. 5. Actual stresses as a dependence on distance from hub edge during static loading

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Fig. 6. Detailed stress redistribution near the hub edge during static loading

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Theoretical stress Experimental - tension side Experimental - compression side Experimental - average Experimental - dynamic average Experimental dynamic - regression line

Theoretical stress Experimental - tension side Experimental - compression side Experimental - average Experimental - dynamic average

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Actual dynamic average stress near the hub by 10.7 % higher than actual static average stress

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y = -0.0465x + 79.8145

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y = -0.0556x + 81.6133

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0 100 200 300 400 500 600 700 800 Distance from hub edge (mm) Fig. 7. Comparison of static stresses and dynamic stresses during fatigue test

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Distance from hub edge (mm)

Fig. 8. Detailed comparison of average dynamic stress amplitude with the static one near the hub

As regards the area outside the zone affected by the hub, there was an excellent agreement between theoretical and experimental stresses at the distances 250 mm, 500 mm and 750 mm. Note that the calibrating static force at the point 1715 mm from the hub was 55.72 kN. This does not concern, however, dynamic stresses.