PSI - Issue 8

A. Terrin et al. / Procedia Structural Integrity 8 (2018) 276–287

283

A. Terrin et al./ Structural Integrity Procedia 00 (2017) 000 – 000

8

1

1

12

1

12

2

12

1

2

1

12

12

2

13

SAP

EAP

HPSTC

PP

LPSTC

Figure 10. Sequence of meshing between sun and planet gear.

The signal of the three gauges are shown in Figure 11 for a complete revolution of the planet relatively to the carrier. Considering the strain gauges in the joint and carrier sides, the strain pattern measured during the meshing with planet gear 1 is considerably different with respect to the one observed during the meshing with planet gears 2 and 3.

400 Strain [µ ε ] 800 1200

400 Strain [µ ε ] 800 1200

400 Strain [µ ε ] 800 1200

x

x

x

T s = 520 Nm n w = 30 rpm

x [mm]

x [mm]

x [mm]

0

0

0

0 10 20 30

0 10 20 30

0 10 20 30

1000 Strain [ με ] 1500

Joint side Central Carrier side

500

0

0

50

100

150

200

250

300

350

γ R [ ]

-500

-1000

-1500

Contact with planet 3

Contact with planet 2

Contact with planet 1

Figure 11. Strain patterns at three different position along the face width. The upper charts report the values of strain relevant to the contact with the three planet gears, when the contact occurs at the HPSTC of the sun gear.

The strain measured by the three gauges in correspondence of the contacts with the three planets at the HPSTC of the sun gear are reported in Table 2. Strain values relevant to contacts with the three planet gears, in correspondence of the HPSTC of the gauged tooth. Such location is considered as reference because it is easily recognizable in the chart and is relatively far from the pitch line, where the change in the direction of friction forces causes a perturbation in the strain pattern. It can be noted that the values measured by the strain gauge in the central position are quite repeatable, with a difference among the values measured in correspondence of the contact with the three planet gears lower than 8%. However, the two lateral gauges measure very different strain values during the contact with the first planet as opposed to those registered in the contact with the second and third planet gears. It could be verified that this behavior is repeatable in the subsequent revolutions.

Table 2. Strain values relevant to contacts with the three planet gears, in correspondence of the HPSTC of the gauged tooth.

Contact with planet gear 1

Contact with planet gear 2

Contact with planet gear 3

1048 1004

518 967 528

461 927 537

Joint side

Central

113

STRAIN [µε]

Carrier side