Cold test nodal and distorsion analysis

1. 1
TORSIONAL DISTORSION ANALYSIS
1806 RPOA COLD TEST-NEW SOLID TIP
| STUDY
Ra’uf Tailony
05/10/2017
ORIGINAL DESIGN
Figure 1: New Driveline tip.
NODAL ANALYSIS
Figure 2: Vibration nodes locations on driveline.
Mode 2,3Mode 4,5

2. 2
Figure 3: Torque and speed signatures (ramping 0-2000 rpm).
MODELING ASSUMPTIONS
Homogeneous material along the driveline (AISI 4130 steel Annealed at 860 0
C).
All parts are rotating at the same speed (relative angular velocity=0).
Electrical motor slipping is neglected.
Residual friction is neglected.
All considered bearings are ball bearing type with zero lateral forces.
Center of gravity is assumed to be static on a dynamic assembly.
Geometry is treated as a fixed-free structure.
Rayleigh’s equations solution is exact with no iteration.
Ramping up speed = 1500 rpm Ramping down speed = 1500 rpm
- 1500 rpm is a critical speed.
- Critical Frequency = 230 - 280
Hz.
- Critical Modes are 1, 2 and/or
3.
- Critical Excitation order is 12th
order (Engine and E-motor 12th
orders are coinciding).
OBSERVATIONS

3. 3
INITIAL CONDITIONS
Input torque = 300 N.m.
Rotational speed range = 0 - 2000 rpm.
Centrifugal force is proportional to the driveline’s speed.
Excitation diagram is dependent on a standard V8 engine specifications.
FREQUENCY ANALYSIS RESULTS
Figure 4: Mode shape vs. Frequency with and without E-motor bearing.

4. 4
INTERFERENCE DIAGRAMS AND CRITICAL SPEEDS
Figure 5: Campbell diagram for mode1 (bearing considered) and mode3 (bearing ignored).
NARROWING ROOT CAUSE PROBLEM
Figure 6: Original driveline components nodal effects.
Mode 1 effect
Mode 2,3 effect

5. 5
Mode “E-motor bearing
ignored”
Freq. [Hz]
“E-motor bearing
considered”
Freq. [Hz]
1 104 2301
2 120 600
3 280 615
4 815 1050
5 816 1080
Table 1: Frequencies vs. modes.
1
Highlighted frequencies are found in the torque signatures.