The document provides an overview of shaft lateral analysis. It discusses: 1) Performing shaft alignment calculations and positioning bearings to fulfill loading criteria. 2) Modeling the shaft system accounting for loads and thermal expansion. 3) Analyzing shaft deflection, stresses, and ensuring adequate lubrication film thickness. 4) Verifying bearing loads are within criteria and seals/components are compatible. 5) Describing bearing positioning using the reliable GAP/SAG method within tolerances.

1. Shaft Lateral Analysis overview

2. Name: Mohamed Zeid
Live in: Sweden
Age: 32
Role: Senior Rotordynamics Engineer.
Education:
B.Sc. In Naval Architecture & Marine engineering from faculty of engineering, Suez Canal University 2003.
B S I N l A hi &M i i i f f l f i i S C lU i i 2003
AMRINA , Associate Member at Royal Institution of Naval Architects.
Practical Experience:
[Jun to Sep, 2000], Suez Odense Marine Service (Training).
[Jun to Sep,2001:2003], Consulting Engineering Bureau (Training).
[Nov2003‐May2004], Ocean Classic International, (Structural analysis ).
[May 2004‐Jul 2005], TIMSAH Shipyard , (Hydrodynamics , Structural analysis,...)
[Jan 2006‐ ......], BERG PROPULSION, (Blade design, Shafting design and analysis / calculations,.....)
DNV Software User Conference
2
Rio ,Sep 2012

3. Propeller shaft alignment Background,
Analysis and Control.
Analysis and Control
Alignment background
Alignment background.
• Straight installation for all the bearings and the gearbox for installation
purposes only.
purposes only
Shaft analysis overview Sep2012‐MZ‐Rio 3

4. Alignment background.
• Straight installation for all the bearings and
position the gearbox flange to face the flange
of the propeller shaft.
of the propeller shaft
GB
SHAFT
Shaft analysis overview Sep2012‐ 4
MZ‐Rio

5. Alignment background.
Alignment calculations?
g
Shaft analysis overview Sep2012‐MZ‐Rio 5

6. Alignment background.
Shaft Analysis in Lateral
Shaft analysis overview Sep2012‐MZ‐Rio 6

7. Alignment background.
• Complete shaft analysis and positioning the shaft line bearings including the
gearbox / main engine to fulfill the allowable loading criteria for all shaft
component.
component
Shaft analysis overview Sep2012‐
7
MZ‐Rio

8. Alignment background.
Shaft analysis overview Sep2012‐MZ‐Rio 8

9. Determine optimum domain.
Operating Condition Straight ahead analysis Vessel loading condition
Shaft analysis overview Sep2012‐MZ‐Rio 9

10. Propeller shaft Analysis and Control.
Reposition and adjusting Modeling the shaft system
Analysis
the bearing
NOT Ok Shaft line deflection and
bending stresses.
g
Ok
NOT Ok
Bearing loads
Ok
NOT Ok
NOT Ok Other shaft component
p
(Seals, breaks, couplings,…..)
Ok
Describe how the bearing
positioned (GAP/SAG).
Verifying the alignment.
(Jack load)
Reporting.
R i
Shaft analysis overview Sep2012‐MZ‐Rio 10

11. Modeling the shaft system.
• The tool used for build the model is NAUTICUS MACHINERY, SHAFT
The tool used for build the model is NAUTICUS MACHINERY, SHAFT
ALIGNMENT which developed by DNV.
• The shaft system modeled by the geometric of the shaft components.
• The model also is including the propeller load, gear tooth
forces, stuffiness and thermal expansion effect.
Vertical : Horizontal :
• All the above is modeled for different operating
p g
conditions as:
‐Propeller static & Gearbox cold.
‐Propeller static & Gearbox warm. Fa
Ft
‐Propeller running at full pitch & Gearbox cold.
Fr Fbt
‐Propeller running at full pitch & Gearbox warm
Propeller running at full pitch & Gearbox warm. r
‐Propeller running at 0‐pitch & Gearbox warm.
Shaft analysis overview Sep2012‐MZ‐Rio 11

12. Shaft line deflection and bending stresses.
• Checking the shaft deflection through all conditions and look if there is any
excessive deflection specially near by the bearing location.
Shaft analysis overview Sep2012‐MZ‐Rio 12

13. Shaft line deflection and bending stresses.
• Checking the bending stresses through all conditions and look into the bending
stresses specially in the way of the propeller and in between the bearings.
M
σz-max
Shaft analysis overview Sep2012‐MZ‐Rio 13

14. High slope of the shaft inside the aft stern
tube bearing
bearing.
• Checking the shaft deflection inside the aft stern tube bearing and ensure
Checking the shaft deflection inside the aft stern tube bearing and ensure
that there is enough lubricating film between the shaft and the bearing.
Lubricant White metal
Bearing pressure
Shaft analysis overview Sep2012‐MZ‐Rio 14

15. High slope of the shaft inside the aft stern
tube bearing
bearing.
• What s happening in this case?!
What’s happening in this case?!
The oil film thickness is decreased
by increasing the relative slope
ness [mm]
0.4
0.3
03 0
l film thickn
0.1
0.2 0.2 Slope of shaft,
0.3
03 [mm/m]
Minimum oil
0,1
0
M
1 1.5 2
Bearing length / shaft diameter
Shaft analysis overview Sep2012‐MZ‐Rio 15

16. High slope of the shaft inside the aft stern
tube bearing
bearing.
• Solution !
Bearing pressure
Shaft analysis overview Sep2012‐MZ‐Rio 16

17. High slope of the shaft inside the aft stern
tube bearing
bearing.
• Examples !
p
Bearing damaged due to high slope Bearing material yielded under the
of the shaft inside the bearing. high bearing pressure due to high
slope and the bearing still working.
slope and the bearing still working
Shaft analysis overview Sep2012‐MZ‐Rio 17

18. Bearing loads criteria.
• Slide surface bearing minimum load !
g
The bearing have to be loaded with a minimum load which
avoiding the bearing wiping / burning.
Shaft analysis overview Sep2012‐MZ‐Rio 18

19. Bearing loads criteria.
• Slide surface bearing max load !
g
The bearing have to be loaded below the maximum load
which avoid to over load the bearing.
‐Projected pressure in aftmost bearing should not exceed
8 bar (Oil lub.).
‐Projected pressure in other journal bearings should not
exceed 12 bar in the lower speed range and 18 bar in the
upper speed range (Oil lub.).
• Ensure the direction of the resultant force is far
from the lubricant feeding grooves !
from the lubricant feeding grooves !
Shaft analysis overview Sep2012‐MZ‐Rio 19

20. Bearing loads criteria.
• Roller bearing minimum load !
g
The bearing have to be loaded with a
minimum load which avoiding the bearing
slipping and hammering effect.
Shaft analysis overview Sep2012‐MZ‐Rio 20

21. Bearing loads criteria.
• Roller bearing maximum load !
g
The bearing have not to be loaded more than the maximum load which
allowed by the bearing manufacture to achieve the required life time.
Shaft analysis overview Sep2012‐MZ‐Rio 21

22. Other shaft component (Seals, breaks,
couplings…)
couplings )
• Seals
‐ In case of one stern tube bearing installations, the deflection of the shaft at the
location of fwd seal is of interest.
g p y g
‐ In case of the aft stern tube bearing was slope bored by taking off material from the
aft end of the bearing, The aft seal adjustment tolerance have to be checked.
• Breaks
‐ The brake type and compatibility with the shafting system should be checked .
yp p y g y
At Rest Start‐up During Operation
• Couplings and other components
‐ The couplings and all other integrated devices compatibility with the shafting system
should be checked and related criteria from the device manufacture have to be fulfilled.
Shaft analysis overview Sep2012‐MZ‐Rio 22

23. Describe how the bearing positioned.
GAP/SAG
• GAP‐SAG method
The GAP/SAG method have been found that the most reliable way to
The GAP/SAG method have been found that the most reliable way to
describe how the bearings positioned related to each other.
y1
SAG
A B
A
B
B
A SAG
GAP
y3
Shaft analysis overview Sep2012‐MZ‐Rio 23

24. Describe how the bearing positioned.
GAP/SAG
• GAP‐SAG method
The GAP/SAG method have been found that the most reliable way to
The GAP/SAG method have been found that the most reliable way to
describe how the bearings positioned related to each other.
SAG x
A 1
B
A
B
B
A SAG
GAP
x
3
Shaft analysis overview Sep2012‐MZ‐Rio 24

25. GAP/SAG
SAG installation! Seen from aft
top
t
y1 x1 B
sag
p
p.s. x2 x4 s.b
B sag
A
x3 A
bottom
Rotating forward shaft (B) with dial gauge
Vertical sag (A below B) = (x3-x1)/2
B
A Horizontal sag (A to s.b. from B) = (x4-x2)/2
sag
Rotating aft shaft (A) with dial gauge
y3 Vertical sag (B below A) = (x3-x1)/2
Horizontal sag (B to s.b. from A) = (x4-x2)/2
Shaft analysis overview Sep2012‐MZ‐Rio 25

26. GAP/SAG
GAP installation!
top
Seen from aft: y1
A
B s.b y2 y4 p.s.
y3
bottom
Rotating forward shaft (B) with dial gauge
gap Vertical gap (at bottom) = y3-y1
Horizontal gap (at s.b. side) = y4-y2
Rotating aft shaft (A) with dial gauge
Vertical gap (B below A) = y3-y1
Horizontal gap (B to s.b. from A) = y4-y2
Shaft analysis overview Sep2012‐MZ‐Rio 26

27. GAP/SAG
• Why the GAP/SAG is a reliable method?
The reason of GAP/SAG reliability is that this method is a describe how the shaft line
The reason of GAP/SAG reliability is that this method is a describe how the shaft line
parts relate to each other and then compensating the bearing position to keep the shaft
line as it wanted to come over the change on the hull deflection which changed after
g
launching .
Shaft analysis overview Sep2012‐MZ‐Rio 27

28. GAP/SAG
• GAP/SAG Tolerance
Any alignment calculation have to provide a minimum tolerance of +/ 0.05 mm for both
Any alignment calculation have to provide a minimum tolerance of +/‐ 0.05 mm for both
GAP and SAG figures.
Why?!
‐ Manufacturing quality.
‐ Tool accuracy in use.
‐ Practical experience.
Important note: The GAP and SAG
tolerance they are influencing each other!
Shaft analysis overview Sep2012‐MZ‐Rio 28

29. GAP/SAG
• GAP/SAG measuring tools
Dial gauge. Laser equipment.
Shaft analysis overview Sep2012‐MZ‐Rio 29

30. Verify that the alignment have been done
correctly.
correctly
After aligning the shaft with the GAP‐SAG method, the alignment
have to be checked that it is done correctly.
Jack load method.
X [mm]
F1 F2 F3 F4
Fj
F [kN]
F3 = F j ⋅ Corr
Fj F3
Shaft analysis overview Sep2012‐MZ‐Rio 30

31. Jack load test.
actual jacking curve
actual jacking curve 1
including hysteresis
from friction
X [mm]
theoretical 2
jacking curve
jacking curve 3
3
1 2
F [kN]
Fj
Shaft analysis overview Sep2012‐MZ‐Rio 31

32. Alignment verfication
Load cell
Shaft analysis overview Sep2012‐MZ‐Rio 32

33. Alignment verfication
Jack load notes!
The jack load results can very a lot due to:
Jacking Bearing
‐ Shaft manufacturing quality.
60
‐ Tools accuracy.
y 50
‐ Practical experience.
Jack load [kN]
40
30
20
10
0
0 90 180 270
Degrees
Shaft analysis overview Sep2012‐MZ‐Rio 33

34. Jack load tips!
Checking that the dial gauge not influenced by the jack stiffness and foundation:
x x
F F
Shaft analysis overview Sep2012‐MZ‐Rio 34

35. Jack load tips!
400
Fwd stern bearing Int. bearing
Jack correction factor: Cj=1.0154
Knuckle point factor: Cj=0.9727
K kl i f C 0 9727
Shaft analysis overview Sep2012‐MZ‐Rio 35

36. Jack load tips!
1300
Fwd stern bearing
Int. bearing
Jack correction factor: Cj=1.0370
Knuckle point factor: Cj=0.8917
Shaft analysis overview Sep2012‐MZ‐Rio 36

37. Jack load tips!
Bearing with no load, Too much friction loss Stick-slip, oil suction,
or jacking to short. pump pulses
Check slope !
0.001
Initial contact Several bearings Jacking until contact
ntil
in top of bearing unloaded in top of bearing
Shaft analysis overview Sep2012‐MZ‐Rio 37

38. Alignment verfication
• Strain gauge method
Commutat
- More complicated measurements Pick-Up
or
transformer
- Require bending moment in the shaft
- Costly
- Often much time needed to analyse
- Few companies are able to carry out the analysis
+ Accurate
+ Analytical solution possible for some shafting systems Antenna, Wire around shaft
+ Hot running condition can be verified
+ Data stored online Strain gauge
PC etc.
Shaft analysis overview Sep2012‐MZ‐Rio 38

39. Reporting
• The classification societies have a standard requirements in case of the alignment report is
required.
Alignment report structure:
p y
‐ Complete shaft analysis.
‐ Alignment method (GAP‐SAG).
‐ Alignment verification (Jack load).
‐ Ali
Alignment procedures.
t d
Shaft analysis overview Sep2012‐MZ‐Rio 39

40. Questions ?
Questions and discussion !
BERG PROPULSION PRODUCTION AB
Mohamed Zeid
Naval Architect - R t d
N l A hit t Rotordynamics S
i Specialist
i li t
Direct: +46 31 30 10 736
Mobile: +46 761 175 022
E-mail: mohamed.zeid@bergpropulsion.com
Box 1005
475 22 Öckerö
Sweden
Office: +46 31 976 500
www.bergpropulsion.com
Shaft analysis overview Sep2012‐MZ‐Rio 40