shaft lateral analysis overview

Shaft Lateral Analysis overview

Name: Mohamed Zeid

Live in: Sweden

Age: 32

Role: Senior Rotordynamics Engineer.

Education:

B S I N l A hi & M i i i f f l f i i S C l U i i 2003B.Sc. In Naval Architecture & Marine engineering from faculty of engineering, Suez Canal University 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,.....)

2DNV Software User Conference

Rio ,Sep 2012

Propeller shaft alignment Background,Analysis and ControlAnalysis and Control.

Alignment backgroundAlignment background.

• Straight installation for all the bearings and the gearbox for installation

purposes onlypurposes only.

3Shaft analysis overview Sep2012‐MZ‐Rio

Alignment background.

• Straight installation for all the bearings and

position the gearbox flange to face the flange

of the propeller shaftof the propeller shaft.

GB

SHAFT

Shaft analysis overview Sep2012‐MZ‐Rio

4


Alignment calculations?g

Shaft analysis overview Sep2012‐MZ‐Rio 5


Shaft Analysis in Lateral



• Complete shaft analysis and positioning the shaft line bearings including the

gearbox / main engine to fulfill the allowable loading criteria for all shaft

componentcomponent.


Determine optimum domain.

Straight ahead analysisOperating Condition Vessel loading condition


Propeller shaft Analysis and Control.

Modeling the shaft system

Shaft line deflection and bending stresses.

AnalysisReposition and adjusting

the bearingNOT Ok

gOk

Bearing loads

Other shaft componentOk

NOT Ok

NOT Ok p(Seals, breaks, couplings,…..)

Ok

Describe how the bearingpositioned (GAP/SAG).

NOT Ok

positioned (GAP/SAG).

Verifying the alignment. (Jack load)

R i


Reporting.

Modeling the shaft system.

• The tool used for build the model is NAUTICUS MACHINERY, SHAFTThe 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.

• All the above is modeled for different operating Vertical : Horizontal :

p g

conditions as:

‐Propeller static & Gearbox cold.

‐Propeller static & Gearbox warm.

‐Propeller running at full pitch & Gearbox cold.

‐Propeller running at full pitch & Gearbox warm

Ft

Fa

Fr Fbt


Propeller running at full pitch & Gearbox warm.

‐Propeller running at 0‐pitch & Gearbox warm.

r


• Checking the shaft deflection through all conditions and look if there is any

excessive deflection specially near by the bearing location.



• 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


High slope of the shaft inside the aft sterntube bearingtube bearing.

• Checking the shaft deflection inside the aft stern tube bearing and ensureChecking the shaft deflection inside the aft stern tube bearing and ensure

that there is enough lubricating film between the shaft and the bearing.

White metalLubricant White metalLubricant

Bearing pressure



• What’s happening in this case?!What s happening in this case?!

The oil film thickness is decreased by increasing the relative slope

0 3ness [m

m]

0.4

0

0.2

0.3

l film

thickn

Slope of shaft,[mm/m]

0.20.1

0 3

0Minim

um oil

0,1[mm/m]0.3


21.50 1M

Bearing length / shaft diameter


• Solution !

Bearing pressure



• Examples !p

Bearing material yielded under the high bearing pressure due to high slope and the bearing still working

Bearing damaged due to high slope of the shaft inside the bearing.


slope and the bearing still working.

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.



• 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 !


• Roller bearing minimum load !g

The bearing have to be loaded with a

minimum load which avoiding the bearing

slipping and hammering effect.



• 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.


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.

‐ In case of the aft stern tube bearing was slope bored by taking off material from the g p y g

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.

Describe how the bearing positioned.GAP/SAGGAP/SAG

• GAP‐SAG methodThe GAP/SAG method have been found that the most reliable way toThe GAP/SAG method have been found that the most reliable way to

describe how the bearings positioned related to each other.

SAGy1

SAG

A BAB

A BSAGA B

y3GAP


Describe how the bearing positioned.GAP/SAGGAP/SAG

• GAP‐SAG methodThe GAP/SAG method have been found that the most reliable way toThe GAP/SAG method have been found that the most reliable way to

describe how the bearings positioned related to each other.

SAG xSAG

A B1A

B

A BSAGA B

x3

GAP

24Shaft analysis overview Sep2012‐MZ‐Rio

GAP/SAG

SAG installation!t

Seen from aft

sag

B

y1 Bx1

x4x2 s.bp.s.

top

AB sag

Ax3

42p

B

3

bottom

Vertical sag (A below B) = (x3-x1)/2Rotating forward shaft (B) with dial gauge

sagA

B

y3

Horizontal sag (A to s.b. from B) = (x4-x2)/2

Vertical sag (B below A) = (x3-x1)/2Rotating aft shaft (A) with dial gauge


Horizontal sag (B to s.b. from A) = (x4-x2)/2

GAP/SAG

GAP installation!

AB

y1

topSeen from aft:

B

y3

y4y2s.b p.s.

bottom

gap Vertical gap (at bottom) = y3-y1

Rotating forward shaft (B) with dial gauge

bottom

Horizontal gap (at s.b. side) = y4-y2

Vertical gap (B below A) = y3-y1

Rotating aft shaft (A) with dial gauge


Horizontal gap (B to s.b. from A) = y4-y2

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 lineThe 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

launching .g


GAP/SAG

• GAP/SAG ToleranceAny alignment calculation have to provide a minimum tolerance of +/‐ 0.05 mm for bothAny 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!


GAP/SAG

• GAP/SAG measuring tools

Dial gauge. Laser equipment.


Verify that the alignment have been donecorrectlycorrectly.

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

F [kN]

F

Fj

CorrFF j ⋅=3

F


Fj F3

Jack load test.

actual jacking curve 1actual jacking curveincluding hysteresisfrom friction

1

X [mm]

theoretical jacking curve

23jacking curve 3

F [kN]1 23


Fj

Alignment verfication

Load cell



Jack load notes!

The jack load results can very a lot due to:

‐ Shaft manufacturing quality.60

Jacking Bearing

‐ Tools accuracy.

20

30

40

50

Jack

load

[kN

]

y

‐ Practical experience.

0

10

0 90 180 270

Degrees


Jack load tips!

Checking that the dial gauge not influenced by the jack stiffness and foundation:

x x

F F


Jack load tips!

400

Int. bearingFwd stern bearing

Jack correction factor: Cj=1.0154

K kl i f C 0 9727


Knuckle point factor: Cj=0.9727

Jack load tips!

1300

Int. bearingFwd stern bearing

Jack correction factor: Cj=1.0370

Knuckle point factor: Cj=0.8917


j

Jack load tips!

Bearing with no load, or jacking to short.Check slope !

Too much friction loss Stick-slip, oil suction,pump pulses

Jacking ntil contact

0.001

Initial contact Several bearings


Jacking until contact in top of bearing

Initial contact in top of bearing

Several bearingsunloaded


• Strain gauge method

- More complicated measurements- Require bending moment in the shaft- Costly

Commutatortransformer

Pick-Up

- Often much time needed to analyse- Few companies are able to carry out the analysis

+ Accurate+ Analytical solution possible for some shafting systems+ Hot running condition can be verified+ Data stored online

Antenna, Wire around shaft

Strain gauge


PC etc.

Reporting

• The classification societies have a standard requirements in case of the alignment report is

required.

Alignment report structure:

‐ Complete shaft analysis.p y

‐ Alignment method (GAP‐SAG).

‐ Alignment verification (Jack load).

Ali t d‐ Alignment procedures.


Questions ?

Questions and discussion !

Mohamed ZeidN l A hit t R t d i S i li t

BERG PROPULSION PRODUCTION AB

Naval Architect - Rotordynamics Specialist

Direct: +46 31 30 10 736Mobile: +46 761 175 022E-mail: [email protected]

Box 1005 Box 1005 475 22 ÖckeröSweden Office: +46 31 976 500

www.bergpropulsion.com


shaft lateral analysis overview

Technology