benchmark of bolted bearing connection models in wind turbines

1
benchmark of bolted bearing connection models
in wind turbines
Marcel van Duijvendijk Alfred Kalverboer Theo de
Gruiter

• Athens, 1 March 2006

2
bolted bearing connection
connection

• pitch bearing
• yaw bearing
• design driver
• expensive
• phenomena
• 4 models
• bolt strength
• reliable economic

3
physical bearing phenomena
phenomena

• boundary conditions
• bending load
• stiffness distribution
• blade interaction
• contact angle
• varies with load
• varies along circumference
• ovalisation
• pre-stress
• bearings and bolts
• deformations
• contact loss between components

4
spring section model
spring section

• Germanischer Lloyd
• boundary conditions
• axial load
• cyclic symmetry
• contact angle
• balls as pressure-only springs
• fixed contact angle
• pre-stress
• bolts
• constant component contact
• along circumference

Germanischer Lloyd Department WE
5
2.5D harmonic axi-symm. model
2.5D

• Mecal FEM model and spreadsheet
• boundary conditions
• bending Load
• Non-axi-symmetric stiffness
• contact angle
• balls as axial springs, radial forces
• harmonic loading 0Ø, 1Ø and 2Ø
• spreadsheet for bearing behaviour up to 2Ø
• load dependent
• realistic ovalisation
• pre-stress
• bolts
• constant contact along circumference

6
contact section model
contact section

• boundary conditions
• axial load
• cyclic symmetry
• contact angle
• balls as solids
• ball-raceway contact
• load dependent
• pre-stress
• bolts and bearing
• constant component contact along circum.

7
contact angle
Upper raceway
Lower raceway
low load
High load
8
180
180

• Mecal extension of contact section
• boundary conditions
• axial, bending and shear loads
• half symmetry assumed
• contact angle
• load dependent
• realistic ovalisation
• pre-stress
• bolts and bearing
• realistic component contact
• along circumference

9
model comparison
comparison
10
relative axial bearing displacements
displacements
11
relative radial bearing displacements
displacements
12
bolt stress
bolt stress
13
design strength reserve and costs
design
14
conclusion recommendations

• bearing connection
• important
• reliable
• cost efficient
• 4 models
• different phenomena
• different results
• 2.5D is best on conservative side
• 180 model seems most promising
• further model development and validation required