sin αst

FURLING AND YAW ANALYSIS
The bearing material is bronze alloy with a characteristic limited contact pressure of 50
MPa, see att. 14. The values of the partial safety factors are established in accordance with
IEC 61400-2 under the assumption of so called full characterisation of the material proper-
ties [5, p. 89]. This implies that factors such as environmental effects and manufacturing
methods have been taken into consideration when determining the material properties. �m
is set to 1.1 and �f to 3.0. This results in the following yield limit state:
plim
The contact area Ab in the bearing is calculated on basis of the bearing diameter Db = 93.0
mm and the bearing height Lb = 10.0 mm.
(I.30)
(I.31)
The 13.9 kN tower load of load case G is assumed to be applied directly at the centre of the
upper bearing in the yaw system. This yields a maximum contact pressure of:
It is concluded that the limit state for the material is not exceeded.
�
fk
� m� f
� 15.2MPa
Ab LbDb 930 mm 2
� �
Pmax
�
RB
Ab
� 14.6MPa
pmax �
plim
(I.32)
(I.33)
211