sin αst

Assumption Description
Medium term load-duration
class M
BLADE ATTACHMENT
States a load-duration from 1 week to 6 months of the
total life time a [53, p. 45]
Service class 3 The service class is used for components that are fully
exposed to wetting [53, p. 44]
High safety class Is used as failure may cause personal injury or consider-
able social consequences [53, p. 43]
Bolt quality 4.6 Implying a bolt yield strength of 240 MPa and an ulti-
mate strength of 400 MPa [31, p. 63]
a) Load case E occurs at a wind speed of 14 m/s. Using the probability function of appendix A.1, it may be
calculated that the load-duration over a period of 19 years, which is the estimated longevity of the
wind turbine, is 59 days.
Table F.2: Description of the assumptions used in the calculations
From the above correction factor kmod is set to 0.722 [53, p. 40]. The partial coefficient �m is
set to 1.80 [53, p. 48] and �f is set to 1.5 [53, p. 47]. This is equal to a summarised safety
factor of 3.7.
Fk of (F.1) is calculated from the combined load capacity of one bolt connection and one
press-in connector. This is multiplied by the number of bolts in the joint connection, under
the assumption that the load capacity is equal for all components in the connection [31, p.
92].
Where the variables are:
Fk � �Fpi � Fb�nb
� 21.4kN
Description Symbol Value
Rated load capacity for press-in connector Fpi 4.1 kN
Rated load capacity for bolt connection Fb 3.03 kN
Number of bolts in the connection nb 3
Table F.3: Load capacity for press-in connectors and bolts
From the above, the limit state is now calculated:
kmod Fk
Flim.u � � 5.71kN
� m� f
This is compared to the centrifugal load FzB of load case E, which is 5.25 kN.
FzB �
Flim.u
(F.2)
(F.3)
(F.4)
185