A
y
(
8
)=
√
1
T
0
∑
i
=
1
n
a
wyi
2
T
ei
Equation 5
A
z
(
8
)=
√
1
T
0
∑
i
=
1
n
a
wzi
2
T
ei
Equation 6
where
A
x/y/z
(8) are the daily exposures of directions X/Y/Z
a
wx/y/zi
are the energy equivalent mean values of the frequency weighted accelerations
in the directions X/Y/Z during partial exposure section i with the following
frequency and magnitude weightings:
- X and Y with weighting filter Wd and weighting factor 1.4
- Z with weighting filter Wk and weighting factor 1.0
n
is the number of partial exposure sections
T
ei
is the duration of exposure i
T
0
is the reference duration of 8 hours
The calculations shown above are based on RMS values. An alternative method
uses fourth-power mean values called
Vibration Dose Value (VDV)
with the mea-
suring unit m/s
1,75
. Table 1 also includes VDV based limit values.
VDV based daily exposure VDV(8) is calculated:
VDV
(
8
)=
VDV
⋅
4
√
T
exp
T
meas
Equation 7
where
VDV(8) is the daily exposure value
VDV is the frequency-weighted vibration dose value
T
exp
is the duration of exposure
T
meas
is the duration of VDV measurement
Daily exposure may consist again of several partial exposure sections. Separate
daily exposure values are to be calculated for X/Y/Z. The highest one is compared
with the limits of Table 1 for evaluation.
VDV
x
(
8
)=
4
√
∑
i
=
1
n
VDV
xi
4
⋅
T
iexp
T
imeas
Equation 8
VDV
y
(
8
)=
4
√
∑
i
=
1
n
VDV
yi
4
⋅
T
iexp
T
imeas
Equation 9
VDV
z
(
8
)=
4
√
∑
i
=
1
n
VDV
zi
4
⋅
T
iexp
T
imeas
Equation 10
where
6