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10.12 Function definitions
10.12.1 Average acceleration with frequency weighting W
m
and
evaluation time T
a
Wm
R.M.S. value of acceleration expressed in m/s
2
, defined by:
2
1
T
0
2
Wm
Wm
)d
(
a
T
1
a
⎟⎟
⎠
⎞
⎜⎜
⎝
⎛
=
∫
t
t
a
Wm
(t):
instantaneous acceleration based on the time t and with frequency
weighting W
m
, in m/s
2
T:
duration of the measurement (evaluation)
10.12.2 Acceleration level
L
Wm
R.M.S value of acceleration expressed in dB referred to 10
-6
m/s
2
, defined by:
o
Wm
a
a
log
20
L
Wm
=
a
Wm
:
average acceleration with frequency weighting W
m
, in m/s
2
a
o
:
reference acceleration 10
-6
m/s
2
10.12.3 Peak acceleration
PEAK
Module
maximum value of the instantaneous acceleration defined by:
( )
[
]
T
t
t
Wm
t
a
=
=
=
0
max
PEAK
a
Wm
(t):
instantaneous acceleration based on the time t and with frequency
weighting W
m
, in m/s
2
T:
duration of the measurement (evaluation)
10.12.4 Crest factor
CF
Quotient between the peak acceleration and the RMS acceleration.
10.12.5 Maximum Transient Vibration Value
MTVV
Maximum value of the acceleration with the frequency weighting W
m
and with
slow exponential averaging (
τ
= 1 s) in the evaluation time T. Expressed in m/s
2
.
