WinGD X72DF - Lateral Vibration Types; H-Type Vibration; X-Type Vibration; Lateral Vibration - X-Type and H-Type

Marine Installation Manual 2021-08 6-7
6 Engine Dynamics
6.2 External lateral forces and moments
X72DF
6.2.1 Lateral vibration types
The resulting lateral forces and moments generate two different modes of lateral
engine vibration, the H-type and X-type vibration; refer to Figure 6-5.
The table of H-type and X-type vibration values is also provided in the link
below:
External forces and moments
Figure 6-5 Lateral vibration — X-type and H-type
H-type vibration
H-type lateral vibrations are characterised by a mode shape where both sides of
the top of the engine, the driving and free end, vibrate together, in phase. The lat-
eral guide forces (F
L
) result in a lateral moment, expressed as resulting lateral H-
type moment (M
LH
).
X-type vibration
X-type lateral vibrations are characterised by a mode shape where at the top of
the engine, the driving and free ends vibrate in counter-phase to each other. As
these resulting lateral guide forces create opposing axial moments at the two ends
of the engine, the X-type lateral vibrations are expressed as a moment around the
vertical axis, the resulting lateral X-type moment (M
LX
).
SM-0032
Resulting lateral X-type momentM
LX
=
M
LX
Resulting guide forcesF
L
=
Resulting lateral H-type momentM
LH
=
M
LH
+
-
F
L
+
-
F
L
+
-
F
L