Appendix E: Mechanical dynamic loading
154
Manual
DLoG MPC 6
20.2.
Using the device without vibration insulation (tuned to a
high frequency)
Selection criteria: Stationary, partly mobile or fully mobile applications for which
components offering insulation against vibrations cannot be used or are not required.
The DLoG MPC 6 system can vibrate and should therefore be
installed using the bracket as rigidly as possible.
With their variable mountings, the DLoG MPC 6 units form a spring-mass system that
can result in excitation by one or more random vibrations or shocks from its
surroundings.
This system reacts with natural oscillations, the amplitudes of which can be up to 20
times greater than the excitation amplitudes (resonance effects). The goal is therefore to
remove resonance points of this kind or at least to tune the system to such a high
frequency that they fall within the range of low excitation amplitudes.
For an initial assessment, you can test the device by hand. Bring the system to excitation
by gently hitting it with your hand. If the DLoG MPC 6 starts to visibly oscillate and if the
vibrations take a long time to die away, it is probable that the natural frequency is too
low. In this case, we recommend reinforcing the fixing points to the maximum bending
moments (through the use of rigid sections, for example).
Practically speaking, natural frequencies above 100 Hz are sufficient. However, those
below 50 Hz are likely to lead to damaging amplitudes during resonance which may
result in fatigue fractures along the outer mounting parts or on the internal electronic
components or even a loosening of the connections.
