The image below shows a unit which was part of an cooling installation which functioned as the cooling of the radar installation of a navy defence installation. Due to resonances in the frame, and the resulting movement of components relative to each other, the alignment between electro motor and compressor was severely stressed. This was partly resulting from wrongly selected rubber supports.

The occurring vibrations, which occurred as a result of resonance of the frame, considerably lowered the  life cycle of the bearings of the compressor, and caused repeated malfunctioning of the system. Since the installation was part of the ship's defence system, they were not too happy with the situation, and engaged our services in order to solve the problem. A modification of the rubber elements was all what was needed to restore the reliability of the installation. In order to prevent this from happening, the properties of the mounts, in combination with their distribution and the total mass of the frame, must be carefully selected.

At least, a 6 degrees of freedom calculation (6 D.O.F.) should be made. However, this way, only the lowest modes, i.e. the modes in which the set moves as a whole on its feet, are calculated. Quite often, this is enough. However, in numerous cases we found that the frame itself can show resonances as well. This requires a more thorough modelling, using finite element calculations. The example left is an example of such a computer model.

With this model, the frame is not treated as a rigid body, allowing the calculation and vibration behaviour of local deflections as well.