Vibration measurement and calculation

Vibration measurement

Simultaneous measurement of noise and vibration can help determine which machines are annoying and which are not. The noise may be due to a combination of the machine's high sound output, low sound absorption around the machine and poor acoustic insulation in the building. The noise can also be caused by vibrations which is transmitted from the machine to the building's walls, which radiate sound everywhere. Noise and vibration measurements should be able to determine what kind of transmission is dominant.

Frequency analysis

Frequency analysis reveals the type of vibration isolation needed. If there are only one or two machines that can cause vibrations and noise, then it is often cheaper to improve vibration isolation than to carry out noise mapping.

Troubleshoot existing installations where problems with noise or vibrations have been identified. Here it may be helpful to look at the frequency analysis and the timing signal simultaneously. Including signal from a press.

Vibration over and under existing vibration isolators with the plant in operation reveals whether they are effective or not.
Vibration along the pipe connections on the compressors (or other machines) shows whether the connections are sufficiently flexible, or whether it is necessary to hang up flexible tubes in order to isolate them from the building.

Calculation of vibration isolation

The easiest and cheapest vibration isolation is achieved when the system is symmetrical on three axes. The symmetry reduces the coupling of vibrations in different directions.
We provide free vibration calculations for systems, where each anti-vibration damper carries the same load. The solution is simple, as the solution can be found for a single vibration mode at a time.

Example of calculation of a simple equipment set up.

The calculation demonstrates the efficiency of a selected vibration isolation with the chosen damping materials. It provides an easy opportunity for comparison of different solutions.

Efficiency of vibration isolation

If a system is constructed without concern for symmetry, placement of the centre of gravity and load distribution between damping materials, then calculations will take longer, and more data about weight distribution will be required before an effective solution is found. The solution requires determination of total 6 mode conversions.

The effects of double vibration isolating can also be calculated using a double mass system. A double-action system, for example, consist of a compressor which is set up with vibration inhibitors on a frame, which in turn is vibration isolated from the floor. An accurate calculation requires good knowledge of component masses and mass moments of inertia. The solution requires a total determination of 12 double mode conversions.