Vibration isolation to reduce noise and vibration

INTRODUCTION TO VIBRATION ISOLATION

Mechanical vibration isolation is common with mechanical equipment and machinery. Like rotating equipment, i.e. pumps, electricity generators, internal combustion engines etc.

As mechanical engineers, we are very experienced in reducing noise and vibration by design. We engineer solutions to reduce vibration transmission by optimising its structure.

But sometimes it is necessary to isolate mechanical vibrations from transmitting into neighbouring structures. This we achieve by using isolation mounts and isolation systems.

Our experience of mechanical vibration isolation?

We are very experienced mechanical engineers in the field of vibration. In designing for vibration environments to certifying equipment to withstand vibration.

Our experience is in industrial, automotive and the aerospace industries. All in which unwanted vibration and structural vibration is not tolerated. This experience has honed our skills in designing machines and equipment to withstand vibration. Many of which had to withstand vibration without any isolation systems.

This experience and expertise make us proficient in mechanical vibration isolation.

WHAT IS MECHANICAL VIBRATION ISOLATION?

Vibration isolation is a mechanism of isolating a structure from the vibration source.

  • this could be to prevent unwanted vibration reaching fragile or sensitive equipment, like in extreme or demanding environments, or

  • to prevent vibration getting into structures. Like large air conditioning units isolated from the building itself, as the transmitted vibration can become structure borne.

For example, a car engine is isolated with anti-vibration mounts. Isolated from the chassis of a car to prevent the magnitude of the engine vibrations reaching the car chassis.

If the isolation mounts weren't installed, the car chassis would fatigue. And the cabin would be noisier due to structure-borne sound and noise radiation.

How do we isolate machines from transmitting unwanted vibration?

Our experience in vibration started with designing equipment and electronic instrumentation to survive in extreme vibration environments and was achieved using vibration isolation mounts and without using vibration §isolation mounts. There were several times that we wanted to use anti-vibration mounts. But it was not permitted. (As everything must stay intact during crash safety testing).

Hence, we are very experienced in designing for vibration environments, and more experienced at designing for vibration. Especially when it involves optimising Structural Dynamics of a product.

However, when preventing structure-borne sound and vibration transmitting into buildings and structures, isolation is less expensive and more practical.

Where it all started

It's easy to find the isolation efficiency of a one degree of freedom mass and spring model. But when it is a structure with several degrees of freedom and many mounting points, more aspects must be considered. It is not just the mass, moments of inertia and vibration source that must be considered. It is the structural dynamics of the entire structure that must be considered.

This is where our extensive experience in structural dynamics benefits the installation. Our ability to create dynamic models of structures is necessary in predicting the isolation efficiency.

With so many different support structures used in building auxiliary equipment, it is pertinent to understand the structural behaviour.

Understanding the detailed structural behaviour before isolating the vibration source from the building, ensures that the correct isolation mechanism is fitted.

It's a complex system

It's the structural dynamics of the entire structure and how it behaves that is the true challenge. The structural dynamics of the structure itself is what dictates how the motion at different mounting locations.

For example, imagine a diesel electric generator that is mounted on a frame. A frame that is isolated from the ground.

But, for some reason the vibration was transmitted to the ground. But the isolation mounts were specified for that generator weight and vibration content?

The reason for the vibration passing through the vibration mounts, was that the frame was abnormally flexible. Which generated higher amplitude vibration than expected.

TThe vertical displacement at two of the mounts were very high at certain frequencies. And the vibration isolation mounts were not effective. Thus, allowing the vibration to pass through the isolators. resulting in inadequate isolation efficiency.

It is the field of structural dynamics and modal testing that is pertinent to resolve this issue. This enabled us to modify the frame and isolate vibration from transmitting into the ground.

Structural modelling, model updating and analysis of complex structures

With thorough vibration measurements, shock loading or modal testing, we can model the structural dynamics of structures.

We instrument the structure with the necessary transducers, record the vibration, and analyse the data.

Once mode shapes are achieved, a numerical model of the structure is updated to mimic the actual structure.

This model is then compared to the actual structure. And checked that the model behaves like the physical structure. Once the structural behaviour matches, we manipulate the mode shapes and natural frequencies to achieve a more favourable structural behaviour. A structural behaviour that can effectively isolate from the building.

Yes, this is a thorough approach. But progress is communicated. And when complete it will be the physical recorded data and improvement evidence that will put you at ease.

As mechanical vibration isolation consultants, we have extensive experience in vibration control, structural dynamics, modal testing and noise radiation mitigation. As excellent knowledge and expertise are required for complex vibration problems.

All these are necessary to ensure vibration and any noise radiated from the equipment can be mitigated.

Vibration Isolators and isolation systems

From natural rubber mounts to isolation systems, we can install efficient isolation mechanisms by controlling the transmission of vibration. even at very low frequencies

We have established a network of isolation mount suppliers that can supply the most appropriate isolation mechanicsm for the most effective result.

For more information on Vibration Isolation

Environmentally Sound Limited are vibration and noise consultants, as well as mechanical engineers. We have dealt with unwanted mechanical vibration in several industries for over 25 years.

If you need help with mechanical vibration isolation, call us on 01908 643433.


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