As experienced vibration consultants - why you should speak to us first!

Reasons to use us as vibration consultants

  • we have over 25 years experience in vibration in various industries

  • we are chartered engineers in both mechanical engineering and acoustics

  • with reference to vibration engineering,

    • we instrument structures, machinery and equipment with accelerometers and strain gauges

    • we investigate fatigue and vibration related failures

    • we record vibration data

    • we analyse vibration data

    • we update numerical models to recorded vibration and strain data

    • we design products and machinery to operate in vibration environments

    • and improve them to operate reliably and resiliently in its surrounding environment

    • we vibration test and develop products

All these reasons for using us as your vibration consultant, is backed by extensive experience and expertise. Every project that we have completed, was a challenge, and we provided the solution.

What is vibration?

Vibration of a particle, object or body is movement back and forth about a position of equilibrium.

(an object is in equilibrium when a state of rest or the sum of external forces exerted on the object equals zero)

Why is there so much emphasis on vibration?

Here are a few key facts about vibration and why we chose to specialise in vibration:

  • source of noise

  • fatigue cycling has the same frequency as vibration present in the structure

  • it can be detrimental to product health

  • high levels cause health problems to humans

  • is a design challenge for new products in vibration environments

These are the main reasons why we focus of vibration measurements and vibration control. Throughout this website, you will appreciate that everything we do, will relate to vibration in some shape or form.

Why do we focus on vibration?

Here are a few key facts about vibration and why we chose to specialise in vibration:

  • Vibration is the source of noise and sound, and is the origin for the study of structural dynamics.

  • Vibration control suppresses unwanted vibration, structural behaviour, noise and sound.

  • Vibration is linked to all the above and acoustics, especially in the field of vibro-acoustics and building acoustics

These are the main reasons why we focus of vibration measurements and vibration control. Throughout this website, you will appreciate that everything we do, will relate to vibration in some shape or form.

Mechanical Engineering that ensures your product passes vibration testing

For many years we have conducted vibration testing of products. Many products failed on test for a variety of reasons.

This experience has given us expertise in designing products for the vibration environment. This knowledge and experience is what you need to pass your vibration test.

So, are performing vibration testing on a product? Is it failing on a vibration test? Are you concerned about the cost of continuing? Then give us a call on 01908 643 433 for help.

Vibration measurements, assessments and surveys

Vibration is usually measured with an accelerometer, which measures physical acceleration at its location. It is recorded and analysed with an FFT (Fast Fourier Transform) analyser, which converts the oscillations from the time domain to the frequency domain.

From this measurement and analysis, the magnitude and the frequency of the vibration is now known at the accelerometer location.

The magnitude of vibration only is usually used for assessments of levels to which people and structures are exposed. And is typically used as exposure limits, i.e. human vibration exposure, or building vibration levels etc. These are typically accompanied by time durations to which the person can be exposed.

We perform vibration assessments and surveys like these above, on buildings, large structures, machinery and equipment.

Human exposure

Exposure to high mechanical vibrations for too long a period results has health effects on humans, and can lead to adverse medical conditions. Medical conditions like whole hand arm and body vibration. (Hand-Arm-Vibration-Syndrome is also known as white finger or white finger syndrome.)

The Vibration at Work Regulations 2005 has more information on the exposure limits and durations. Companies should reference this regulation for safe operation of equipment. The HSE enforces this regulation, and the employer should enforce it too.

The European Physical Agents Directive 2002/44/EC also prescribes minimal exposure requirements. Enforced throughout Europe.

The regulations introduce an:

  • exposure action value of 2.5m.s-2 A(8). This is the level at which employers should introduce technical prevention measures.

  • exposure upper limit value of 5.0m.s-2 A(8). Do not exceed this limit.

If equipment or machinery have unfavourable vibration levels, we can improve, redesign and refine the equipment to have more favourable behaviour.

Please see our engineering services for further information

Engineering for the environment

If you are familiar with environmental testing, i.e. aerospace certification, you will understand why our strap line is "engineering for the environment!"

Our engineering experience is in designing and improving products to:

  • operate resiliently and unnoticed in the natural environment, and

  • operate robustly and reliably in the extreme environment

To understand the terms natural and extreme environments, please click on the buttons hereafter for a more in-depth discussion.

Engineering for extreme environments

To design and engineer products for an extreme environment, the vibration levels must be known.

Once the vibration levels are known, and or defined, the design work can start. By alternating frequently between the structural analysis of the design and the design itself.

Click on the relevant button below for more information on how we improve the structural dynamics of equipment in a vibration environment and our engineering services.

Vibration Testing

We have been involved in vibration testing since 1996. Our primary involvement is in

  • overseeing testing

  • report on test results, the state of the equipment and

  • how to improve the design

We've gained much knowledge in vibration testing. Therefore, we have included several case studies and lessons learnt on the vibration blog page of this website.

Often, our involvement with a customer starts when a product does not pass a test. This usually increases the cost of the project. We thus urge you to get us involved as soon as possible.

We have overseen certification testing in several industries. We have seen conformity and failures. From the latter, we have found the reasons, and urge you once again to get us involved as soon as possible.

Why is there so much emphasis on vibration?

Vibration as the source of noise

Noise is ever present in our daily lives, and is the source of sound and noise. The audible spectra for humans is between 20Hz and 20kHz. If the sound levels are very high, it becomes health threatening to humans.

(Different animal species are susceptible to frequency bandwidths broader than that for people. Hence, justifying the importance of mitigating noise levels emanated in the environment.)

As the source of noise, mitigating noise levels can be through control. Designing vibrational surfaces to vibrate at lower amplitudes, will mitigate noise.

We have investigated noise sources in housing, construction and in the automotive industry.

Our work includes measurement, assessments, analysis, modelling, bench marking and design. Here are a few brief descriptions of our work:

  • finite element modelling of structures in vehicles to reduce noise radiation

  • transfer path analysis

  • BS 8233
  • bench marking of vehicles to understand their NVH and dynamic behaviour

  • acoustics measurements for residential and commercial dwellings

  • structural measurements, experimental modal analysis on the physical system to determine natural frequencies and mode shapes, to understand at which frequency the resonances occur, updating of the model etc.

Assessing the environment

When the intensity is unknown, we assess the environment through measurements.

The measurement data collection process is intrusive. As we will instrument the structure or environment to determine the frequency content and levels thereof. We'll consider the corresponding frequency range to understand the noise implications, and process the data.

Analysis of this data will support our decision of any mitigation actions required

Vibration isolation using anti-vibration (AV) mounts

Vibration isolation can only truly be confirmed with vibration measurements either side of the isolation mechanism, i.e. AV mounts or anti-vibration mounts, to determine the vibration transmitted through the AV mounts.

for this, the amplitude and frequency is not adequate. The phase angle of the measurements on either side is important. As it is pertinent to know the direction of the motion on either side of the mount; whether it is in phase or out of phase in order to understand the exact transmissibility.

But the motion could originate from structural bending and is discussed on the structural dynamics page

Vibration Analysis of Rotating Machines

Why we focus on rotating vibration?

The unbalance of the rotor in rotating equipment causes vibration throughout the unit.

Definition of unbalance on a rotor

Unbalance of a rotor will occur when a rotor or a component mounted on a rotor has a mass centre (or centre of gravity, i.e. COG) that is not coincident with the axis of rotation [1]

Unbalance of a rotor is when the centre of gravity of the rotor does not coincide with the axis of rotation. Thus causes an off-balance.

The unbalance force and frequency dependents on the rotational eccentric mass and speed.

To balance a rotor to have no eccentric mass is impossible. But striving for the most perfect balance for a rotor is direct proportional to the cost of doing so.

This is why vibration isolate is necessary; to stop the vibration transmitting elsewhere. And to isolate any surfaces from vibration to mitigate noise radiation.

You can read more on vibration isolation and noise radiation on this site.

How to design for vibration environments

We improve equipment and machinery by design to quieten or lessen the noise radiated from all products, equipment and machinery. We refine products so that they are less harmful to the operator and less noisy to the surroundings.

We minimize noise pollution to protect the environment. Not only to meet industrial standards, regulations and legislations; because it is the right thing to do.

We are able to help with design for a vibration environment at any stage of the product evolution. We can support you from assessments, through to testing of your products.

We are more than just vibration consultants

Our vibration consultant experience has groomed us to work with other engineering disciplines. We understand the frustrations and challenges that other engineers face.

You'll always get more than just vibration consultants from Environmentally Sound Limited.

We are mechanical engineers in product design and failure investigation, and acousticians. Our service is what you want.

References

  1. Friswell, M., Penny, J., Garvey, S. and Lees, A. (2010). Dynamics of Rotating Machines. Cambridge University Press.
  2. Fundamentals of Sound and Vibration, Frank Fahy and David Thompson