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, assessemnts, 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 modeshapes, to understand at which frequency the resonances ocur, 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
Adverse medical conditions are casued by exposure to high mechanical vibrations for too long a period; 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 vibration exposure. 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 prescribes minimal exposure requirements. Enforced throughout Europe.
The regulations introduce an:
- exposure action value of 2.5 m/s2 A(8). This is the level at which employers should introduce technical prevention measures.
- exposure upper limit value of 5.0 m/s2 A(8). Do not exceed this limit.
Control by design and improvement
To quieten equipment and machinery, we design, develop, improve and test machinery. We refine the products so that they are less harmful to the operator and less noisy to the surroundings.
We minimize polution 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 vibrational environments at any stage of the product evolution. We can support you from assessments, through to testing of your products.
We perform structural dynamic assessments on existing and problematic equipment. This assessment will include modal testing to identify the natural frequencies and modeshapes. (eigenvalues and eigenvectors). Using the results of the experimental analysis, we'll update the analytical structural model.
We use established methods to analyse the structural model. Once determining the actual dynamic behaviour, we will update the analytical model. Then verify its behaviour to establish similarities.
Our experience includes measuring, assessing and analysing structural dynamics on:
- construction sites
- offshore structures
- large off-highway vehicles
- mine shaft lifts/skips
- articulated truck trailers
- aeroplane engine cradles
- jet engine bending modes
- vehicle dynamics
- design for vibrational environments
We provide corrective actions and recommendations to improve your product. We will propose the most sound measures. That will have minimal financial and time impact on your project and company.
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.
Commissioning of the product
We finish our work with a report of the test. This includes conclusions and recommendations.
If you have a reliability problem caused by any environmetal element or condition, we are here to help, so please contact us.