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Updated journal, conference papers
January 2018
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Updated research project information
March 2017
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Recent academic peer reviewed journal papers
January 2017
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Updated contact information and job title
December 2016
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Updated user manual for acoustic boundary element solver
November 2016
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This page provides an overview of some of the research topics of interest.

Automotive

The design of automotive components is increasingly concerned with increasing quality through the life of the vehicle, through reductions of tactile vibration and noise. Structure-borne noise is generated by moving components, transmitted through joints and suspension frames into the passenger compartment.

In the design process it is important to take account of the natural frequencies of each of the components so that coupling between the structural resonances and acoustic radiation is minimised.

The research carried out into the minimisation of panel vibration and acoustic radiation, coupled with fast and efficient methods to determine optimised natural frequencies and mode shapes of complex panels can be used to assist in this design process.

For inside the vehicle, one particular design problem is that each manufactured component is slightly different, with tolerances, assembly variability and environmental effects. Design based on deterministic numerical prediction is therefore challenging, while non-deterministic and statistical solutions tend to neglect important coupling information such as phase between resonances, through averaging and smoothing

The noise from automotive vehicles has mostly reduced over the past decades (engine, exhaust and air intake sources). However the noise from the interaction of the tyres with the road has increased, partly as a result of larger diameter and wider tyres driven by increasing weight and performance requirements.

As a result, above approximately 35 miles per hour, the tyre / road interaction noise is dominant and is of significant importance during acceleration.

Due to future legislative restrictions, especially in urban environments, the importance of research tools which can assist in the design process have become apparent.

Noise sources during vehicle acceleration

Aeronautical

The design process for aeronautical craft are concerned with the efficient and effective minimisation of structural vibration with the least damping material possible. Traditional vibration damping methods include the application of viscoelastic material to a panel, which converts flexural kinetic energy of the panel into heat inside the damping layer.

Traditional vibration damping by extensional damping

Although these traditional methods can be made more effective through the use of constraining layers, multiple damping layers and edge damping, the overall effectiveness is limited and these do use a significant amount of damping material.

The research carried out optimises the vibration damping whilst minimising the mass addition through the use of damped profiled indentations in structural plate surfaces. As the bending stiffness of the plate is altered, for example by creating a power-law profile of thickness in the plate, the composite loss factor can rise considerably.

In addition to the optimisation of damping loss factor in order to minimise the vibration, research has been carried out into non-destructive evaluation of crack propagation using Lamb waves at higher frequencies (ultrasonic) through inhomogeneous materials. For example, where a panel has variable thickness or material properties, how to identify any potential problems without dismantling the whole structure for inspection.

Environmental noise pollution

In the UK, the pollution from noise can be measured through surveys of how irritated people are in their local area. One such survey has been published by DEFRA, which indicates that road traffic noise adversely affects peoples quality of life. There have been studies linking environmental noise pollution to increased levels of stress and blood pressure, in addition to a lack of quality sleep.

The second largest problem indicated is the presence of other people, which will become a more significant problem as larger populations live in higher density urban areas. If you happen to live near to an airport or train line, then this intermittent noise can be particularly disturbing.

The noise can be reduced from each of these areas by identifying and reducing the noise at the source, or by interfering with the transmission path. Examples of the latter include structural partition walls which shield the listener from some frequencies or damping barriers which attempt to attenuate some of the acoustic energy.

Sources of noise nuisance

Building vibration and acoustics

A pleasant and productive office relies on a minimum of background noise, however the trend in recent years has been the use of open plan offices. In order to reduce the noise, it is possible to use specially designed partitions in order to attenuate the acoustic energy. Patents for low noise structural panels are in development.

Last updated February 2014

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