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The University of Southampton
Engineering

Research project: Variability and uncertainty in vibroacoustics

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Variability can be naturally occurring differences between nominally similar objects, e.g. cars, mechanical components etc. and such differences are exhibited at the mid to high frequencies. Uncertainty covers the issue of missing information, be it material or geometric properties, or predictions and models which can be in error. The main objectives are measuring and quantifying such variability and uncertainty and then having the means to incorporate it into vibroacoustic predictions.

of the interior noise n the 1 kHz third octave band and across all the vehicles and frequency range for the diesel cars
Statistical variation
Characteristics in the 50 Hz third octave band fitting a Gaussian distribution
Vehicle noise transmission

Automotive structure variability
A large study of the noise transmission on similar new cars from the exterior to the interior of cars and the interior noise due to engine and tyre sources has been conducted.

 

 

 

and forced vibration response predictions for a missing weld
The spot weld model
and validation of the predictions (right) for a simple welded structure using variabillity in the unwelded components
Experimental measurements (left)

Variability in spot welded structures
A model for the spot weld is included into a component model which allows predictions to be made when either welds are missing or where the location or size are variable.

 

 

 

using light transmission, to stiffness variation using a rule of mixtures
Area density,
simulations (Monte Carlo) to get the natural frequency statistics over a large number of samples with random material stiffness
Subsequent Finite Element (FE)

Spatially random material variability
Using optical light transmission the density of the fibres for a glass fibre plate can be estimated and related to the stiffness. A random field for the latter is developed and then used in a predictive model to estimate natural frequency statistics.

Related research groups

Dynamics Group
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