PinfieldChallis 2011 JPhysConfSer.pdf (688.44 kB)
Download fileModelling the backscatter from spherical cavities in a solid matrix: can an effective medium layer model mimic the scattering response?
conference contribution
posted on 2012-12-04, 16:29 authored by Valerie PinfieldValerie Pinfield, Richard E. ChallisIndustrial applications are increasingly turning to modern composite layered
materials to satisfy strength requirements whilst reducing component weight. An important
group of such materials are fibre/resin composites in which long fibres are laid down in layers
in a resin matrix. Whilst delamination flaws, where layers separate from each other, are
detectable using traditional ultrasonic techniques, the presence of porosity in any particular
layer is harder to detect. The reflected signal from a layered material can already be modelled
successfully by using the acoustic impedance of the layers and summing reflections from layer
boundaries. However, it is not yet known how to incorporate porosity into such a model. The
aim of the work reported here was to model the backscatter from randomly distributed
spherical cavities within one layer, and to establish whether an effective medium, with a
derived acoustic impedance, could reproduce the characteristics of that scattering. Since
effective medium models are much more readily implemented in simulations of multi-layer
structures than scattering per se, it was felt desirable to simplify the scattering response into an
effective medium representation.
A model was constructed in which spherical cavities were placed randomly in a solid
continuous matrix and the system backscattering response was calculated. The scattering from
the cavities was determined by using the Rayleigh partial-wave method, and taking the
received signal at the transducer to be equivalent to the far field limit. It was concluded that
even at relatively low porosity levels, the received signal was still “layer-like” and an effective
medium model was a good approximation for the scattering behaviour.
History
School
- Aeronautical, Automotive, Chemical and Materials Engineering
Department
- Chemical Engineering
Citation
PINFIELD, V.J. and CHALLIS, R.E., 2011. Modelling the backscatter from spherical cavities in a solid matrix: can an effective medium layer model mimic the scattering response? Journal of Physics: Conference Series, 269, 012016.Publisher
© IOPVersion
- VoR (Version of Record)
Publication date
2011Notes
This conference paper was published under licence in the Journal of Physics: Conference Series by IOP Publishing Ltd. It was delivered at the 6th Groupe De Recherche 2501 and 9th Anglo-French Physical Acoustics Joint Conference.ISSN
1742-6588eISSN
1742-6596Publisher version
Language
- en