The results of the project demonstrated that with appropriate signal processing, the presence of small holes, small area delaminations and impact damage of a few Joules could be detected in both plate samples and more complex structures representing typical assemblies used by the industrial partners. The experimental assessment was complemented by analytical modelling from which the extrapolated trends indicated that the system could also detect small cracks within a planar geometry. The sensitivity to these major sources of damage in composite structures was below the threshold required for integrity monitoring and whilst the signature analysis process was not targeted at damage location, the procedure demonstrated convincingly that the process could recognise the presence of damage within the structures which were assessed.
The results of the project also indicated that whilst the concept has substantial practical potential, significant improvements could be expected from enhanced data acquisition and processing algorithms which could emerge from future basic research. The prototype system developed in the programme was based upon laboratory instruments and the insonification and interrogation system, together with the data interpretation software, must be configured as a self contained unit prior to future exploitation.
The extensive use of composite structures for automotive, high speed trains, aircraft industries is hampered by the need for simple, reliable and quantitative methods for the detection, location and evaluation of externally inflicted damage and structural failure.
Such methods should be of low cost and allow real time evaluation of residual structural strength or permit simple assessments of the structures at predetermined intervals. They should also be used in the designf procedures to minimize time and costs needed for development.
The purpose of this project is to establish a new method for determining two and three dimensional maps of damage and failure in composite structures by using acoustic/ultrasonic probing of the structural properties.
The method will be implemented through built in acoustic/ultrasonic transmitters and small number of optical fibre sensors arrays, both being connected to an evaluation unit able to derive and interpret the data as maps of structure condition.
In the project, basic components and models shall be studied and evaluated through simple composites parts. Strategy of implantation and interpretation shall be derived and relevant components shall be developed and implemented in structures representatives of automotive,train,aerospace industries. Test completed in parallel with classical NDT methods will permit to assess the suitability of the method.
In all the three transport sectors, the availability of this techniques will permit significant saving in structure weight with attendant saving in structural cost and more important, in fuel consumption.
Funding SchemeCSC - Cost-sharing contracts
NE99 1LH Newcastle Upon Tyne
ST17 4LN Stafford
G1 1XW Glasgow