Some developments in testing composite materials

As part of a massive research project, Sirris studied the non-destructive testing of composites by active infrared thermography, the production of complex hollow parts in thermoplastic composites and the use of hemp biocomposites.

Fault detection in composites

As part of the FEDER Cilab project (Composite Innovation Laboratory) which is now completed, Sirris studied the non-destructive testing of composites by active infrared thermography. This technique consists in heating the material, studying the propagation of heat in the part and revealing by infrared camera any discontinuities of the thermal profile related to the presence of faults. 

To improve the method's sensitivity, Sirris developed an innovative technique based both on the uniformity of heating of the composite being examined and on the optimisation of the mathematical image processing. 

The main findings of the project are:

  • Dynamic heating of the composite by using a moving linear heat source and localised thermal flow very near the surface 
  • Image processing by dividing into several separate sub-segments and then recombining in a single temporarily discontinuous view, but summarising the best of each analysed sub-segment.

Dedicated software was developed to manage this data. The last phase of the project enabled this tool to be finalised and various functionalities to be added including the possibility of managing particular zones of the IR image rather than the whole image. Corrections were added to further improve image uniformity and homogeneity. 

These improvements reduced analysis times by three. 

Modelling of composite machining  

Cilab project partner, Cenaero, was asked to model composite machining. Sirris profited from the experience obtained with its IR camera to visualise heating during machining with a view to collecting the information required for calibrating the thermal modelling software developed by Cenaero.

Hollow parts with complex geometry in thermoplastic composite

Centexbel finalised a technique of braiding reinforcing/thermoplastic intermingled fibres. Sirris studied the manufacture of tubular objects from these preforms. 

Biocomposites 

In order to make use of waste (hemp chaff) from the hemp sector developed in Wallonia, Celabor finalised a technique for creating a semi-product for use on a compounder. Sirris undertook to create compounds from these pellets with all the additives required to obtain an injectable product acceptable to the market. Sirris also characterised the injected parts (especially impact resistance) throughout the finalising of the process.  

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