Towards the development of an instrumented test bed for tufting visualisation

This paper presents the development of a test bed for tufting as Through-Thickness Reinforcement (TTR). The setup provides understanding of quality implications of TTR processing parameters on composite sandwich panels. The main parameters are identified from a commercial TTR machine, then recreated in a test frame with a transparent rig containing the compacted preform, allowing visibility of tuft formation. Initially the needle is observed alone, inserting into and retracting from the preform at controlled rates, and resulting damage is detected with imaging techniques. Thread is then added to observe tuft formation. Damage is found to comprise fragmentation of both the carbon fibre skin and foam core, and non-uniformity of the needle path dimensions. A prototype ‘quality matrix’ is developed, establishing a possible ideal tuft, i.e. uniformity and minimal preform disruption. Results suggest some correlation between improved as-measured tuft quality and insertion rate, potentially allowing greater control of component macro-mechanical properties.