The effect of pick-up point location on fibre angle devation in Non-Crimp Fabrics

For pick-and-place processes to become widely implemented in industry a consistent and acceptable product quality needs to be achieved. One important quality criterion is the fiber angle deviations in the reinforcement. Handling a reinforcement will subject it to forces due to e.g. gravity and accelerations. These forces can result in in-plane shear and subsequently in fiber angle deviations. The current work looks at predicting and preventing in-plane shear induced fiber angle deviations by studying the positioning of pick-up points. In the state of the art the positioning of individual pick-up points is typically either not discussed or is based on the mould where the fabric is to be draped on – not on the effect of the handling on the fabric. The relationship between the positioning of the pick-up points and the behavior of the fabric should however also be considered. Finite element simulations validated through experimental work will be used to study the influence of pick-up point location on the in-plane shear strain for a bi-axial Non Crimp Fabric [NCF]. In [1] tolerances have been set for the fiber angle deviations, additionally the relationship between in-plane shear strain and fiber angle deviations has been demonstrated for the specific NCF. These results are used in the present work to evaluate the results from the simulations. The current work will demonstrate that it is possible to control the in-plane shear induced fiber angle deviations by varying the position and number of the pick-up points. Additionally, It will show whether simulations for the positioning of pick-up points on large reinforcements can be simplified by looking at one instance of a repeating pattern. The paper will provide a framework for the determination of positioning of pick-up points while predicting and preventing in-plane shear induced fiber angle deviations.
Delft Aerospace Structures and Materials Laboratory
Aerospace Structures & Computational Mechanics
Structural Integrity & Composites