Orientation Mapping in Fibre Materials
Fibres can supply extraordinary strength to plastic materials – depending on how they mix, match, and align. LINX is mapping fibre orientation, linking it to processing.
One of the easiest ways to commercially produce plastic components is by injection moulding – i.e. forcing molten plastic into a mould, which defines the desired shape of the component upon cooling. A variety of injection moulding which became popular in recent years uses plastic with embedded fibres. Such fibre-reinforced plastic can be extraordinary strong, and fibre-reinforced components increasingly replace metal components, e.g. in the car industry. However, the superior properties of the fibre-reinforced plastic only manifest themselves if the fibres are suitably arranged. Poor fibre orientation can cause up to 80 % loss of material strength compared to a theoretical maximum achievable if fibres are well oriented.
The relationship between an injection moulding process and the fibre orientations which it induces is complicated. As such, improving product production to achieve appropriate fibre arrangement is both time-consuming and costly. The difficulty owes greatly to the lack of analytical tools which can accurately estimate fibre orientation in 3D and thus help build libraries of cause-and-effect within the field.
In this project, LINX makes a concerted investigation into new promising ways of determining the orientations of fibres in fibre-reinforced plastic components.
Techniques and Methods
The orientation of fibres in fibre-reinforced materials greatly influences material properties, like strength or stiffness. Therefore, a controlled orientation of fibres is desired for application, which implies high demands on production processes. Varying production parameters and testing the product afterwards is time- and cost-intensive, which is why simulations are used to obtain information about the desired parameters beforehand. However, conventional simulations using pre-set structural information do not necessarily show the same results as laboratory tests and thus need to be optimized. To improve simulations and to verify the obtained results, non-destructive determination of the fibre orientation can be used as an input for simulations.
Two different types of geomotry for samples have been studied,
- one system with a complex structure in which the aim was to study the fibre orientation and thereby the fibre behavior in the injection molding flow. The study has been mainly on a visual part to see the fibre flowlines at given interesting positions in the structure. Another part of the fibre behaviour study was to investigate if long fibres break in complex structures.
- The other type of geomotry was a more simple structure in which the aim is to compare the investigated fibre orientations with simulations of the fibre orientations. Either by single point comparison using high resolution X-ray tomography or comparison over larger volumes using X-ray tomography with lower resolution.
The project has so far provided visual information into the complex stuctures showing how the fibres are located in the flowlines. Several different samples were investigated using the method, where the samples were produced with different plastics and different fibre lengths. Recommendations for futher progress in determining fibre lenght in the samples has been layed out.
In the work with comparing simulated fibre orientations with measured orientations, visual inspection showed mostly an agreement between the simulated data and the measured orientations. But the investigation also revealed areas with differences. The work of quantifying the measurement and using the results into new simulations continues in 2019.
Participants: Grundfos, Xnovo Technology, VELUX, Technical University of Denmark.
Start date, end date: July 2017 – present
Title: Orientation mapping in fiber matrials (FP07.003, Fiber structure and dynamics).