The Role of Friction in Tow Mechanics
University of Twente
Faculty of Engineering Technology
Chair of Production Technology
P.O. Box 217
7500 AE Enschede
Room N128, “Horst” building
Phone : +31-53-489 4346
Start / End:
December 2008 to December 2012
Stichting Technologie en Wetenschap
The general aim of this PhD research project is to provide a thorough insight in the physical background of the frictional behaviour of fibrous tows.
Composites forming processes like resin transfer moulding (RTM) typically involve a preforming step in which dry fabric material is deformed. Frictional forces in tool-fabric and fabric-fabric contacts determine the fabric deformation behaviour to a large extent. The frictional behaviour of the reinforcements is anisotropic and pressure dependent, due to the geometrical and material properties of the fibrous constituents.
Most fibre composite reinforcements are manufactured from tows of 1000 up to 48000 or more filaments. Previous investigations of the frictional behaviour of fibrous materials were mostly performed on a particular scale, i.e. the mesoscopic tow scale, or the macroscopic fabric scale. A continuum approach is then often necessary to represent the material simulations of the deformation behaviour. The deformation of dry or pre-consolidated fabrics during the production process is usually described in a continuum formulation as well. For a first approximation this may be a reasonable assumption. However, when looking closer at the deformation mechanisms, this approach is inaccurate.
This study aims to provide a qualitative and quantitative relation between the microscopic filament friction and the effects on the macroscopic scale. The mesoscopic frictional behaviour of tow materials provides the link between the aforementioned scales. An experimental setup based on the capstan effect is employed to measure the frictional behaviour of fibrous tows in contact with each other and metal counterfaces. A theoretical model based on contact mechanics is developed to describe the measured frictional behaviour of fibrous tows.
Figure 1: The hierarchical multi-scale representation of textile reinforcements in composite parts.
Figure 2: Detail of the capstan friction setup to characterise the frictional behaviour of fibrous tows.