Friction in composite forming processes
Start / End:
1st of September 2007 to 31st of December 2009
This project focuses on a specific type op composite: the Continuous Fibre Reinforced Polymer (CFRP). Or to put it in a less scientifically correct way: plastic with fibres. CFRPs consist of strong and stiff continuous fibres embedded in a polymeric matrix material. Well known fibre materials are glass, carbon and aramid. The polymer materials range from the relatively cheap materials, like polypropylene (PP), to high strength expensive materials used for structural component in the aeronautical industry, like PEEK. CFRPs are typically stiff, strong, corrosion resistant and have good fatigue properties.
An example of a project that would have been impossible without modern CFRPs is shown in the figure below. SpaceShipOne was the first private spaceship that flew out of the atmosphere in 2004.
A fast and cost effective production strategy is the stamping or pressing of products from pre-consolidated flat laminates. The pre-consolidated thermoplastic laminate is reheated and when the matrix material has melted, it is formed into the final three dimensional shape. Typical examples
of this production strategy are thermo-folding, diaphragm forming and rubber
pressing. These fast methods can produce large numbers of composite products in a cost efficient way, without compromising the structural strength and will contribute to the growing use of composites in the aerospace industry. The rubber pressing process is illustrated in the figure below.
The rubber pressing process. A flat laminate is reheated and formed between a steel and a rubber mould.
The main objective of this research is: optimization of thermoplastic composite products. Optimisation through a trial and error procedure usually results in an acceptable product, but with additional costs of labour, machine time and scrap products. Powerful numerical tools such as the finite element method (FEM) are capable of optimising the product in the design phase and in the ideal case they can lead to a first-time-right design. The optimisation loop is illustrated in the figure below.
Friction is an important phenomenon that can dominate the resulting product geometry, fibre orientations and fibre stresses upon forming. Two types of friction can be distinguished. The first type is tool-ply friction, which occurs between the tool materials and the outer plies of the laminate. The second type is ply-ply friction, which occurs on the interface between the individual plies of a laminate. A thorough understanding of the friction behaviour is necessary to make accurate predictions of product shapes after forming. We developed a novel experimental setup within this research to accurately measure friction in thermoplastic composites. This setup is shown in the figure below:
Both tool-ply and ply-ply friction can be measured with this setup. The key features of this setup are:
•temperature range: 20 - 500 °C
•normal pressure range: 1 - 100 kPa
•expected maximum normal pressure deviation: less than 5%
•laminate thickness measurement with an accuracy of 2 μm
The effects of temperature, normal pressure and sliding velocity on tool-ply and ply-ply friction can be measured with this setup. We expect the occurrence of hydrodynamic lubrication, which will result in the development of a thin film between the laminate and the tool. This thin film ranges from 5 to 100 microns and the measurements of the laminate thickness are accurate enough to detect these films.
Any questions? Have a look at my publications or send me an e-mail.
Hans P. de Bruijn, René H.W. ten Thije, Siegmund Johannes, Mastopexy with mesh reinforcement. The mechanical characteristics of polyester mesh in the female breast. Plastic and Reconstructive Surgery, 2009, in press.
R.H.W. ten Thije, R. Akkerman. Solutions to intra-ply shear locking in finite element analyses of fibre reinforced materials. Composites Part A: Applied Science and Manufacturing, Volume 39, Issue 7, July 2008, Pages 1167-1176
R.H.W. ten Thije, R. Akkerman, L. van der Meer, M. P. Ubbink, Tool-ply friction in thermoplastic composite forming, Proceedings of the 11th International ESAFORM conference on Materials Forming, Springer, Lyon, France, 2008
R.H.W. ten Thije, R. Akkerman, J. Huétink, Large deformation simulation of anisotropic material using an updated Lagrangian finite element method, Comput. Methods Appl. Mech. Engrg. (2007), p. 3141 - 3150.
R.H.W. ten Thije, R. Akkerman, Intra-ply shear locking, Proceedings of ESAFORM-10, Zaragoza, Spain, 2007, p.1017-1022.
R.H.W ten Thije, Finite element simulations of laminated composite processes, PhD thesis University of Twente, 2007, ISBN 978-90-365-2546-6.
R.H.W. ten Thije, R. Akkerman, J. Huétink, Large deformation simulation of anisotropic material, Proceedings of ESAFORM-9, Glasgow, UK, 2006, p. 803-806
R.H.W. ten Thije, R. Loendersloot, R. Akkerman, Drape simulation of non-crimp fabrics, 8th ESAFORM conference, Cluc Napoca (Romania), 2005, p991-994
R.H.W. ten Thije, R. Akkerman, Finite element simulation of draping with non-crimp fabrics, 15th ICCM conference, Durban (South Africa), 2005, on cd-rom
S.V. Lomov, M. Barburski, Tz. Stoilova, I. Verpoest, R. Akkerman, R. Loendersloot, R.H.W. ten Thije, Carbon Composites Based on Multiaxial Multiply Stitched Preforms. Part III: Biaxial Tension, Picture Frame and Compression Tests of the Preforms, Composites A, 2005(36), p1188-1206
R.H.W. ten Thije, R. Loendersloot, and R. Akkerman, Material characterisation for finite element simulations of draping with non-crimp fabrics, 6th ESAFORM conference, Salerno (Italy), 2003, p859-862
R. Loendersloot, R.H.W. ten Thije, R. Akkerman, S.V. Lomov, Permeability Prediction of Non-Crimp Fabrics Based on a Geometric Model, Proceedings of ECCM-11 Conference, Rhodos, Greece, CD-Edition, 2004
R.H.W. ten Thije, R. Loendersloot, and R. Akkerman, Material characterisation for finite element simulations of draping with non-crimp fabric, 6th ESAFORM conference, Salerno (Italy), 2003, p859-862
R. Loendersloot, R.H.W. ten Thije, S.V. Lomov, R. Akkerman and I. Verpoest, Geometry, Compressibility and Porosity of Sheared Non-Crimp Fabrics, Proceedings of SiComp Conference, Piteå, 2003, CD-edition
R.H.W. ten Thije, R. Akkerman, Finite element simulation of draping with non-crimp fabrics, Engineering Mechanics Symposium, Rolduc, 2004.
R.H.W. ten Thije, R. Loendersloot, R. Akkerman, Finite element simulation of draping with non-crimp fabrics, Engineering Mechanics Symposium, Rolduc, 2003