Optimisation of the Laser-Assisted Tape Placement Process
Start / End:
June 2007 to June 2012
This project is part of the ECO-Design ITD within the European Clean Sky project. The use of the tape placement equipment was kindly facilitated by AFPT Advanced Fiber Placement Technology, while Ten Cate Advanced Composites supplied the fibre reinforced tape material.
Laser-assisted tape placement is an attractive manufacturing technology for the aerospace industry as it combines high productivity with low energy consumption. It comprises the automated deposition of fiber reinforced thermoplastic tapes to incrementally build up a structure. The process can also be used to tailor the properties of conventionally manufactured woven fabric reinforced components by locally reinforcing these with unidirectionally reinforced tapes. This thesis focuses on the weld strength between the tape and the woven fabric reinforced component. The principal objective is to develop an in situ processing strategy, combining high productivity and energy efﬁciency with high weld strength. For this purpose, the important bonding mechanisms, processing parameters and material properties are identiﬁed through a combination of experimental work and physical modeling.
The interlaminar bonding process comprises the development of intimate contact followed by the interdiffusion of polymer chains. Both mechanisms depend strongly on the interface temperature. A thermal process model is, therefore, proposed speciﬁcally taking into account the optical aspects of laser heating. The model is validated experimentally. Based on the developed model, the important processing paramaters and material properties are identiﬁed. A mandrel peel test is introduced to quantify the interfacial fracture toughness between the tape and the laminate. The applicability and validity of the method is successfully demonstrated by comparing it to standardized fracture mechanics
tests. The interfacial fracture toughness does not only depend on the degree of interlaminar bonding. The crystallinity and structural morphology of the interface also play an important role. This is demonstrated by a comparison between the (fast) tape placement process and a (slow) press-molding process. The tape-placed specimens outperform the press-molded specimens in terms of fracture toughness by almost a factor of two. This is attributed to the high cooling rates and short bonding time during the tape placement process. The former results in a low crystallinity,
while the latter prevents the migration of tape fibers into the resin pockets of the laminate and thereby minimizes the fiber–fiber contact. Both the low crystallinity and the presence of resin pockets improve the interfacial fracture toughness.
Finally, a processing strategy is proposed, which maximizes productivity and energy efﬁciency. The strategy involves the distribution of all laser power to the tape. Although the proposed strategy should be tested in practice, the work in this thesis suggests that an excellent weld strength will be achieved.
W.J.B. Grouve, Weld strength of laser-assisted tape-placed thermoplastic composites, PhD thesis University of Twente, 2012, ISBN 978-90-365-3392-8.
Grouve, W.J.B. and Warnet, L.L. and Akkerman, R. (2012) Critical assessment of the mandrel peel test for fiber reinforced thermoplastic laminates. Engineering Fracture Mechanics.
Grouve, W.J.B. and Warnet, L.L. and Rietman B. and Akkerman, R. (2012) On the weld strength of in situ tape placed reinforcements on weave reinforced structures. Composites Part A, 43 (9). pp1539-1536.
Grouve, W.J.B. and Akkerman, R. (2010) Consolidation process model for film stacking glass/PPS laminates. Plastics, Rubber and Composites, 39 (3-5). pp. 208-215. ISSN 1465-8011
Grouve, W.J.B. and Warnet, L. and Akkerman, R. and Wijskamp, S. and Kok, J.S.M. (2010) Weld Strength Assessment for Tape Placement. International Journal of Material Forming, 3 (Suppl.). pp. 707-710. ISSN 1960-6206
Grouve, W.J.B. and Akkerman, R. (2009) Multi-scale effects in the consolidation of thermoplastic laminates. International Journal of Material Forming, 2 (Suppl.). pp. 157-160. ISSN 1960-6206
Grouve, W.J.B. and Akkerman, R. and Loendersloot, R. and Berg van den, S. (2008) Multi-scale effects in the consolidation of thermoplastic laminates. International Journal of Material Forming, 1 (Suppl.). pp. 859-862. ISSN 1960-6206
Grouve, W.J.B. and Warnet, L. and Boer de, A. and Akkerman, R. and Vlekken, J. (2008) Delamination detection with fibre Bragg gratings based on dynamic behaviour. Composites Science and Technology, 68 (12). pp. 2418-2424. ISSN 0266-3538
Loendersloot, Richard and Grouve, Wouter and Lamers, Edwin and Wijskamp, Sebastiaan (2012) Textile impregnation with thermoplastic resin - models and application. In: 11th International Conference on Flow Processing in Composite Materials, 9-12 July 2012, Auckland, NZ.
Grouve, W.J.B. and Warnet, L.L. and Akkerman, R. (2010) Towards a process simulation tool for the laseer assisted tape placement process. In: 14th European Conference on Composite Materials, ECCM 2010, June 7-10, 2010, Budapest, Hungary.
Loendersloot, Richard and Grouve, Wouter J.B. and Akkerman, Remko and Boer de, André (2010) Development of a multigrid finite difference solver for benchmark permeability analysis. In: 10th International Conference on Flow Processes in Composite Materials, FPCM 2010, July 11-15, 2010, Ascona, Switserland.
Grouve, W.J.B. and Akkerman, R. (2009) A consolidation process model for film stacking glass/PPS laminates. In: 17th International Conference on Composite Materials, ICCM 2009, 27-31 July 2009, Edinburgh, UK
Grouve, W.J.B. and Akkerman, R. and Loendersloot, R. and Berg van den, S. (2008) Transverse permeability of woven fabrics. In: 11th ESAFORM Conference on Material Forming 2008, April 23-25, 2008, Lyon, France
Grouve, Wouter J.B. and Akkerman, Remko (2008) An idealised BC for the meso scale analysis of textile impregnation. In: 9th International Conference on Flow Processes in Composite Materials, FPCM 2008, 8-10 July 2008, Montreal, Canada.
Loendersloot, R. and Grouve, W.J.B. and Akkerman, R. and Berg van den, S. (2008) Permeability prediction using a multigrid method. In: 9th International Conference on Flow Processes in Composite Materials, FPCM-9 2008, 8-10 July 2008, Montreal, Canada.
Wouter Grouve is since 2012 linked to TPRC, the Thermoplastic composite Research Centre, Enschede, The Netherlands.