Effects of Defects on Mechanical Properties of Continuous Fiber Reinforced Laminates 


September 2016 - September 2020



Palatijn 15
7521 PN Enschede
P.O. Box 770
7500 AT Enschede
The Netherlands
Email: ramona.sitohang@tprc.nl

University of Twente
Faculty of Engineering Technology
Chair of Production Technology
P.0. Box 217
7500 AE Enschede
the Netherlands
Phone:+31 (0)53 489 3918
Email: r.d.r.sitohang@utwente.nl


This project is jointly funded by University of Twente and TPRC under the UT Impulse program.


Continuous fiber reinforced thermoplastics can be shaped in a press-forming step. Defects such as fiber wrinkling, voids, dry spots, ply squeeze-out or ply splitting or delamination may occur during the manufacturing process. Components with such defects are generally scrapped, as the influence of the defects on mechanical performance is unknown. Knowledge of the effect of defects on the mechanical performance potentially allows alleviation of the (often stringent) conformance rules. Therefore, with a proper understanding of the defects, reduction of the scrap rate may be achieved.


This project aims to improve the knowledge of the effects of defects that may occur during the press-forming manufacturing of thermoplastic composite parts on the mechanical properties of continuous fiber reinforced laminates through the combination of modeling and experimental work.

Current work

First step is to draft a comprehensive guide of defects by collecting the existing database of defects which frequently occur during the manufacturing of thermoplastic composite parts. Identification of the defects that should be prioritize in the investigation throughout the work can then be made based on the previous defects database. The next step is to develop experimental procedures for the reproduction and testing of representative specimens with predefined defects. This is carried out in order to generate mechanical properties of both the defected and (un-defected) specimens which correlate to defect severity parameters. A model will also be developed to describe effects of defects on mechanical performance for various loading conditions. The knowledge obtained from the combination of both experimental work and modeling approaches, will finally be used for the derivation of ‘knock-down’ factor for a set of defects.