The Impact of Draping Effects on the Stiffness and Failure Behavior of Unidirectional Non-Crimp Fabric Fiber Reinforced Composites

Materials

Robert Böhm¹  Maik Gude¹  Eckart Kunze¹  Luise Kärger²  Siegfried Galkin² 

[1] Institute of Lightweight Engineering and Polymer Technology, Technical University Dresden, Holbeinstrasse 3, D-01307 Dresden, Germany;Karlsruhe Institute of Technology (KIT), Institute of Vehicle System Technology (FAST), Lightweight Technology (LBT), Rintheimer Querallee 2, D-76131 Karlsruhe, Germany;

关键词: unidirectional non-crimp fabrics;    draping effects;    deformation modes;    mechanical properties;    fiber volume content;    waviness;   

DOI  :  10.3390/ma13132959

来源: DOAJ

【 摘 要 】

Unidirectional non-crimp fabrics (UD-NCF) are often used to exploit the lightweight potential of continuous fiber reinforced plastics (CoFRP). During the draping process, the UD-NCF fabric can undergo large deformations that alter the local fiber orientation, the local fiber volume content (FVC) and create local fiber waviness. Especially the FVC is affected and has a large impact on the mechanical properties. This impact, resulting from different deformation modes during draping, is in general not considered in composite design processes. To analyze the impact of different draping effects on the mechanical properties and the failure behavior of UD-NCF composites, experimental results of reference laminates are compared to the results of laminates with specifically induced draping effects, such as non-constant FVC and fiber waviness. Furthermore, an analytical model to predict the failure strengths of UD laminates with in-plane waviness is introduced. The resulting stiffness and strength values for different FVC or amplitude to wavelength configurations are presented and discussed. In addition, failure envelopes based on the PUCKmathsizesmall failure criterion for each draping effect are derived, which show a clear specific impact on the mechanical properties. The findings suggest that each draping effect leads to a “new fabric” type. Additionally, analytical models are introduced and the experimental results are compared to the predictions. Results indicate that the models provide reliable predictions for each draping effect. Recommendations regarding necessary tests to consider each draping effect are presented. As a further prospect the resulting stiffness and strength values for each draping effect can be used for a more accurate prediction of the structural performance of CoFRP parts.

【 授权许可】

Unknown