Transcrystalline interphase in fiber-matrix composites: Discovery and manufacturing impacts

Marc Schöneich, TU Dortmund, Dortmund, Germany
Markus Stommel, TU Dortmund, Dortmund, Germany

The present contribution is directed towards the realistic prediction of the mechanical material behaviour in the field of short glass fiber reinforced semi-crystalline thermoplastics. Therefore, the discovery of a transcrystalline interphase region between the fiber and the matrix is emphasized. This interphase is defined as the intersection region with modified bulk material properties. It is shown that nano-scratching provides a possible tool to determine the interphase thickness with adequate accuracy. However, no information about mechanical interphase behaviour is accessible with current measurements. Thus, an inverse approach is applied which combines the experimentally found interphase geometry and micromechanical modelling to obtain the interphases influences on the composites behaviour. Thus, it is shown that a realistic materials modelling and experimental investigations are closely interlinked.

Moreover, the displayed inverse technique is applied to study the impact of manufacturing on the interphase. Therefore, the injection molding production process of the composite samples is investigated with focus on the involved process parameters. Here, the investigations are concentrated on the possible influence on the fiber-matrix interphase as well as a stable process window. A screening of all eligible process parameters is performed and integrated into a parametric study. Thereby, the process parameters are optimized aiming at a dimensional accurate molded specimen geometry and a supposed high influence on the interphase.

In summary, the gain of information from the discovery to the manufacturing level can be used to increase the accuracy of FE simulations with an improved representation of fiber-matrix-interphase composites in materials modelling.

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