Residual Strain Monitoring During Hot Pressing of Thermoplastic Composites by a Distributed Fiber
N. Saito, H. Horizono, N. Ishikawa, T. Takayanagi
Mitsubishi Heavy Industries, LTD, Nagoya-shi, Japan
N. Takeda, The University of Tokyo, Chiba-ken, Japan
H. Kojima, SOKEIZAI Center, Tokyo, Japan
This paper investigates the relationship between consolidation processes and mechanical properties of carbon fibre reinforced thermoplastics (CFRTPs) by monitoring residual strain during the processes. In order to monitor the solidification behaviours during the process, the authors use a distributed fibre optic sensing technology, the Brillouin optical correlation domain analysis (BOCDA). In this study, a fibre optic sensor (FOS) was embedded into a quasi-isotropic carbon fibre (CF) / polyetheretherketone (PEEK) laminates. This CFRTP was fabricated by hot pressing with three cooling speed. Strain changes during the process and residual strain after cooling were measured by the embedded FOS. Temperature was monitored by a thermocouple which was embedded in the molding tool for compensating temperature effects of the FOS. Firstly, as for the cooling speed, residual strain value was lower as the cooling speed was faster. This is because the crystallinity of the materials affects the residual strain. To determine the relationship between crystallinity and the cooling speeds, differential scanning calorimetry (DSC) was carried out. From the DSC results, crystallinity of CFRTP laminates fabricated under faster cooling speed was lower than that under slower cooling speed. Secondly, there was no distinct differences on mechanical properties of the laminates that were fabricated under faster and slower cooling speed in this study. In summary, the authors show the feasibility of CFRTP process monitoring technique by using a distributed fiber optic sensing system to understand the internal strain behaviour during the process. This will contribute largely to set an optimum process for each consolidated products.
ITHEC 2016 Manuscript P10
Publication date: 01/10/2016
Manuscript P10 published in Conference Proceedings ITHEC 2016
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