Temperature Effects on the Mechanical Behaviour of PAEK Thermoplastic Composites Subjected to High Strain Rates Under Compression Loading

Resumo

© 2020 Elsevier LtdThis work presents an experimental study on the mechanical behaviour of thermoplastic polyarlyetherketone (PAEK) based composite laminates reinforced with woven carbon fibres, subjected to high strain rates under compression loading. The specimens were tested using a Split Hopkinson Pressure Bar (SHPB). The tests covered the working temperatures and stress envelopes of −54 °C, RT (25 °C), and 80 °C, each tested at six different off-axis angles. The high-speed imaging system was used to monitor the failure process. The strain on the loading direction was determined using Digital Image Correlation (DIC). Fractography analysis was performed to understand the influence of temperature on the damage aspects, using Scanning Electron Microscopy (SEM). The −54 °C and RT SHPB tests showed more intralaminar damage aspects than the ones tested at 80 °C, which presented a preference for the interlaminar damage aspect and exhibited the lowest strength. A new failure criterion dependent on temperature and strain rate was proposed, based on a phenomenological approach and experimental results. The fabric architecture at the ply level was idealised as a two-part mosaic model. The crystallinity of the PAEK thermoplastic matrix was analysed using Differential Scanning Calorimetry (DSC). Results showed no evidence of crystallinity degree variation induced by the high strain rate tests.

Palavras-chave