DYNAMIC MECHANICAL PROPERTIS OF WOVEN CARBON FIBRE REINFORCED THERMOPLASTIC COMPOSITE MATERIALS

The aim of this research is to investigate the dynamic mechanical properties of woven carbon fibre reinforced poly ether ether ketone (PEEK) using both experimental and numerical methods. Studies are carried out over a range of temperatures and dynamic strain rates. A numerical model is developed to predict the response of the composite under mechanical loading. The finite element method is employed to develop a suitable three-dimensional representative volume element (RVE) to predict the Young's modulus and the effective loss factor for the woven composite material. The model allows slip between the bundles of carbon fibre and the polymer; hence the effects of bond strength are studied. The results show that the stiffness increases with friction gradually, and the loss factor increases up to a value of 0.5 for the coefficient of friction. The polymer is modelled considering hyperelastic and viscoelastic behaviour which allows the analyses to be carried out near the glass transition temperature. Experimental dynamic mechanical analysis carried out on the composite specimens show that the Young's modulus decreases and the loss factor increases with increasing amplitude. At higher temperatures, an increase in the loss factor, a decrease in the stiffness and greater ductility are observed. From flexural tests, an increase in ductility, reduction in modulus and higher resistance to failure are noted with increasing temperature from 25 degrees C to 150 degrees C. The comparisons between numerical and experimental results show similar trends for the modulus and loss factor with temperature.