Colloquia

Summary

The application of thermoplastic composite materials are of great interest for automotive and aerospace industries for their high stiffness relative to their weight. Furthermore, they can be easily molded, shaped, formed, re-heated and reformed during manufacturing and therefore have potential for faster production rates and recyclability. To realize this potential the deformation and flow behavior needs to be investigated. Experimental research was conducted to develop a new method to characterize the transverse flow behavior of unidirectional (UD) thermoplastic composites. In this research, the materials LMPAEK and carbon fiber LMPAEK composite (C/LMPAEK) were brought to above melting temperature in a rheometer and were subjected to indentation tests at different constant indentation velocities. The LMPAEK material was indented with an axisymmetric spherical indenter and the measured normal forces over indentation depth were compared to conventional viscosity test methods, a closed form solution, and finite element method simulations. The C/LMPAEK material was indented with a cylindrical indenter in the fiber direction to isolate the transverse flow behavior from the longitudinal flow behavior. A plane strain Kelvin model simulation was fitted to the measured indentation force over indentation depth to see if it was possible to find an approximation of the transverse viscosity of C/LMPAEK in melt. From this research, the start of a new method to characterize transverse flow behavior in UD thermoplastic composites was realized, although further research on the topic is needed to fully understand the material behavior in these specific conditions.