Modelling the influence of infrared preheating and temperature uniformity in forming of powder-impregnated thermoplastic composites

Non-isothermal thermoforming of thermoplastic composites, in which a preconsolidated blank is heated above the melting temperature of the matrix before being formed in a press, is a process well adapted to the high production rates of automotive structural parts, allowing for cycle times <br>This thesis focused on the development of a comprehensive simulation of the forming of powder-impregnated PA66/glass composites, modelling explicitly the infrared preheating step to investigate the effect of temperature homogeneity on shape defects.

The thermophysical and optical properties of the material were characterized experimentally at two levels of consolidation, and as a function of temperature when relevant. The structure of the non-consolidated material leads to a less uniform heating, compared to preconsolidated blanks. A finite element model based on the radiosity method to compute the radiative heat transfer was used to simulate the preheating step; this approach was validated against experimental results from a custom-built infrared oven.