Composites materials: numerical simulation of injection processes

The industrial group wished to investigate, via numerical simulation, the heat exchange and stages of material processing during the injection of sheet moulding compound (SMC) type composites. This material is made up of short fibres, impregnated with thermoset resin, that are shaped by the joint action of pressure and temperature in a heating mould.

This company entrusted the specialists at CAPACITÉS with characterizing the chemical shrinkage of the material (i.e., its contraction induced by the resin curing), and the influence of moulding pressure on this parameter.

These thermal phenomena were characterized by means of a specialized measuring apparatus: a PVT-α mould (Pressure-Volume –  Temperature – Degree of cure), which makes it possible to track the volume evolution of the composite sample as a function of pressure, temperature and degree of cure. Owing to this rare piece of equipment, CAPACITÉS’s experts were able to perform a complete analysis of the thermal phenomena in a single test. They were also able to identify the evolution of the thermal expansion coefficients in the raw and cured states of material, as well as the crosslinking enthalpy. The company will be using the results of this analysis to feed data into their simulation tools.

To complete this ambitious project, the CAPACITÉS’ experts benefited from support and technical equipment from the LTeN laboratory (Heat Transfer and Energy Laboratory), joint research unit of Nantes Université and the CNRS.