Numerical simulation and optimisation of a composite curing process of prepreg with infrared heating
Topic(s) : Manufacturing
Co-authors :
Lucas SARDO (FRANCE), Sacha EL AOUAD , Giulia LISSONI , Laurent RATTEAbstract :
The production of prepreg composites by hot molding in an autoclave requires long heating cycles of several hours (à verifier) [ref] to allow the resin to polymerize, making this process expensive. Therefore, a new non-autoclave process has been developed [ref]: this new process involves placing the part in an oven. A good understanding of the role of heat in the oven on the curing of the parts (or cross-linking of the resin) is essential to guarantee parts with the desired mechanical properties and also to optimize the duration of the heating cycles.
To achieve this, 3D simulation of the process could be a powerful tool for studying the influence of heat on the cross-linking properties of the resin. This alternative to experiments allows to study the behavior in a more cost-effective and environmentally friendly way, while guaranteeing results that are close to experimental measurements.
In this study, the part is made from prepregs that are applied to a rigid mold and compacted between the mold and a vacuum bag. The prepreg is then cured (out of autoclave) in an oven heated by infrared radiation. The main advantage of this approach is that the part can be heated directly by radiation, resulting in a more uniform temperature across the surface of the part, without the thermal inertia of more conventional electrical resistors. This results in better mechanical properties and faster cure times.
For the computation, only one monolithic domain is considered including the oven, the air, the mold and the prepreg. The radiation is taken into account using the surface-to-surface (S2S) method, the kinetics in the part are modelled using a Kamal-Sourrour equation, and the thermal equations are solved taking into account the radiation fluxes, the thermophysical properties of the different medias, a tensor conductivity for the prepreg and a contact thermal resistance between the part and the mold. The transparent tarpaulin used to evacuate the resin is considered negligible to the radiation that heats the surface of the resin directly.
Simulation provides 2D/3D maps of radiation fluxes, temperature fieds in the mold and part as well as curing history over time and at any point on the part. This allows to understand the thermal history of the part and subsequently optimize oven heating to reduce temperature gradients and cure differences as the part heats in the oven, resulting in better mechanical properties of the final part. In this way, qobeo® enables digital accurate process analysis and savings in time, energy, material and investment.
To achieve this, 3D simulation of the process could be a powerful tool for studying the influence of heat on the cross-linking properties of the resin. This alternative to experiments allows to study the behavior in a more cost-effective and environmentally friendly way, while guaranteeing results that are close to experimental measurements.
In this study, the part is made from prepregs that are applied to a rigid mold and compacted between the mold and a vacuum bag. The prepreg is then cured (out of autoclave) in an oven heated by infrared radiation. The main advantage of this approach is that the part can be heated directly by radiation, resulting in a more uniform temperature across the surface of the part, without the thermal inertia of more conventional electrical resistors. This results in better mechanical properties and faster cure times.
For the computation, only one monolithic domain is considered including the oven, the air, the mold and the prepreg. The radiation is taken into account using the surface-to-surface (S2S) method, the kinetics in the part are modelled using a Kamal-Sourrour equation, and the thermal equations are solved taking into account the radiation fluxes, the thermophysical properties of the different medias, a tensor conductivity for the prepreg and a contact thermal resistance between the part and the mold. The transparent tarpaulin used to evacuate the resin is considered negligible to the radiation that heats the surface of the resin directly.
Simulation provides 2D/3D maps of radiation fluxes, temperature fieds in the mold and part as well as curing history over time and at any point on the part. This allows to understand the thermal history of the part and subsequently optimize oven heating to reduce temperature gradients and cure differences as the part heats in the oven, resulting in better mechanical properties of the final part. In this way, qobeo® enables digital accurate process analysis and savings in time, energy, material and investment.