Radiative Thermal Effects in Large Scale Additive Manufacturing of Polymers: Numerical and Experimental Investigations

The present paper addresses experimental and numerical investigations of a Large Scale Additive Manufacturing (LSAM) process using polymers. By producing large components without geometrical constraints quickly and economically, LSAM processes have the capability to revolutionize many industries. Accurate prediction and control of the thermal history is key for a successful manufacturing process and for achieving high quality and good mechanical properties of the manufactured part. During the LSAM process, the heat emitted by the nozzle leads to an increase in the temperature of the previously deposited layer, which prepares the surface for better adhesion of the new layer. It is therefore necessary to take into account this part of heat source in the transient heat transfer equation to correctly and completely describe the process and predict the temperature field of the manufactured part. The present study contributes to experimental investigations and numerical analysis during the LSAM process. During the process, two types of measurements are performed: firstly, the heat emitted by the nozzle is measured via a radiative heat sensor; secondly, the temperature field is measured using an infrared camera while varying the process speed. At the same time, a numerical simulation model is developed in order to validate the experimental results. The temperature fields of the manufactured parts computed by numerical simulations are in very good agreement with the temperature fields measured by infrared thermograph with the contribution of the nozzle’s heat exchange

Coupling inverse fin method with infrared thermography to determine the effective thermal conductivity of extruded thermoplastic foams

International audienceAn inverse method for determining the in-plane effective thermal conductivity of porous thermoplastics was implemented by coupling infrared thermography experiments and numerical simulation of heat transfer in straight fins having temperature-dependent convective heat transfer coefficient. The microstructure heterogeneity of extruded polyethylene foam, in which pores are filled with air with different levels of open and closed porosity, was taken into account. The obtained effective thermal conductivity values were compared with previous results obtained using a numerical solution based on periodic homogenization techniques (NSHT) and the transient plane source technique (TPS) to verify the accuracy of the proposed method. The results show that the suggested method is in good agreement with both NSHT and TPS. Moreover, it is also appropriate for structural materials such as unidirectional fiber-reinforced plastic composites, where heat transfer is very different according to the fiber direction (parallel or transverse to the fibers)