A finite element simulation model of convective heat-assisted single-point incremental forming of thermoplastics

The objective of this research is to simulate the effects of temperature on the stress, strain, and forming forces in the single-point incremental forming process of polymers through the development of a FEA model. Currently available SPIF simulation models are limited to room temperature and are not suited to processes that use localized heating to increase formability. The model developed in this research consists of three key components: (a) simulated temperature spot using a distribution of convective heat transfer coefficients (HTC) values, (b) temperature-dependent material behavior using the Three Network model (TNM), and (c) and the integration of thermal and mechanical behavior of the SPIF process. The forming of a polycarbonate cone with a constant wall angle of 45 degrees is simulated using the model under two conditions: (i) room temperature SPIF and (ii) CHASPIF using an external hot air source of 250 degrees F (121.11 degrees C). The accuracy of the predicted deformation and temperatures varies in the different zones. Inside the formed wall, the temperature distribution is predicted within +/- 5 degrees C for CHASPIF, and deformation within 0.766 mm for CHASPIF and 0.786 mm for SPIF compared to experimental results. Future research will be focused on improving the accuracy of the model and evaluating process limits for more complex shapes. The simulation model is ultimately intended to be used for model-based manufacturing.