Process modeling and deformation prediction of 3D printed continuous fiber-reinforced composites based on in-situ micro-scale measuring

3D printing of continuous fiber-reinforced thermoplastic composites (CFRTPCs) is a promising manufacturing technology. However, deformation caused by the release of residual stresses in printed parts remains unavoidable, and there is a lack of accurate and comprehensive measurements or models addressing the microscopic factors behind their formation. This paper presents in-situ measurements of process parameters related to residual stress formation, including temperature gradients, printing force fields, and deformation of printed samples. As temperature is a key factor contributing to residual stresses, this study introduces an in-situ micro-scale characterization method for the printing temperature field using temperature-sensitive prepreg filaments. The method enables accurate measurement of the full life cycle temperature data across different microscopic regions of the prepreg filament during printing. Using the measured data, including temperature, printing pressure, and tension force, this paper proposes a multi-scale process modeling method referred to as the “extrusion process-printing process combination”. This model simulates the temperature field distribution during the extrusion process, as well as the residual stress and deformation during the printing process. Simulation results were validated by experiments, with an error margin of less than 5 %. Using this model, the preliminary process optimization for reducing the residual stress was carried out. In addition, the effects of various process parameters on the temperature gradient during printing and the deformation of printed samples were analyzed. The results show that by optimizing the printing process, it is expected to reduce the generation of residual stresses in composite printed products.