Thermo-elastomechanics with a liquid-solid phase transitionTurk, Janez (Avtor) Svenšek, Daniel (Mentor) Residual stressMolding defectsSink marksInjection moldingWarpagePlastic injection molding is a manufacturing process for producing complexly shaped plastic components, widely used in mass production industries. The process involves injecting molten polymeric material into a mold cavity, where it solidifies and takes the desired shape. During cooling, the solidified plastic continuously deforms due to thermal shrinkage, which can lead to warping of the final product or the appearance of surface defects, such as sink marks. Precise prediction of these deformations is essential for optimizing the injection molding process and ensuring the quality of the final product. In this study, we present a novel thermoelastic simulation method that predicts local deformation in injection molded parts by continuously calculating the displacement and stress fields of the solidifying plastic throughout the production process. Our approach accounts for the intricacies of part shape and enables the prediction of surface defects without requiring any specific material property measurement or calibration of the method. The method relies on material characterization data typically used in standard injection molding simulation analyses. The plastic injection molding process can be divided into three phases: the filling phase, the packing phase, and the cooling phase. Each of these phases has its pressure behavior regime in the liquid core of the product, which represents, along with the temperature change, an elastomechanical load for the plastic product. The pressure behavior in each of the phases is explained in this work, with a novel addition being a simple model of pressure behavior in the packing phase and the calculation of equilibrium pressure in the molten core during the cooling phase, which is crucial for predicting part deformation and ultimately for assessing the potential for void formation. We verified the accuracy of the thermoelastic method by comparing the results with measurements of products we injected using different process parameters. We also tested the method's performance with the result of a profilometry measurement published in the literature.20242024-01-20 08:15:05Doktorsko delo/naloga154030sl