Predictieve digitale tweeling voor niet-lineaire vervorming bij het thermoformen van ABS-materiaal

In vacuum forming, thermoplastic polymeric sheets are molded into complex 3D shapes by first heating the sheet above its glass transition temperature to soften the material and then shaping it by applying vacuum. The quality of a vacuum-formed part relates strongly to the final wall thickness distribution. The variations in the wall thickness are caused by non-uniform heating and local differences in thermomechanical properties of the polymer sheet. In this project, experimental methods to capture both the forming behaviour of the sheet as well as the relevant material properties are designed and implemented. Subsequently, making the link between the experimental characterization tests and the constitutive equations leads to having a robust and reliable foundation for numerical simulation of the vacuum forming process. This simulation includes different steps: gravitational sagging, IR heating, pre-blowing, forming, cooling, and trimming. By taking all thermomechanical effects that take place during processing into account, the residual stress build-up in the final part can be analysed and used to predict the final part shrinkage and warpage. The overall goal of the simulation tool-chain aims at predicting and optimizing the final wall thickness distribution as well as final part geometry and size with respect to the applied vacuum forming tool and process.