Development of simulation models for additive manufacturing semi-crystalline polymers

• Main Author: Antony Samy, Anto
• Format: Dissertation
• Language: English
• Published: Ulster University 2023
• Subjects: Finite element analysis (FEA); Fused deposition modelling (FDM); Polymer crystallisation kinetics; Residual stress; Semi-crystalline polymers; Warpage

Fused Deposition Modelling (FDM) is one of the Additive Manufacturing (AM) techniques that has been gaining traction due to its ability to print complex 3D shaped geometries and simplicity in manufacturing of the part. Despite its advantages, among thermoplastics polymers, amorphous polymers are predominantly used as feedstocks due to the challenges faced with semi-crystalline polymers. Due to the crystallisation kinetics in semi-crystalline polymers are highly temperature dependant and can be influenced by the FDM processing parameters, semi-crystalline polymers are challenging to print via FDM process. This study focuses on developing a simulation model to investigate the effect of process parameters on crystallisation and resulting part distortion in semi-crystalline polymer parts. Although studies have been performed in the past, there is a lack of simulation models available in the literature that can predict part distortion with respect to various FDM processing parameters in semi-crystalline polymers by taking crystallisation kinetics into account. In this thesis, processing parameters such as ambient temperature, print bed temperature, nozzle speed, raster pattern, layer thickness, overall height of the model/sample, and FEA boundary condition assumption of layer bonding are investigated. The warpage results predicted by the novel simulation model developed using the modified crystallisation physics in this study has displayed an overall accuracy of 82% on validating with the experimental warpage data.