Investigating thermal strains and chemical shrinkage in tomographic volumetric additive manufacturing

Volumetric additive manufacturing provides many advantages over more traditional layer-based additive manufacturing methods by permitting support-free printing with isotropic material properties. However, accurate geometry reproduction remains a challenge. This work presents two models to investigate the contributions of thermal strains and chemical shrinkage to parts made via tomographic volumetric additive manufacturing. A thermal model, with invariant material properties and uniform cure progression, reproduces similar magnitude deformations to those seen experimentally. Through a parameter study and partial least squares regression, for a target cube geometry, deformations are found to be dominated by the heat transfer coefficient. A second model investigates non-uniform chemical shrinkage predicting smaller deformations but better capturing the deformed shape. This work concludes that a combination of primarily thermal strains and secondarily chemical shrinkage is thus required to capture this geometric infidelity paving the way to better understanding the deformation phenomena.