Homogenisation of elastic properties in FDM components using microscale RVE numerical analysis

Fused deposition modelling (FDM) is an additive manufacturing method having the potential to fabricate functional components. As the inherent nature of additive structures, the component stiffness depends on the build parameters such as layer height and raster orientation in addition to the filament material properties. Even on FDM prints with 100% infill density, voids are formed along the interface of rasters and contribute to the characteristics of the component. The primary role of the present work is to determine elastic characteristics such as Young’s modulus, shear modulus and Poisson’s ratio of FDM components and study the effect of build parameters. The void geometry identified from the cross-sectional morphology was used to create a microscale representative volume element (RVE) model capturing the characteristics of the FDM print. The elastic constants of the microscale model RVE were estimated by volume average method and homogenised over the entire structure. The study also investigated the influence of layer height on the elastic behaviour of FDM components in two different raster orientations of 0° and 0°/90°. Both the conditions exhibited directional characteristics and the elasticity constants approaches filament characteristics with decreases in the layer height. The modulus of elasticity was found maximum in the direction of raster orientation, whereas the elasticity modulus along vertical direction exhibited the lowest. The components with 0°–90° raster orientation exhibited transversely isotropic characteristics. Thus, the actual cross-sectional morphology-based microscale numerical analysis can effectively predict the directional attributes of FDM prints.