Structure-mechanical property relationship in fused deposition modelling

The relationship between the filament scale phenomena and the macroscopic properties of parts manufactured by fused deposition modelling (FDM) of thermoplastic polymers has been investigated using planar geometry dog bone samples, representing layer by layer lamina in an additively manufactured part. Finite element simulations of the response of the FDM part(s) at multiple length scales (filament to macro) are compared with full field strain data obtained experimentally for different raster angles and filament gaps. The strain field, strain energy density, and effective Young's modulus are evaluated. Principal strains resulting from the applied axial loading shifted from the inner rasters to the contours of the FDM planar sample at certain raster angles as the air gap increased, which significantly decreased the effective usage of the material leading to strain localization and premature part failure. The research presented provides a pathway to an effective multiscale approach to optimise the raster contour fill pattern.