Measurement and Modelling of Thermal and Mechanical Anisotropy of Parts Additively Manufactured using Fused Deposition Modelling (FDM)

Fused deposition modelling (FDM) is an additive manufacturing (AM) technique which involves melting a thermoplastic filament material and subsequently extruding it, layer by layer, to create three-dimensional objects. The nature of this build process yields parts with inhomogeneous compositions, which may result in anisotropic thermal and mechanical properties. In this work, such anisotropies were investigated for different commercially-available FDM materials such as polylactic acid, acrylonitrile butadiene styrene, and polyurethane. Due to the biaxial symmetry of some properties of resulting FDM parts, a transversely isotropic material model was developed for simulating the FDM part response to thermal and mechanical loads. Such a model is more robust than an isotropic model and, when compared to a full orthotropic model, requires fewer elastic constants to be experimentally determined. Ultimately, the development of FDM-specific thermomechanical property data and models for AM parts will provide more accurate parameters for part designs, leading to higher confidence in part qualification.