Anisotropic modeling of material behavior for additively manufactured parts made by material extrusion

Material extrusion is an additive manufacturing (AM) technique that provides an innovative and layer-by-layer fabrication method for components with intricate geometry. Due to the effect of various process parameters and the layerwise nature of material extrusion, the material behavior of parts made by this method is not isotropic. Considering the anisotropic material behavior of parts made by material extrusion, developing a finite element (FE) model to predict their mechanical properties is the focus of this study. Experiments including tensile tests, digital image correlation (DIC), and torsion tests were conducted to acquire the material constants for building an accurate FE model. Tensile behavior of specimens printed flat with different raster angles was investigated through a tensile test and modeled by FE software, Abaqus. DIC was used simultaneously with tensile tests to derive Poisson’s ratio; meanwhile, tensile tests’ results were analyzed to derive the elastic properties, such as modulus of elasticity, and plastic properties, such as tensile yield strength and plastic failure strain. In-plane, interlaminar, and out-of-plane shear properties of specimens were investigated through printing the samples with specific process parameters and running torsion tests. Hill anisotropic yield criterion and ductile damage criterion were also utilized in the FE model to define the plastic behavior of AM parts. The proposed FE model could predict the mechanical properties and fracture behavior of parts additively manufactured by material extrusion at any given unidirectional raster orientation. The accuracy of the proposed FE model was verified by the experiment results.