From images to material characterization of additively manufactured micro-architectured structures

Recent developments in additive manufacturing have provided a unique possibility to create complex structures with porosity on a micro and meso-structural levels. Such designs can outperform conventional materials in specific industrial applications, e.g. turbine blades with a transpiration cooling. However, the high flexibility of the input parameters for the 3D printers, such as the laser diameter, hatch distance etc., challenges a reliable estimation of the mechanical behaviour of the final parts. Moreover, a high variation of porosity in all of the material directions limits the application of analytical bounds based on the void fraction ratio. Numerical homogenization is an efficient and robust alternative to perform non-desctructive evaluation of the material characteristics based on high resolution 3D images of produced specimens. The conventional Finite Element Method applied to numerical homogenization leads to a labor intensive meshing procedure to extract the representative volume elements that makes it impractial from the industrial point of view. Furthermore, non-symmetric micro-architectured structures make it difficult to apply correct boundary conditions for the solution of the microstructural boundary value problem. To address these issues, in the scope of the presented work the Finite Cell Method is employed in combination with the window method. A road map is presented for the automatized numerical computation of the homogenized elasticity tensor of additively manufactured steel structures using 3D images. The computational results are verified with the direct finite-cell computation of a given produced specimen. Validation of the proposed model is performed comparing the numerical results with the results stemming from experimental tests.     «

Recent developments in additive manufacturing have provided a unique possibility to create complex structures with porosity on a micro and meso-structural levels. Such designs can outperform conventional materials in specific industrial applications, e.g. turbine blades with a transpiration cooling. However, the high flexibility of the input parameters for the 3D printers, such as the laser diameter, hatch distance etc., challenges a reliable estimation of the mechanical behaviour of the final p...     »