Construction of an isogeometric mechanical twin from tomographic images of lattice structures
Résumé
Today, the combination of Computer-Aided Design (CAD) and Additive Manufacturing (AM) offers the opportunity to create geometries of almost unlimited complexity. A striking example is lattice structures, which are architected structures providing exceptional mechanical properties (e.g., lightweight yet high mechanical stiffness) in a relatively straightforward manner. However, AM-induced defects are common in 3D-printed metallic lattices. Studies have shown that these defects can significantly affect the mechanical response of as-manufactured lattices compared to their as-designed counterparts. Investigating these defects requires a digital twin of the lattice, meaning a specimen-specific model that incorporates the actual geometry of the structure. The starting point for obtaining such a model is X-ray micro-Computed Tomography (µ-CT), a scanning method that provides 3D voxel-based images of the part's internal structure. In this work, a template-fitting method has been specifically developed for lattice structures. Using a virtual image correlation method, regularized by a thin membrane model, this approach allows for the construction of a multi-patch B-spline model to fit image data accurately, thereby capturing the geometric defects that occur during lattice fabrication. Then, a multi-patch B- spline volume mesh of the as-manufactured part is generated. Finally, this mesh is used to predict the behavior of the as-manufactured lattice structure with high accuracy and at a reduced computational cost by using isogeometric analysis.
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