Open Access

Nils Meyer, Stefan Panzer

• Injection molding and compression molding are cost-effective processes for manufacturing discontinuous fiber reinforced polymer composite parts with complex geometries. The resulting properties of such parts depend on local fiber orientations, and we propose a novel approach to determine the orientation field as solution to an inverse problem: Given the deformation field of a part measured via digital image correlation (DIC), we determine the local orientations leading to that deformation. We model the structural deformation of the part with a differentiable finite element solver and mean field homogenization. Subsequently, we compute the error to the DIC measurement and minimize that error with respect to the input orientations. The gradients for optimization of the finite element model are computed efficiently using automatic differentiation with PyTorch through the entire model. The method is validated and discussed for carbon fiber sheet molding compounds under tensile loading butInjection molding and compression molding are cost-effective processes for manufacturing discontinuous fiber reinforced polymer composite parts with complex geometries. The resulting properties of such parts depend on local fiber orientations, and we propose a novel approach to determine the orientation field as solution to an inverse problem: Given the deformation field of a part measured via digital image correlation (DIC), we determine the local orientations leading to that deformation. We model the structural deformation of the part with a differentiable finite element solver and mean field homogenization. Subsequently, we compute the error to the DIC measurement and minimize that error with respect to the input orientations. The gradients for optimization of the finite element model are computed efficiently using automatic differentiation with PyTorch through the entire model. The method is validated and discussed for carbon fiber sheet molding compounds under tensile loading but can be extended to arbitrary parts with defined load cases and available DIC data.…