Modelling FSI test cases using a CEL approach in the context of overmoulding fibre skeleton structures

Overmoulding of three-dimensional continuous fibre skeletons is an advanced manufacturing process for producing high-performance structural components with exceptional mechanical properties and design flexibility. The process enables components to be adapted to specific load conditions and facilitates the creation of high-performance lightweight structures with novel geometries.Despite significant advancements in process technologies [1]-[2], the material behaviour and interaction mechanisms during overmoulding are not yet fully understood. To address this gap, numerical process simulation is used to deepen understanding of the process and create a basis for virtual process design and reliable prediction of component properties.

Since the polymer melt flow interacts with the deformation of the fibre skeletons during overmoulding, the fluid phase is modelled with a Coupled Eulerian-Lagrangian (CEL) formulation in Abaqus/Explicit. In CEL, the phase is deformed in a Lagrangian step for each time step and then projected back to an Eulerian mesh, accounting for the transport equations [4]. This framework is well suited to problems involving large deformations and fluid motion simultaneously, and has been successfully used for the simulation of fibre bundles in compression moulding processes [5].
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In the present work, a fluid-structure interaction (FSI) between a polymer melt modelled as fluid phase in CEL and a solid fibre part modelled as Lagrangian body is investigated. In the literature, FSI test cases often exist only for Re ≫ 1 [6]. To verify the suitability of the CEL approach in the context of overmoulding, where Re ≪ 1 applies, two test cases are examined. In the first case, the fluid flow impacts the structure primarily perpendicularly, resulting in a deformation of the structure due to bending. The deformation of a circular clamped plate in a channel filled with fluid is compared to an analytical solution. In the second FSI case, the flow moves parallel to the structure, resulting in a deformation of the structure, that is dominated by shear.

The numerical results form the basis for a correct prediction of the interaction between fluid and fibre skeleton
during overmoulding and verify the suitability of the CEL approach in the context of overmoulding skeleton
structures.

References:
[1] B. Beck, H. Tawfik, J. Haas, Y.-B. Park, and F. Henning, “Automated 3D Skeleton Winding Process for Continuous-Fiber-Reinforcements in Structural Thermoplastic Components,” in Advances in Polymer Processing 2020, C. Hopmann and R. Dahlmann, Eds., Berlin, Heidelberg: Springer Berlin Heidelberg, 2020, pp. 150–161. doi: 10.1007/978-3-662-60809-8_13. [2] N. Minsch, M. Müller, T. Gereke, A. Nocke, and C. Cherif, “Novel fully automated 3D coreless filament winding technology,” Journal of Composite Materials, vol. 52, no. 22, pp. 3001–3013, Sept. 2018, doi: 10.1177/0021998318759743.
[3] J. Haas, “Load-compliant dimensioning of coreless-wound fiber skeletons for the local reinforcement of structural polymer parts,” Doctoral thesis, Karlsruhe Institute of Technology (KIT), 2024.
[4] D. J. Benson, “Computational methods in Lagrangian and Eulerian hydrocodes,” Computer Methods in
Applied Mechanics and Engineering, vol. 99, no. 2–3, pp. 235–394, Sept. 1992, doi: 10.1016/0045-7825(92)90042-I.
[5] N. Meyer, S. Ilinzeer, A. N. Hrymak, F. Henning, and L. Kärger, “Non-isothermal direct bundle simulation of SMC compression molding with a non-Newtonian compressible matrix,” Journal of Non-Newtonian Fluid Mechanics, vol. 310, no. 104940, Dec. 2022, doi: 10.1016/j.jnnfm.2022.104940.
[6] E. Bayraktar, O. Mierka, and S. Turek, “Benchmark computations of 3D laminar flow around a cylinder with CFX, OpenFOAM and FeatFlow,” IJCSE, vol. 7, no. 3, p. 253, 2012, doi: 10.1504/IJCSE.2012.048245