@article{DriesWallmerspergerKessler2022, author = {Dries, Fabian W. and Wallmersperger, Thomas and Kessler, J{\"o}rg}, title = {Deformation of planar ring mesh under static in-plane tensile loads}, volume = {234}, journal = {Acta Mechanica}, number = {3}, publisher = {Springer-Verlag GmbH Austria}, address = {Wien}, issn = {1619-6937}, doi = {https://doi.org/10.1007/s00707-022-03393-2}, pages = {959 -- 973}, year = {2022}, abstract = {A ring mesh is a large-scale manufacturable structure with versatile applications in architecture and for protective systems. However, the static and dynamic numerical simulation of a large-scale ring mesh is a resource-intensive task due to the many nonlinear contact points between the individual rings. To characterize the rigid body behavior of the ring mesh, in this paper, a representative volume element is loaded under different in-plane directions. The Green-Lagrangian strain tensor components are obtained as a result. An implicit one-step algorithm is used for this dynamic relaxation issue, modified by the use of stiff springs. Static convergence positions of a representative volume element are determined in several multiaxial tensile directions. The obtained deformation parameters can be used to simulate large deformations of large-scaled ring meshes.}, language = {en} } @article{HandwerkerKesslerMarzbanietal.2022, author = {Handwerker, Michael and Kessler, J{\"o}rg and Marzbani, Hormoz and Tetzlaff, Ulrich}, title = {Pressure and heat treatment of continuous fibre reinforced thermoplastics produced by fused filament fabrication}, volume = {8}, journal = {Progress in Additive Manufacturing}, number = {2}, publisher = {Springer}, address = {Cham}, issn = {2363-9520}, doi = {https://doi.org/10.1007/s40964-022-00315-5}, pages = {99 -- 116}, year = {2022}, abstract = {Fused filament fabrication allows for the additive manufacturing of complex geometries without requiring moulds. However, due to large air voids and poor layer adhesion, the mechanical properties of parts manufactured using fused filament fabrication lag behind those of parts manufactured using conventional techniques. A previous study found that the tensile strength and Young's modulus of such parts could be increased by a heat-treatment process. However, large air voids were still present after annealing. This study, therefore, investigates the influence of a post-pressure-treatment process on the mechanical performance and the air void ratio of continuous glass fibre-reinforced polyamide 6 in the directions perpendicular to the fibres. Without the treatment, Young's modulus on the plane parallel to the printing bed is eight times higher than Young's modulus perpendicular to it. Annealing at 1 MPa homogenises the material and leads to a significant increase of both the tensile strength (55 MPa) and Young's modulus (5 GPa). Increasing the pressure to 3 MPa only slightly increases the mechanical performance, whereas a further increase to 6 MPa causes no significant changes.}, language = {en} }