Fiber laydown of Melt Spinning filaments - modeling, simulation, and experimental validation using bicomponent fibers

• Applicants: Dr. Andre Schmeißer; Professor Dr. Dirk W. Schubert
• Subject Area: Plastics Engineering
• Term: since 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 566051421

The melt spinning of synthetic fibers for the production of nonwovens is of growing importance in plastics processing, particularly for products such as filters, hygiene items, and respiratory masks. The current state of the art includes spunbond and meltblown processes as well as combined systems (e.g., SMS), whose efficiency and product quality are negatively impacted by the inhomogeneity of the nonwoven structures, known as cloudiness. Although these processes are industrially well established, the crucial aspect of fiber deposition, which determines the homogeneity of the nonwoven pattern, has been underexplored theoretically. This involves a complex interplay of stochastic and deterministic effects influenced by aerodynamics and mechanics, which is not yet sufficiently understood in scientific terms. The stochastic influence is fundamentally necessary for the process but must be controllable for product quality. The aim of the proposed project is to develop an experimentally validated simulation model that optimizes fiber deposition and improves the homogeneity of nonwoven materials. Specifically, using the spunbond process, the effects of turbulent air flow, fiber bending stiffness, and fiber-to-fiber interaction will be investigated, utilizing bicomponent fibers to vary bending stiffness without changing fiber diameter. This allows for the experimental separation of the mentioned effects for the first time. The methodology combines experimental approaches with simulations to replace or complement experiments with virtual test series. It is expected that this will enhance product quality and enable material savings of up to 15%, presenting significant economic potential. Long-term, the project aims not only to deepen process understanding but also to develop a new methodology for investigating various spinning processes and advance the modeling of interactions in turbulent air flow, leading to broader scientific insights and contributing to resource conservation through material savings. The modeling of fiber interactions in turbulent air flow is not process-specific and enables detailed simulations. The validated model will also serve as a foundation for more complex processes like meltblown, where the intended alignment of the applied air force models is not feasible as it is in this process. The overall goal of this project is to develop an experimentally validated simulation model to optimize fiber deposition purposefully. As a practical demonstration of achieving this goal, the simulation model will be used to improve the homogeneity of nonwoven patterns by leveraging the Coanda effect.

• DFG Programme: Research Grants