Yarn Dynamics in the Context of Warp Knitting

Beschreibung

In the textile industry, two major developments have been noted in recent years, which aim at increasing production quantities, structural variability and textile quality. The first development comprises the increase in performance of textile machines by higher machine speeds and greater working widths, which leads to a more cost-effective production of textile products. The second development concerns the production of tailored textile-based solutions (e.g. in the automotive and technical fields for FRP applications). Here, low permissible number of errors, high reproducible product quality, low machine downtime as well as the processability of high-quality yarn materials, like glass, carbon,aramid fibers and staple fiber yarns, are requirements to be met. The determination of interactions and dependencies between the different yarn materials, process parameters and yarn guide elements is essential for a significant improvement and thus for the homogenization of the yarn run. Moreover, this is made more difficult by the number of influencing parameters and the complex interaction of machine-specific and technological parameters. The aim of the project is therefore the research and modeling of short-time dynamic yarn handling processes in non-stationary operation through the example of high-performance warp knitting. This textile manufacturing technology is characterized by high yarn dynamics due to high processing speeds. This results in extremely short-time dynamic stress scenarios for the yarn running processes to be evaluated in terms of simulation and measurement technology. These dynamic stress scenarios comprise, amongst others, transverse accelerations with resulting transverse and longitudinal vibrations, including associated damping phenomena. In addition, dynamic alternating stresses caused by the discontinuous stitching process as well as by superimposed operating speed-dependent natural oscillations of the working elements have to be analyzed in-depth. These effects are of fundamental importance for the quality and stability of the textile manufacturing process. A comprehensive, coupled model is to be developed and validated for an accuratedescription of the complex machine and yarn dynamics as well as their interactions.