Nonwoven filter media are getting more and more important due to their versatile properties. Nonwovens are classified by their production process. Mainly, there are three different nonwoven production processes: dry-lay processes, wet-lay processes, and extrusion processes. Here, we focus on the simulation of extrusion processes with the so-called spunbond and meltblown processes as their most important representatives.
In principle, a spunbond or a meltblown process consists of the process steps extrusion, spinning, drawing, laying down on a conveyor belt, and bonding. The main difference between spunbond and meltblown processes is that in the meltblown process heated air with high speed is injected slightly beneath the spinnerets such that finer fibers are produced.
The Fraunhofer ITWM has developed a simulation tool called FIDYST in order to simulate the dynamics of the spun fibers and their lay down on the belt. FIDYST is an acronym for Fiber Dynamics Simulation Tool. The software implements a fiber dynamics model that is based on the Cosserat rod theory. In order to compute the dynamics of the fibers, the external forces acting on the fibers must be simulated. For spunbond and meltblown processes, the main forces are the aerodynamic forces, but gravity and contact forces of fibers with machinery parts are also included. For the simulation of the aerodynamics forces, the Fraunhofer ITWM has developed an air drag model. Together with a CFD simulation of the air flow the external forces are computed including the turbulent effects of the air. Additionally, FIDYST simulates the lay down on the belt, judges the quality, and exports the results to GeoDict®.
In this paper, we present the simulation tool FIDYST and its application to spunbond or meltblown processes...
Session: F4 - Filter Media - Numerical Methods for Optimized Media Design I
Day: 14 March 2018
Time: 16:45 - 18:00 h