The group 'flexible structures' concentrates on modeling and simulating flexible (elastic, viscous or viscoelastic) objects. Especially the simulation of fluid-structure-interactions is a main topic of this group. For the simulation of flexible structures simplified models can often be used. Thus we get the following classes of models:

• droplets, particles (mass points)
• fibers, filaments, staple fibers, cables,... (line shape objects)
• sheets of paper, plastic films (planar objects)

During the last years the simulation tool FIDYST (Fiber Dynamics Simulation Tool) was developed for the simulation of fibers in air flows. FIDYST was successfully used in several industrial projects to analyse and optimize fiber processes like nonwoven production or spinning processes. For the simulation of the fluid-structure-interactions the flow is simulated by commercial CFD tools. The flow results are input date for the structure simulation. For a fully coupled fluid-structure-interaction simulation the ssimulationtools for the flow and the structure have to be coupled in an iiterativescheme with appropriate models for the interactions.

For nonwoven processes stochastic models are developed to describe the trace of a fiber on the belt. After analysing the deterministic and stochastic properties of the FIDYST result, the stochastic model can compute a whole nonwoven which can be used for further examinations.

Projects

• Optimized needle boards based on simulations of needle punch patterns

  

  Needle punching is a well-established method to bond nonwovens mechanically. In this process thousands of barbed needles penetrate simultaneously into the nonwoven. Hereby, fibers captured by a needle are drawn through the layers of the nonwoven to solidify them.

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• Simulation-based Constructive Design of a Nonwoven Spunbond Plant

  

  Different projects for the design and optimization of machines and plants have been dealt with on the basis of the software tool FIDYST (Fiber Dynamics Simulation Tool). The essential key is to influence the dynamic behavior of specific filaments or staple fibers.

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• Simulation of the weft yarn in air weaving

  

  In air weaving the weft yarn is - in contrast to conventional procedures - transported not mechanically, but aerodynamically. For that purpose several nozzles are used in the weaving machine to produce an air flow that transports the weft yarn from one side to the other.

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• Production of nonwovens by ASON technology
• Movement of filaments in air flows

Products

• FIDYST - Fiber Dynamics Simulation Tool

  

  Starting point of the development of the software tool FIDYST was the simulation of nonwoven and spinning processes like spunbond or meltblown.

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