Fiber Drawing Modeling Quiz

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A young engineer at DuPont has been recently assigned to the nylon fiber spinning department.  The engineer wishes to build an empirical models to better understand how changes in the fiber drawing process affect the final properties of the fiber.  To complete the model in the brief time he has been give, he choose to simplify the modeling effort by assuming an isothermal drawing process.  The intent of such an effort is to help his customers reduce the time necessary to develop new products via computer simulations of their fiber drawing process.  From his polymer processing courses, the engineer knows that the viscosity of the polymer melt, the draw ratio, the length of the drawing section, and the take up velocity are all critical to his modeling efforts.  In addition, the engineer needs to build in the flexibility to accommodate the customer’s many products of various final fiber gauges.  To build the model, the engineer chooses a set of base conditions which include a polymer with a melt viscosity of 4,000 P, a draw ratio of 75:1, a drawing length of 300 cm, a take up velocity of 1,000 cm/second, and a final fiber gauge (diameter) of 10-3 cm.  Now the engineer must:

  1. Calculate the maximum stretching rate imposed on the fiber.
  2. Calculate the maximum tensile stress in the melt.
  3. Calculate the drawing force on the melt
  4. Determine at what point in the drawing process that internal effects become important.
  5. What potential effect will changing the draw ratio have on the processability and final properties of the fiber?

 

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