1 Comparison of One-Hole Die Shape Fermi National Accelerator Laboratory (FNAL) Department of Mechanical Engineering Northern Illinois University Northern Illinois Center for Accelerator and Detector Development (NICADD) By Dr. Meung Kim & Prasad Rayasam

Contents 1.Objective Dimensions of Extrudate 2.Inverse Analysis with Remeshing 3.Mesh Refinement Study 4.Calibrator 5.Material Parameters

3 Objective Dimensions of the Extrudate Desired Dimensions of the Extrudate Units: CM 0.11

4 Inverse Analysis with Remeshing According to PolyFlow manual three sections must be modeled as “For the section to be maintained at a constant shape, constant section for prediction is selected instead of Adaptive section for prediction. POLFYLOW is to compute the shape (referred to as the adaptive section of the die), based on the specified extrudate shape.”

5 No.of elements on this face = 450 Model Half Domain Mesh Refinement Study  Mesh refinement in two different directions – along the longitudinal direction and transverse direction.  The inlet of adaptive section is updated based on constant section obtained by inverse analysis.

6  Max no.of elements is limited by memory  Much better ear shape is observed using more elements.  In all cases the initial adaptive section that was rectangular is modified similar to constant section after inverse analysis to get smooth transition. Mesh Refinement: Half Domain

7 Mesh Refinement: Quarter Domain Model Quarter domain (Final Result) with 1.5 inches of free surface

8 Comparison of Profiles Other Team Our Team Existing

9 Sample Extrudate: Experiment Both profiles of the sample extrudates measured by (a) our team and (b) the other team [1] are much larger than objective size (2 x 1 cm) of extrudate. [1] (a) (b)

10 Comparison of Desired and Simulated Extrudate by Direct Extrusion Case B in previous quarter domain simulation

11 Comparison Die Section – Dimensions (mm) Center Width Center Height Major Hole Dia. Minor Hole Dia. Existing Die Our Team Other Team Experimental Our Simulated Objective

12 Observations & Discussion 1.Existing Die gives Larger Dimensions of the Extrudate than Objective with Rounded Corners. 2.For Desired Extrudate of 2 x 1 cm ² with 90º Corners, it seems that the die must be smaller and needs to have ears as shown in our simulation.

13 Observations & Discussion 1.The simulation is based on rigorous computational analysis. Convergence analysis in x-y and z-directions was performed until converged result was obtained. Consistent to standard extrusion analysis, three sections of transition, constant, and free-surface were used to make sure that the extrudate remains constant after the end of free surface. A material function fits the experimental data for all temperatures. Gravitational effect has been checked out to be negligible. Though isothermal and non-isothermal simulations give closer results, non-isothermal simulations with temperature-dependent viscosity are carried out. Improving adaptive section after inverse analysis. Use long enough length of free surface to insure that the velocity remains constant.

14 Polymat is used to curve fit the viscosity – shear rate data using Carreau Yasuda law for Styron 663add at three different temperatures using Arrhenious Shear stress law. Plot of polymer viscosity as a function of shear rate and temperature Material Parameters - Styron 663add

15 Styron 663add Zero-Shear Rate Viscosity E E+4 Infinite Shear Rate Viscosity 0.433E E-3 Natural Time Slope Transition Parameter alfa (temp) Talfa (ref) Material Parameters

16 Face Mesh

17 Transition Region

18 Exploded view of Assembly

19 2-D Drawing for Top Die

20 2-D Drawing for Pin

21 Inlet Die Lip Transition Lip

22 Thank You