Optimization of an Extrusion Process for

Non-Newtonian high-viscous Fluids with

Wall Slip and Shear Thinning Effect

Wolfgang Hoffmann, Monika Scholz

SiCo-Solutions, Stuttgart, Germany

COMSOL Conference, Rotterdam, October 2013

SiCo – Solutions Scientific and Technical Solutions

SiCo–Solutions

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Agenda: Visco-plastic materials

Measurement of material parameters

Simulation of the flow in a forming die

Conclusions

SiCo–Solutions

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Examples of visco-plastic materials Silly putty

Heavy clay

Technical ceramics

Noodles, ketchup, food

Aluminum

Blood

Plastics

Rubber

Polymers

.....................

SiCo–Solutions Viscoplastic Materials

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Heavy clay industry

SiCo–Solutions Technical Ceramics

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SiCo–Solutions Die with pressure head

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Pressure sensor

strainer

SiCo–Solutions Characteristics of fluids

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Bingham-Fluid: yield stress

FF ,

SiCo–Solutions Wall slip

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HG

y

x

Low viscosity lubricating film

G

G

H

U ),( WGW kuf

Non-segregated clay material

SiCo–Solutions Material Parameters

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PSM developped for visco-plastic materials

4 characteristic parameters

expansion flow rheometer

kfactorwall

stressslipwall

osityvisBingham

stressyield

G

B

F

c

SiCo–Solutions Laboratory

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Screw extruder

Piston extruder

Measurement of material parameters

SiCo–Solutions Verifikation

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Reliabilty of the material modell, PSM

SiCo–Solutions Forming device

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Die with pressure head and fluid volume

SiCo–Solutions Velocity

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Velocity profile

SiCo–Solutions Velocity

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Velocity profile

SiCo–Solutions Pressure

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Pressure profile

SiCo–Solutions Viscosity

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Viscosity profile

SiCo–Solutions Shear rate

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Shear rate distribution

SiCo–Solutions wall slip velocity

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Wall slip velocity

SiCo–Solutions Conclsions

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Simulation of viscoplastic fluids needs wall slip computation for correct simulation Simulation and procedure technology is based on a Bingham modell with 4 parameters Determination of the characteristic material parameters including wall slip is possible with expansion flow rheometer COMSOL with extension PSM is an efficient tool for the analysis of the wide range of viscoplastic fluids