Simulation of molten polymer extrusion with SPH ?

[Cosmin]

Hello all,

Has anyone performed any simulation with molten polymers and SPH ? I am trying to simulate an extrusion problem and have a hard time in finding some parameters for the material and EOS. The extruded polymer is ABS.

If anybody knows of any research on this topic or has any details, I would be very grateful.

Thanks,

Cosmin

[James M. Kennedy]

Dear Cosmin,

 

Several ABS references that may be of interest.

 

Quasi-static tensile tests of a polycarbonate PC/ABS (acrylonitrile butadiene styrene) were performed and elastic and inelastic deformation behavior of this material were determined. The Young’s modulus was determined by fitting a linear function to the stress vs strain curves of the tensile tests. Dynamic tensile tests and three point bending tests were performed to determine the strain rate behavior of the material. For the first step the coupon testes were simulated with von Mises plasticity (*MAT_024). Determination of the strain rate behavior by reverse engineering for the yield and damage behavior was shown. In a next step the plastic Poisson’s ratio was taken into account by using SAMP-1 material model (*MAT_187) in order to model and consider the increasing volumetric strain with increasing tensile load. The simulation of the bending tests was improved by the consideration of compression-tension asymmetry with the *MAT_187 model. Finally fracture modeling with increasing volumetric straining with the eGISSMO model (*MAT_ADD_EROSION) was shown:

 

Helbig, M., and Haufe, A., "Modeling of Crazing in Rubber-Toughened Polymers with LS-DYNA", 15th International LS-DYNA Users Conference, Dearborn, Michigan, June, 2018.

 

https://www.dynalook.com/15th-international-ls-dyna-conference/constitutive-modeling/modeling-of-crazing-in-rubber-toughened-polymers-with-ls-dyna-r

 

Two ductile, yet different materials, ABS and polypropylene, for rate-dependent tensile properties were characterized. The data was used to develop material parameters for the

material models commonly used for plastics: *MAT_024 and its variants, *MAT_089 and *MAT_181.

 

Lobdell, M., Croop, B., and Lobo, H., "Comparison of Crash Models for Ductile Plastics", 10th European LS-DYNA Users Conference, Wurzburg, Germany, May, 2015.

 

http://www.dynalook.com/10th-european-ls-dyna-conference/2%20Crash%20VI%20-%20Material/04-Lobo-DatapointLabs-P.pdf

 

Three LS-DYNA materials (*MAT_024, *MAT_089, and *MAT_187) were validated against a standardized dart impact tests. Validations were performed for two ductile plastics, an ABS, and a polypropylene. While the ABS exhibited no rate dependency of failure strain, the polypropylene showed rate dependency in both modulus and failure strain:

 

Lobdell, M., Croop, B., and Lobo, H., "A Standardized Mechanism to Validate Crash Models for Ductile Plastics", 14th International LS-DYNA Users Conference, Dearborn, Michigan, June, 2016.

 

http://www.dynalook.com/14th-international-ls-dyna-conference/constitutivemodeling/a-standardized-mechanism-to-validate-crash-models-for-ductile-plastics

 

equation-of-state possibilities:

 

Steinberg, D.J., "Equation of State and Strength Properties of Selected Materials", Lawrence Livermore National Laboratory, UCRL-MA-106439, Change 1, February 13, 1996.

 

Sincerely,

James M. Kennedy

KBS2 Inc.

January 17, 2021

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