June 09, 2015 | by PolyXtrue | views 4807
Bi-layer flow in a profile coextrusion die was
simulated. Prediction of post-die changes in extrudate
profile was included in the simulation. Mesh partitioning
technique was used to allow the coextrusion simulation
without modifying the finite element mesh in the profile
die. Effect of polymer viscosities on the change in profile
shape after the polymers leave the die is analyzed. It is
found that a difference in the viscosities of the coextruded
polymers can lead to a highly non-uniform velocity
distribution at die exit. Accordingly, post-die changes in
extrudate shape were found to be widely different when
the polymers in the two coextruded layers were changed.
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Rheology
Plastics
Extrusion
PolyXtrue
Research Papers
April 28, 2015 | by Tod Dalrymple | views 4803
The purpose of this document is to describe a variety of test data that we have for a particular grade of polypropylene and demonstrate a calibration recipe that focuses on the nonlinear viscoelastic behavior of the material below yield
Plastics
Viscoelastic
Abaqus
January 17, 1994 | by DatapointLabs | views 4796
This book, edited by the Wisconsin based team of Osswald, Turng and Gramman, represents a compilation of work by several well known authors and brings together a body of knowledge that will be appreciated by injection molding professionals and students of plastics processing.
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Plastics
Injection Molding
Book Review
July 22, 2015 | by Paul Du Bois | views 4795
"During the past years polymer materials have gained enormous importance in the automotive industry. Especially
their application for interior parts to help in passenger safety load cases and their use for bumper fascias in pedestrian
safety load cases have driven the demand for much more realistic finite element simulations. For such applications
the material model 187 (i.e. MAT_SAMP-1) in LS-DYNA® has been developed.
In the present paper the authors show how the parameters for the rather general model may be adjusted to allow for
the simulation of crazing effects during plastic loading. Crazing is usually understood as inelastic deformation that
exhibits permanent volumetric deformations. Hence a material model that is intended to be applied for polymer
components that show crazing effects during the experimental study, should be capable to produce the correct volumetric
strains during the respective finite element simulation. The paper discusses the real world effect of crazing,
the ideas to capture these effect in a numerical model and exemplifies the theoretical ideas with a real world structural
component finite element model."
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Mechanical
Plastics
Rate Dependency
Automotive
High Speed Testing
LS-DYNA
Research Papers
May 06, 2016 | by Megan Lobdell | views 4780
I found this to be a good explanation of calculating linear Drucker Prager variables for Abaqus.
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Mechanical
Plastics
Plasticity
Nonlinear Material Models
Abaqus
July 31, 2015 | by Massimo Nutini | views 4763
Questo articolo si propone di illustrare l’importanza dell’utilizzo di metodi per la misura
delle proprietà locali del materiale per determinarne la legge di comportamento.
Vengono di seguito presentati alcuni esempi che evidenziano quanto più accurate
e realistiche siano le simulazioni numeriche di test di trazione ad alta velocità su provini
di poliolefine, quando vengano utilizzate proprietà dei materiali rilevate con misure locali,
utilizzando metodi ottici. La disponibilità di misure locali e più accurate evidenzia come sia
necessario che nei codici di calcolo commerciali vengano implementate delle leggi
di materiale più sofisticate di quelle disponibili attualmente, che sono state per lo più
originariamente sviluppate per materiali metallici, e dunque non riescono sempre a predire
correttamente il comportamento dei componenti in materiali polimerici.
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Mechanical
Plastics
Rate Dependency
Automotive
High Speed Testing
LS-DYNA
Research Papers
August 14, 1997 | by DatapointLabs | views 4763
This book presents a concise and easily readable introduction to polymer behavior for design and production engineers. It seeks to explain the behavior of plastics and rubber using a materials science framework, by relating observed phenomena to changes in morphological and molecular structure. This presents a powerful way for engineers to grasp the underlying factors that make polymers the complex materials that they are. The reader is encouraged to step away from using linear-elastic metals concepts when designing with plastics. The pitfalls of such
simplifications are pointed out and guidelines are presented to aid the designer in adopting a non-linear approach.
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Plastics
Rubbers
Nonlinear Material Models
Book Review
April 15, 1994 | by DatapointLabs | views 4757
Two approaches to polymer processing rheology are discernible; by theoreticians. who are concerned with a fundamental description of what would be happening if certain idealized criteria are met; and by practitioners, who are concerned with the results of what is actually happening.” In his newly revised book, Mr. Cogswell skillfully treads the middle ground between these camps, providing an interesting, informative guide to rheology for the design engineer.
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Rheology
Industrial Goods
Book Review
November 15, 2017 | by Altair Engineering | views 4737
Simulation uncertainties arise from different assumptions made in model creation. Mid-stage software validations improve confidence and optimize the design of additively manufactured aerospace components.
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Mechanical
Aerospace and Defense
Structural Analysis
Papers
Validation
3D Printing
June 09, 2015 | by PolyXtrue | views 4718
The flow in a coat-hanger die is simulated using the axisymmetric and planar elongational viscosities of a low-density polyethylene (LDPE) resin. Elongational viscosity is found to affect the velocity distribution at the die exit. Also, the predicted pressure drop in the die changed significantly when the effect of elongational viscosity was included in the simulation. However, elongational viscosity had only a minor effect on the temperature distribution in the die. Predicted pressure drop is compared with the corresponding experimental data.
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Rheology
Plastics
Extrusion
PolyXtrue
Research Papers
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