Predicting the co-extrusion flow of non-Newtonian fluids through rectangular ducts – A hybrid modeling approach

Hammer, Alexander; Roland, Wolfgang; Marschik, Christian; Steinbichler, Georg

doi:10.1016/j.jnnfm.2021.104618

Cited by 12 publications

(21 citation statements)

References 21 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The latter is an iterative population-based evolutionary algorithm, which creates a population of random mathematical models and refines them iteratively. The usefulness of the modeling approach was demonstrated in various polymer-processing problems [45][46][47][48][49][50].…”

Section: Symbolic Regression Analysismentioning

confidence: 99%

Application of Mixing Rules for Adjusting the Flowability of Virgin and Post-Consumer Polypropylene as an Approach for Design from Recycling

Traxler¹,

Marschik²,

Farthofer

et al. 2022

Polymers

Self Cite

View full text Add to dashboard Cite

To enable the use of recyclates in thermoformed polypropylene products with acceptable optical appearance and good mechanical stability, a multilayer structure of virgin and recycled material can be used. When producing multilayer films with more than two layers, the used materials should have similar melt flow properties to prevent processing instabilities. In the case of a three-layer film, post-consumer recyclates are often hidden in the core layer. Due to the inconsistent melt flow properties of post-consumer recyclates, the adjustment of the melt flow properties of the core layer to those of the outer layers has to be realized by blending with virgin materials. In order to understand the effect of mixing with a virgin material with a certain pre-defined melt flow rate (MFR), material mixtures with different mixing partners from various sources were realized in this study. Hence, the pre-defined virgin material was mixed with (i) virgin materials, (ii) artificial recyclates out of a mixture of different virgin materials, and (iii) commercially available recyclates. These blends with mixing partner contents ranging from 0–100% in 10% increments were prepared by compounding and the MFR of each mixture was determined. For a mathematical description of the mixing behavior and furthermore for a proper MFR prediction of the material mix, existing mixing rules were tested on the three pre-defined sample groups. Therefore, this paper shows the applicability of different mixing rules for the prediction of the MFR of material blends. Furthermore, a new mixing rule was developed using symbolic regression based on genetic programming, which proved to be the most accurate predictive model.

show abstract

Section: Symbolic Regression Analysismentioning

confidence: 99%

Application of Mixing Rules for Adjusting the Flowability of Virgin and Post-Consumer Polypropylene as an Approach for Design from Recycling

Traxler¹,

Marschik²,

Farthofer

et al. 2022

Polymers

Self Cite

View full text Add to dashboard Cite

show abstract

“…To predict the exact position of the interface within the co-extrusion flow of adhesive and HDPE through the die with rectangular cross-section, we applied a symbolic regression model developed as part of our previous work [43,44]. Using a power-law model according to Ostwald and de Waele to consider the shear rate dependency of viscosities, we found that such flow situations (and, thus, the interface position) can be fully described by a set of four independent dimensionless parameters-namely, (1) the power-law index of fluid A n A , (2) the power-law index of fluid B n B , (3) the ratio of dimensionless pressure gradients χ, and (4) the dimensionless volume flow rate of fluid A Π A V .…”

Section: Flow Modelingmentioning

confidence: 99%

In Situ Detection of Interfacial Flow Instabilities in Polymer Co-Extrusion Using Optical Coherence Tomography and Ultrasonic Techniques

et al. 2021

Self Cite

View full text Add to dashboard Cite

Co-extrusion is a widely used processing technique for combining various polymers with different properties into a tailored multilayer product. Individual melt streams are combined in a die to form the desired shape. Under certain conditions, interfacial flow instabilities are observed; however, fundamental knowledge about their onset and about critical conditions in science and industry is scarce. Since reliable identification of interfacial co-extrusion flow instabilities is essential for successful operation, this work presents in situ measurement approaches using a novel co-extrusion demonstrator die, which is fed by two separate melt streams that form a well-controlled two-layer co-extrusion polymer melt flow. An interchangeable cover allows installation of an optical coherence tomography (OCT) sensor and of an ultrasonic (US) measurement system, where the former requires an optical window and the latter good direct coupling with the cover for assessment of the flow situation. The feasibility of both approaches was proven for a material combination that is typically found in multilayer packaging applications. Based on the measurement signals, various parameters are proposed for distinguishing reliably between stable and unstable flow conditions in both measurement systems. The approaches presented are well suited to monitoring for and systematically investigating co-extrusion flow instabilities and, thus, contribute to improving the fundamental knowledge about instability onset and critical conditions.

show abstract

“…Rather, the approach applies evolutionary computation methods to uncover mathematical relationships based on comprehensive datasets. The usefulness of this modeling approach was demonstrated for various polymer-processing problems [ 134 , 135 ].…”

Section: Approximate Methodsmentioning

confidence: 99%

Melt Conveying in Single-Screw Extruders: Modeling and Simulation

Marschik¹,

Roland

Osswald

2022

Polymers

Self Cite

View full text Add to dashboard Cite

Numerous analyses have modeled the flow of polymer melts in the melt-conveying zones of single-screw extruders. While initial studies mainly provided exact analytical results for combined drag and pressure flows of Newtonian fluids, more recently developed, numerical methods seek to deepen the understanding of more realistic flow situations that include shear-thinning and non-isothermal effects. With the advent of more powerful computers, considerable progress has been made in the modeling and simulation of polymer melt flows in single-screw extruders. This work reviews the historical developments from a methodological point of view, including (1) exact analytical, (2) numerical, and (3) approximate methods. Special attention is paid to the mathematical models used in each case, including both governing flow equations and boundary conditions. In addition, the literature on leakage flow and curved-channel systems is revisited.

show abstract

Predicting the co-extrusion flow of non-Newtonian fluids through rectangular ducts – A hybrid modeling approach

Cited by 12 publications

References 21 publications

Application of Mixing Rules for Adjusting the Flowability of Virgin and Post-Consumer Polypropylene as an Approach for Design from Recycling

Application of Mixing Rules for Adjusting the Flowability of Virgin and Post-Consumer Polypropylene as an Approach for Design from Recycling

In Situ Detection of Interfacial Flow Instabilities in Polymer Co-Extrusion Using Optical Coherence Tomography and Ultrasonic Techniques

Melt Conveying in Single-Screw Extruders: Modeling and Simulation

Contact Info

Product

Resources

About