Modelling

18 pages, 2121 KiB

Open AccessArticle

Li⁺ Separation from Multi-Ionic Mixtures by Nanofiltration Membranes: Experiments and Modeling

by Tobias Hubach, Marcel Pillath, Clemens Knaup, Stefan Schlüter and Christoph Held

Modelling 2023, 4(3), 408-425; https://doi.org/10.3390/modelling4030024 - 20 Sep 2023

Viewed by 1177

Aqueous sources like salt lake brines and seawater are the most abundant source for lithium ions and might contribute to the growing demand for lithium for energy storage. By coupling with the increasingly relevant reverse osmosis systems, nanofiltration can provide a promising process [...] Read more.

Aqueous sources like salt lake brines and seawater are the most abundant source for lithium ions and might contribute to the growing demand for lithium for energy storage. By coupling with the increasingly relevant reverse osmosis systems, nanofiltration can provide a promising process alternative to conventional methods such as water evaporation and salt precipitation from ores or brines for this purpose. One possible model for nanofiltration is the solution-diffusion-electromigration model (SDEM). First, the model was parametrized by determining the permeances from simple electrolyte mixtures containing two salts. Then, the SDEM was used to predict the rejections of complex multi-electrolyte solutions that mimic seawater and reverse osmosis brine, without fitting additional parameters to experimental data of this complex mixture. This allowed predicting ion rejections satisfactorily. Negative rejections due to spontaneously generated electric fields in the membrane could also be qualitatively described. In summary, this SDEM modeling can provide an important contribution to the purification of Li⁺ from aqueous sources. Full article

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14 pages, 26529 KiB

Open AccessArticle

Investigating Ice Loads on Subsea Pipelines with Cohesive Zone Model in Abaqus

by Igor Gribanov, Rocky Taylor, Jan Thijssen and Mark Fuglem

Modelling 2023, 4(3), 394-407; https://doi.org/10.3390/modelling4030023 - 14 Sep 2023

Viewed by 880

Abstract

Subsea pipelines and cables placed in ice-prone regions may be at risk of iceberg damage. In particular, pipes that are not buried may come in direct contact with iceberg keels. Knowing the range of interaction forces helps to assess the types and magnitudes [...] Read more.

Subsea pipelines and cables placed in ice-prone regions may be at risk of iceberg damage. In particular, pipes that are not buried may come in direct contact with iceberg keels. Knowing the range of interaction forces helps to assess the types and magnitudes of potential damage. Experimental studies provide the most valuable data about the interaction forces, while numerical modeling may give insight into configurations that are difficult to study experimentally. This work applies the cohesive zone model to investigate the fracture behavior of ice samples. Simulations are performed in 2D with Abaqus explicit solver. Modeled interaction forces from multiple simulations are recorded and compared to understand how the geometry of the samples affects the fracture. Repeat interactions with different grain configurations are conducted to investigate associated variance in fracture patterns and loads. t-tests show that the force application angle and the indenter’s position significantly affect the fracture force. Full article

(This article belongs to the Special Issue Modeling Dynamic Fracture of Materials)

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12 pages, 3908 KiB

Open AccessArticle

Modelling and Simulating the Digital Measuring Twin Based on CMM

by Miladin A. Marjanovic, Slavenko M. Stojadinovic and Sasa T. Zivanovic

Modelling 2023, 4(3), 382-393; https://doi.org/10.3390/modelling4030022 - 17 Aug 2023

Cited by 1 | Viewed by 1335

Abstract

In order to perform the inspection planning process on the coordinate measuring machine (CMM), it is necessary to model the measuring system with workpiece, CMM and fixture. The metrological analysis of the workpiece is then conducted, followed by the creation of a measurement [...] Read more.

In order to perform the inspection planning process on the coordinate measuring machine (CMM), it is necessary to model the measuring system with workpiece, CMM and fixture. The metrological analysis of the workpiece is then conducted, followed by the creation of a measurement program for simulation on a virtual measuring machine in a CAD environment. This paper presents the modelling and simulation of a virtual measuring system based on a real CMM using PTC Creo Parametric 5.0 software. The simulation involved programming the measuring path and generating a DMIS (*.ncl) file, which represents the standard modelled types of tolerance. The analysis of the metrology of the measuring part for the given forms of tolerance (location, perpendicularity, flatness, etc.) was performed. The components of the CMM and the assembly with defined kinematic connections are also modelled. Following the simulation and generation of the output DMIS file in PTC Creo using the virtual CMM, the real CMM was programmed and used for actual measurements. Subsequently, a measurement report was generated. The main result of this paper is the modelling of an offline Digital Measuring Twin (DMT) based on the DMIS file. Full article

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16 pages, 1654 KiB

Open AccessArticle

A Second-Order Dynamic Friction Model Compared to Commercial Stick–Slip Models

by Georg Rill and Matthias Schuderer

Modelling 2023, 4(3), 366-381; https://doi.org/10.3390/modelling4030021 - 11 Aug 2023

Cited by 4 | Viewed by 1668

Abstract

Friction has long been an important issue in multibody dynamics. Static friction models apply appropriate regularization techniques to convert the stick inequality and the non-smooth stick–slip transition of Coulomb’s approach into a continuous and smooth function of the sliding velocity. However, a regularized [...] Read more.

Friction has long been an important issue in multibody dynamics. Static friction models apply appropriate regularization techniques to convert the stick inequality and the non-smooth stick–slip transition of Coulomb’s approach into a continuous and smooth function of the sliding velocity. However, a regularized friction force is not able to maintain long-term stick. That is why dynamic friction models were developed in recent decades. The friction force depends herein not only on the sliding velocity but also on internal states. The probably best-known representative, the LuGre friction model, is based on a fictitious bristle but realizes a too-simple approximation. The recently published second-order dynamic friction model describes the dynamics of a fictitious bristle more accurately. It is based on a regularized friction force characteristic, which is continuous and smooth but can maintain long-term stick due to an appropriate shift in the regularization. Its performance is compared here to stick–slip friction models, developed and launched not long ago by commercial multibody software packages. The results obtained by a virtual friction test-bench and by a more practical festoon cable system are very promising. Thus, the second-order dynamic friction model may serve not only as an alternative to the LuGre model but also to commercial stick–slip models. Full article

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15 pages, 2506 KiB

Open AccessArticle

Modeling of Human-Exoskeleton Alignment and Its Effect on the Elbow Flexor and Extensor Muscles during Rehabilitation

by Clarissa Rincon, Pablo Delgado, Nils A. Hakansson and Yimesker Yihun

Modelling 2023, 4(3), 351-365; https://doi.org/10.3390/modelling4030020 - 20 Jul 2023

Viewed by 1058

Abstract

Human-exoskeleton misalignment could lead to permanent damages upon the targeted limb with long-term use in rehabilitation. Hence, achieving proper alignment is necessary to ensure patient safety and an effective rehabilitative journey. In this study, a joint-based and task-based exoskeleton for upper limb rehabilitation [...] Read more.

Human-exoskeleton misalignment could lead to permanent damages upon the targeted limb with long-term use in rehabilitation. Hence, achieving proper alignment is necessary to ensure patient safety and an effective rehabilitative journey. In this study, a joint-based and task-based exoskeleton for upper limb rehabilitation were modeled and assessed. The assessment examined and quantified the misalignment present at the elbow joint as well as its effects on the main flexor and extensor muscles’ tendon length during elbow flexion-extension. The effects of the misalignments found for both exoskeletons resulted to be minimal in most muscles observed, except the anconeus and brachialis. The anconeus muscle demonstrated a relatively higher variation in tendon length with the joint-based exoskeleton misalignment, indicating that the task-based exoskeleton is favored for tasks that involve this particular muscle. Moreover, the brachialis demonstrated a significantly higher variation with the task-based exoskeleton misalignment, indicating that the joint-based exoskeleton is favored for tasks that involve the muscle. Full article

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15 pages, 1751 KiB

Open AccessArticle

High-Throughput Numerical Investigation of Process Parameter-Melt Pool Relationships in Electron Beam Powder Bed Fusion

by Christoph Breuning, Jonas Böhm, Matthias Markl and Carolin Körner

Modelling 2023, 4(3), 336-350; https://doi.org/10.3390/modelling4030019 - 10 Jul 2023

Cited by 2 | Viewed by 1435

Abstract

The reliable and repeatable fabrication of complex geometries with predetermined homogeneous properties is still a major challenge in electron beam powder bed fusion (PBF-EB). Although previous research identified a variety of process parameter–property relationships, the underlying end-to-end approach, which directly relates process parameters [...] Read more.

The reliable and repeatable fabrication of complex geometries with predetermined homogeneous properties is still a major challenge in electron beam powder bed fusion (PBF-EB). Although previous research identified a variety of process parameter–property relationships, the underlying end-to-end approach, which directly relates process parameters to material properties, omits the underlying thermal conditions. Since the local properties are governed by the local thermal conditions of the melt pool, the end-to-end approach is insufficient to transfer predetermined properties to complex geometries and different processing conditions. This work utilizes high-throughput thermal simulation for the identification of fundamental relationships between process parameters, processing conditions, and the resulting melt pool geometry in the quasi-stationary state of line-based hatching strategies in PBF-EB. Through a comprehensive study of over 25,000 parameter combinations, including beam power, velocity, line offset, preheating temperature, and beam diameter, process parameter-melt pool relationships are established, processing boundaries are identified, and guidelines for the selection of process parameters to the achieve desired properties under different processing conditions are derived. Full article

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13 pages, 1664 KiB

Open AccessArticle

Modelling of the Solidifying Microstructure of Inconel 718: Quasi-Binary Approximation

by Nikolai Kropotin, Yindong Fang, Chu Yu, Martin Seyring, Katharina Freiberg, Stephanie Lippmann, Tatu Pinomaa, Anssi Laukkanen, Nikolas Provatas and Peter K. Galenko

Modelling 2023, 4(3), 323-335; https://doi.org/10.3390/modelling4030018 - 22 Jun 2023

Cited by 1 | Viewed by 1078

Abstract

The prediction of the equilibrium and metastable morphologies during the solidification of Ni-based superalloys on the mesoscopic scale can be performed using phase-field modeling. In the present paper, we apply the phase-field model to simulate the evolution of solidification microstructures depending on undercooling [...] Read more.

The prediction of the equilibrium and metastable morphologies during the solidification of Ni-based superalloys on the mesoscopic scale can be performed using phase-field modeling. In the present paper, we apply the phase-field model to simulate the evolution of solidification microstructures depending on undercooling in a quasi-binary approximation. The results of modeling are compared with experimental data obtained on samples of the alloy Inconel 718 (IN718) processed using the electromagnetic leviatation (EML) technique. The final microstructure, concentration profiles of niobium, and the interface-velocity–undercooling relationship predicted by the phase field modeling are in good agreement with the experimental findings. The simulated microstructures and concentration fields can be used as inputs for the simulation of the precipitation of secondary phases. Full article

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Modelling, Volume 4, Issue 3 (September 2023) – 7 articles

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