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Thermal Cutting of Steel Plates : Modelling, Simulation and Optimal Control of Preheating Strategies = = Thermisches Schneiden von Stahlplatten.

Record Type:	Electronic resources : Monograph/item
Title/Author:	Thermal Cutting of Steel Plates : Modelling, Simulation and Optimal Control of Preheating Strategies =/
Reminder of title:	Thermisches Schneiden von Stahlplatten.
Author:	Arenas Jaen, Manuel Jesus.
Published:	Ann Arbor : ProQuest Dissertations & Theses, : 2021,
Description:	109 p.
Notes:	Source: Dissertations Abstracts International, Volume: 83-03, Section: B.
Contained By:	Dissertations Abstracts International83-03B.
Subject:	Cold. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=28663395
ISBN:	9798522954215

Thermal Cutting of Steel Plates : Modelling, Simulation and Optimal Control of Preheating Strategies = = Thermisches Schneiden von Stahlplatten.
Arenas Jaen, Manuel Jesus.

Thermal Cutting of Steel Plates : Modelling, Simulation and Optimal Control of Preheating Strategies =Thermisches Schneiden von Stahlplatten. - Ann Arbor : ProQuest Dissertations & Theses, 2021 - 109 p.

Source: Dissertations Abstracts International, Volume: 83-03, Section: B.

Thesis (Ph.D.)--Technische Universitaet Berlin (Germany), 2021.

This item must not be sold to any third party vendors.

Steel is commonly delivered as coils, sheets or plates at the final stages of production. The plates have to be cut to the right dimensions and this is usually done by means of thermal cutting. Flame cutting is a common and versatile method to produce steel plates but it can cause undesired side effects. Till date, the flame cutting process has not been thoroughly studied using mathematical modelling and numerical simulations. The present work describes a 3D quasi-stationary state (QSS) model to understand the distribution of the heat in a steel plate including solid-solid and solid-liquid transitions during the flame cutting process. Simulations are carried out employing the finite element method. They are able to predict the size of the kerf and the heat affected zone. Recent experimental research has proved that slower speed and adding a preheating stage helps reducing the side effects of flame cutting. The current practice of preheating consists in globally preheating the plates uniformly. We study an alternative preheating method wherein, local induction is applied just before flame cutting. The method involves using an induction coil on top of the cutting line to preheat the area of the plate to be affected by the flame. In induction, heating is done by electromagnetic fields. Due to the ferromagnetic nature of steel, induced eddy currents are generated directly in the workpiece which then cause heating by the Joule effect. We use a 3D eddy currents model in the harmonic regime coupled with the QSS heat equation. The simulations showcase that the heating is concentrated in the surface due to the skin effect. This heat is transported by conduction to the bottom and some time after the position of the coil, uniform temperature is achieved in the cutting line. The setting described has been replicated in a laboratory for experimental validation and the measurements show similar trends to the numerical simulation results. The induction preheating concept is influenced by many parameters which makes finding the optimal setting an unfeasible task. To overcome this, the flame cutting system was decoupled from the electromagnetic problem. The electromagnetic joule heat source was substituted by a parametric heat source and was optimised by an optimal control approach. Analysis of this system has been done to prove the existence, uniqueness and regularity of the solutions of the partial differential equation system. A difficulty of the system is that it includes a quasilinear elliptic heat equation coupled to QSS phase fraction equations. First order optimality conditions are derived for the nonlinear elliptic system. A steepest descent algorithm is implemented to solve the optimal control problem. The algorithm provides promising results to match the cutting speed and thicknesses that require different levels of preheating. Moreover, the control is forced to have a similar distribution as the dissipated power that can be obtained by induction heating. The results of the thesis show that the employment of induction preheating in a real industrial process is indeed feasible. This could lead to the integration of this novel method of preheating in the manufacturing chain, influencing positively on the production rate and energy efficiency of the steel plates production.

ISBN: 9798522954215Subjects--Topical Terms:

560283
Cold.

Thermal Cutting of Steel Plates : Modelling, Simulation and Optimal Control of Preheating Strategies = = Thermisches Schneiden von Stahlplatten.
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100 1 $a Arenas Jaen, Manuel Jesus. $3 3686388
245 1 0 $a Thermal Cutting of Steel Plates : Modelling, Simulation and Optimal Control of Preheating Strategies = $b Thermisches Schneiden von Stahlplatten.
260 1 $a Ann Arbor : $b ProQuest Dissertations & Theses, $c 2021
300 $a 109 p.
500 $a Source: Dissertations Abstracts International, Volume: 83-03, Section: B.
500 $a Advisor: Homberg, Dietmar;Pedreira, Maria Dolores Gomez;Schmidt, Alfred.
502 $a Thesis (Ph.D.)--Technische Universitaet Berlin (Germany), 2021.
506 $a This item must not be sold to any third party vendors.
520 $a Steel is commonly delivered as coils, sheets or plates at the final stages of production. The plates have to be cut to the right dimensions and this is usually done by means of thermal cutting. Flame cutting is a common and versatile method to produce steel plates but it can cause undesired side effects. Till date, the flame cutting process has not been thoroughly studied using mathematical modelling and numerical simulations. The present work describes a 3D quasi-stationary state (QSS) model to understand the distribution of the heat in a steel plate including solid-solid and solid-liquid transitions during the flame cutting process. Simulations are carried out employing the finite element method. They are able to predict the size of the kerf and the heat affected zone. Recent experimental research has proved that slower speed and adding a preheating stage helps reducing the side effects of flame cutting. The current practice of preheating consists in globally preheating the plates uniformly. We study an alternative preheating method wherein, local induction is applied just before flame cutting. The method involves using an induction coil on top of the cutting line to preheat the area of the plate to be affected by the flame. In induction, heating is done by electromagnetic fields. Due to the ferromagnetic nature of steel, induced eddy currents are generated directly in the workpiece which then cause heating by the Joule effect. We use a 3D eddy currents model in the harmonic regime coupled with the QSS heat equation. The simulations showcase that the heating is concentrated in the surface due to the skin effect. This heat is transported by conduction to the bottom and some time after the position of the coil, uniform temperature is achieved in the cutting line. The setting described has been replicated in a laboratory for experimental validation and the measurements show similar trends to the numerical simulation results. The induction preheating concept is influenced by many parameters which makes finding the optimal setting an unfeasible task. To overcome this, the flame cutting system was decoupled from the electromagnetic problem. The electromagnetic joule heat source was substituted by a parametric heat source and was optimised by an optimal control approach. Analysis of this system has been done to prove the existence, uniqueness and regularity of the solutions of the partial differential equation system. A difficulty of the system is that it includes a quasilinear elliptic heat equation coupled to QSS phase fraction equations. First order optimality conditions are derived for the nonlinear elliptic system. A steepest descent algorithm is implemented to solve the optimal control problem. The algorithm provides promising results to match the cutting speed and thicknesses that require different levels of preheating. Moreover, the control is forced to have a similar distribution as the dissipated power that can be obtained by induction heating. The results of the thesis show that the employment of induction preheating in a real industrial process is indeed feasible. This could lead to the integration of this novel method of preheating in the manufacturing chain, influencing positively on the production rate and energy efficiency of the steel plates production.
520 $a Stahl wird ublicherweise in der Endphase der Produktion als Spulen, Bleche oder Platten geliefert. Die Platten mussen auf die richtigen Abmessungen zugeschnitten werden, und dies erfolgt normalerweise durch thermisches Schneiden. Das Flammenschneiden ist eine ubliche und vielseitige Methode zur Herstellung von Stahlplatten, kann jedoch unerwunschte Nebenwirkungen verursachen. Bis heute wurde der Flammenschneidprozess mit mathematischen Modellen und numeri-schen Simulationen nicht grundlich untersucht. Die vorliegende Arbeit beschreibt ein 3D-Modell des quasi-stationaren Zustands (QSS), um die Verteilung der Warme in einer Stahlplatte einschlieslich Fest-Fest- und Fest-Flussig-Ubergangen wahrend des Flammenschneidprozesses zu verstehen. Simulationen werden nach der Finite-Elemente-Methode durchgefuhrt. Sie konnen die Grose der Schnittfuge und die Warmeeinflusszone vorhersagen. Jungste experimentelle Untersuchungen haben gezeigt, dass eine langsamere Geschwindigkeit und das Hinzufugen einer Vorheizstufe dazu beitragen, die Nebenwirkungen des Flammenschneidens zu verringern. Die derzeitige Praxis des Vorheizens besteht darin, die Platten global gleichmasig vorzuwarmen. Wir untersuchen ein alternatives Vorheizverfahren, bei dem die lokale Induktion unmittelbar vor dem Flammenschneiden angewendet wird. Das Verfahren beinhaltet die Verwendung einer Induktionsspule uber der Schneidlinie, um den Bereich der Platte, der von der Flamme betroffen sein soll, vorzuwarmen. Bei der Induktion erfolgt die Erwarmung durch elektromagnetische Felder. Aufgrund der ferromagnetischen Natur von Stahl werden direkt im Werkstuck induzierte Wirbelstrome erzeugt, die dann durch den Joule-Effekt eine Erwarmung verursachen. Wir verwenden ein 3D-Wirbelstrommodell im harmonischen Bereich in Verbindung mit der QSS-Warmegleichung. Die Simulationen zeigen, dass sich die Erwarmung aufgrund des Skin-Effekts in der Oberflache konzentriert. Diese Warme wird durch Warmeleitung nach unten transportiert und einige Zeit nach der Position der Spule wird eine gleichmasige Temperatur in der Schneidlinie erreicht. Die beschriebene Einstellung wurde zur experimentellen Validierung in einem Labor repliziert und die Messungen zeigen ahnliche Trends wie die numerischen Simulationsergebnisse. Das Induktionsvorwarmkonzept wird von vielen Parametern beeinflusst, was es unmoglich macht, die optimale Einstellung zu finden. Um dies zu uberwinden, wurde das Flammen-schneidsystem vom elektromagnetischen Problem entkoppelt. Die elektromagnetische Joule-Warmequelle wurde durch eine parametrische Warmequelle ersetzt und durch einen optimalen Steuerungsansatz optimiert. Die Analyse dieses Systems wurde durchgefuhrt, um die Existenz, Eindeutigkeit und Regelmasigkeit der Losungen des partiellen Differentialgleichungssystems zu beweisen. Eine Schwierigkeit des Systems besteht darin, dass es eine quasilineare elliptische Warmegleichung enthalt, die an QSS-Phasenfraktionsgleichungen gekoppelt ist. Optimalitatsbedingungen erster Ordnung werden fur das nichtlineare elliptische System abgeleitet. Ein Algorithmus fur den steilsten Abstieg wird implementiert, um das Problem der optimalen Steuerung zu losen. Der Algorithmus liefert vielversprechende Ergebnisse, um die Schnittgeschwindigkeit und -dicken anzupassen, die unterschiedliche Vorheizstufen erfordern. Daruber hinaus ist die Steuerung gezwungen, eine ahnliche Verteilung wie die Verlustleistung zu haben, die durch Induktionserwarmung erhalten werden kann. Die Ergebnisse der Arbeit zeigen, dass der Einsatz von Induktionsvorwarmung in einem realen industriellen Prozess tatsachlich machbar ist. Dies konnte zur Integration dieser neuartigen Vorheizmethode in die Fertigungskette fuhren und sich positiv auf die Produktionsrate und Energieeffizienz der Stahlblechproduktion auswirken.
590 $a School code: 1119.
650 4 $a Cold. $3 560283
650 4 $a Velocity. $3 3560495
650 4 $a Mimesis. $3 580418
650 4 $a Heat. $3 573595
650 4 $a Manufacturing. $3 3389707
650 4 $a Collaboration. $3 3556296
650 4 $a Materials science. $3 543314
650 4 $a Algorithms. $3 536374
650 4 $a Temperature. $3 711968
650 4 $a Industrial engineering. $3 526216
650 4 $a Simulation. $3 644748
650 4 $a Phenomenology. $3 533816
690 $a 0794
690 $a 0546
710 2 $a Technische Universitaet Berlin (Germany). $3 3480527
773 0 $t Dissertations Abstracts International $g 83-03B.
790 $a 1119
791 $a Ph.D.
792 $a 2021
793 $a English
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=28663395