Name: a novel biaxial testing apparatus for the determination of forming limit under hot stamping conditions
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This research was supported by the European Union's Seventh Framework Programme (FP7/2007-2013) under grant agreement No. 604240, project title "An industrial system enabling the use of a patented, lab-proven materials processing technology for Low Cost forming of Lightweight structures for transportation industries (LoCoLite)."

1. Herstellung der Proben <ol><li> Maschine flache Hundeknochen und Kreuz Proben aus handelsüblichen Material Aluminiumlegierung 6082 (AA6082) mit Hilfe eines Laser-Schneideinrichtung und eine numerische Computersteuerung (CNC) Fräsmaschine (für Umformbarkeit Tests bei unterschiedlichen Dehnungswege einschließlich uniaxial, plane strain und gleichwinklig biaxialen Spann Staaten). </li><li> Messen Sie die Dicke jeder Kreuzprobe und jeder Hund-Knochenprobe mit einer Schieblehre dreimal im zentralen Kalibrierbereich und berechnen die Mittelwerte. Stellen Sie sicher, dass die Dicke des Kalibrierabschnitt in Kreuzprobe 0,7 ± 0,05 mm ist, und dass die Dicke der uniaxial Probe betragen 1,5 ± 0,1 mm. </li><li> Sprühfarbe die gesamte obere Oberfläche einer Kreuzprobe durch die Verwendung einer flammbeständigen, schwarz Sprühfarbe (geeignet für Temperaturen von bis zu 1.093 ° C widerstehen). Warten, bis die Farbe trocknet, und dann schwer entflammbare, weiße Farbe von Punkten Armlänge sprüht einen stochastischen zu erstellendurch das DIC - System erkannt werden (siehe das Beispiel in 1) Sprühbild. </li><li> Weld ein Paar Thermoelemente an der Mitte der Rückseite (entgegengesetzt zu der lackierten Oberfläche) der Probe. Das andere Ende des Thermoelementes mit dem Rückkopplungstemperatursteuersystem der uniaxialen Prüfmaschine zu überwachen und die Temperaturänderungshistorie zu steuern. </li></ol> 2. Zusammenbau der zweiachsigen Prüfvorrichtung <ol><li> Montieren Sie alle Teile der biaxialen Testvorrichtung, einschließlich einer Grundplatte, eine zentrale Welle, Eingangs- und Ausgang drehbarer Platten, Schlitten, eine Klammer, Führungsschienen und starre Verbindungsstangen (die zusammengebaute Vorrichtung ist in 2 gezeigt). <ol><li> Verwendung eines Pleuels, koppeln die Eingangs drehbare Platte direkt an der beweglichen Backe eines Widerstands uniaxial Zugprüfmaschine Heizung, die die uniaxiale Zugkraft zur Verfügung stellt. Koppeln die Eingangs drehbare Platte an der zentralen Antriebswelle undGepaart zentrale Antriebswelle auf den Abtrieb drehbare Platte. </li><li> Stellen Sie sicher, dass die Drehung der drehbaren Antriebsplatte um die Drehachse der Antriebswelle dreht sich, wodurch die Ausgangsdreh drehbare Platte, an das es gekoppelt um die Drehachse. </li><li> An einem Ende jedes Paar der starren Verbindungsstangen mit einem der Verbindungspunkte auf der Abtriebs drehbaren Platte. Paar das andere Ende an einem der Wagen. HINWEIS: Dadurch werden die Wagen mit Probenhaltern verursachen hin und her entlang der Führungsschienen mit geringer Reibung gleiten, die eine biaxiale Kraft auf die Kreuzprobe anwenden können. </li><li> Verwendung von Schraubenbolzen klemmen jeden Arm der kreuzförmigen Probe zu einem Wagen mit einem Probenhalter und einer oberen Platte. </li></ol></li><li> Richten Sie Griffe in der Kammer der einachsigen Zugversuch - Maschine, wie in Abbildung 3 (a). Befestigen vier Schweißkabel an jedes Paar von Griffen, die aus rostfreiem Stahl und Kupfer hergestellt sind, RESPEctively und so die Schweißkabel an die Stromversorgung angeschlossen werden. HINWEIS: Der Leiterbereich der Schweißkabel 50 mm 2 und die Stromstärke beträgt 345 A. <ol><li> Setzen Sie die Griffe und die Klemme der biaxialen Testvorrichtung in die beiden Backen der einachsigen Zugprüfmaschine und ziehen diese nach innen (Figur 3 (a)). </li></ol></li><li> Stellen Sie die biaxiale Testvorrichtung in der Kammer der einachsigen Zugversuch - Maschine, wie in 3 (b) gezeigt. <ol><li> Verwenden zwei Rahmen und Schraubenbolzen an dem oberen und unteren Seiten der Basisplatte, die die Vorrichtung in der Kammer der einachsigen Zugversuchs Maschine zu fixieren. </li><li> Setzen Sie die Probe in den Probenhalter auf der Oberseite der biaxial Testvorrichtung. </li><li> Verbinden jeden Anschlusses der Schweißkabel an jeden Klemmbereich der Probe. </li></ol></li></ol> 3. Aufbau der Heizung und Abschrecksystems <ol><li> dicht connect jeden Klemm Bereich der Probe auf die Edelstahldeckplatte, die für die Widerstandsheizung als Elektrode dient. </li><li> Ziehen Sie die Schweißkabel mit Crimpring Klemmen an der oberen Platte jedes Klemmbereich. </li><li> Connect aufgeweiteten Düsen mit Schläuchen an den hohen Strömungs Abschrecksystem mit geregelter Luftzufuhr bei 8.000 kg / m 2 Druck für die Kühlung. </li><li> Verwenden vier Düsen Luft aus den Armen der Probe auf den zentralen Bereich der Probe zu blasen. HINWEIS: Die Düsen sind nicht auf den Kalibrierabschnitt gerichtet zu vermeiden Kühlen die zentrale Zone aus der Sicht der Kamera blockiert. </li></ol> 4. Aufbau des DIC-System <ol><li> Schließen Sie die High-Speed-Kamera des DIC-Systems mit einer Mikrolinse auf einen Computer. Stellen Sie die Bildraten der Kamera 25 Bilder pro Sekunde, 50 fps, 500 fps und aus dem Menü der Frameraten (für die Tests an den Streck Dehnraten von 0,01 / s, 0,1 / s und 1 / s, jeweils). Stellen Sie die Auflösung aller iMages bis 1.280 × 1.024 Pixel. HINWEIS: Die Bildraten sind abhängig von der Anzahl der Datenpunkte gesammelt werden; mindestens 200 Datenpunkte können unter Verwendung der oben genannten Einstellungen gesammelt werden. </li><li> Verwenden einer zusätzlichen Strahler mit einer Leistung von 300 W für die Tests bei hohen Dehnungsraten. Weist die Scheinwerfer direkt an der Kammer der einachsigen Zugversuch-Maschine. </li><li> Justieren der Kameralinse, so dass es an der oberen Oberfläche der Probe in der Kammer und die Kamera auf dem Spurabschnitt parallel ist. </li></ol> 5. Experimentelle Programm <ol><li> Führen Sie den Widerstand uniaxial Zugprüfmaschine Erwärmung durch die dreieckförmigen Lauftaste in der Steuersoftware klicken. HINWEIS: Strom läuft durch das Material AA6082 und erhitzt es auf die Lösungswärmebehandlungstemperatur von 535 ° C 14 bei einer Heizrate von 30 ° C / s. Das Material wird bei 535 ° C für 1 min eingetaucht, die für die vollständige Auflösung der Ausscheidungen ausreichend ist. Air Einblasen aus dem Abschreckungssystem wird verwendet , um das Material mit einer Abkühlrate von 100 ° C / s von 15 bis einem von 3 bezeichneten erhöhten Temperaturen im Bereich von 370 bis 510 ° C quenchen. </li><li> Strecken, um die Probe mit der biaxialen Testvorrichtung mit konstanter Dehnungsrate im Bereich von 0,01-1 / s und Aufzeichnungshistorie der Verformung durch manuell den Auslöseknopf auf die Hochgeschwindigkeitskamera verbunden drücken. HINWEIS: Die Eingang Verschiebung von der einachsigen Prüfmaschine zur biaxialen Testvorrichtung wurde von der integrierten Software des einachsigen Prüfmaschine gesteuert. </li><li> Durchführen der Tests an unterschiedlichen Dehnungswege aus uniaxial, plane strain und biaxiales Spann Zustände 3 durch die Konfiguration der biaxialen Testvorrichtung anzupassen. <ol><li> Trennen zwei gegenüberliegenden Pleuelstangen für uniaxiale Tests. Klemme eine dog-bone Probe auf der biaxialen Testvorrichtung und verbindet es mit Schweißkabel, wie in den Schritten 3.1-3.4. Wiederholen Sie die Schritte 5,1-5,2. </li><li> Fix zwei gegenüberliegende Schlitten an der Grundplatte mit Schraubbolzen zum Testen gegen ebene Verformung des Verformungszustand an die entsprechende Richtung zu beschränken. Klemme eine Kreuz Probe auf der biaxialen Testvorrichtung und verbindet es mit Schweißkabel, wie in den Schritten 3,1-3,4. Wiederholen Sie die Schritte 5,1-5,2. </li></ol></li><li> Wiederholen Sie die Schritte 5.3.1-5.3.2 für jede Testbedingung dreimal mit neuen Hundeknochen und Kreuzproben. </li></ol> 6. Datenverarbeitung <ol><li> Importieren Sie alle Bilder von der High-Speed-Kamera in die Nachbearbeitungssoftware aufgezeichnet und folgen Standardschritten für die Datenanalyse nach dem Software-Handbuch. </li><li> Verwenden Sie die ISO - Norm 3 die Formgrenzen zu bestimmen , indem die FLC - Modus - Taste in der Software klicken. Hinweis: Diese Methode wurde bereits in die Bildkorrelationsverarbeitungssoftware integriert. </li><li> Markiert jedes Ergebnis der Formgrenzen bei verschiedener Temperaturs, Dehnraten und Dehnungspfade in einem Diagramm. </li><li> Zeichnen Sie die Grenzformänderungskurven bei allen Testbedingungen eine FLD aus einer Legierung unter Heißprägebedingungen zu erhalten. </li></ol>

<ol>
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K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Biaxial+warm+forming+behavior+of+aluminum+sheet+alloys.">Biaxial warm forming behavior of aluminum sheet alloys.</a> J. of Mater. Process. Tech. 145 (3), 281-293 (2004).</li><li>Palumbo, G., Sorgente, D., Tricarico, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+design+of+a+formability+test+in+warm+conditions+for+an+AZ31+magnesium+alloy+avoiding+friction+and+strain+rate+effects.">The design of a formability test in warm conditions for an AZ31 magnesium alloy avoiding friction and strain rate effects.</a> Int. J. Mach. Tool. Manu. 48 (14), 1535-1545 (2008).</li><li>Raghavan, K. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+simple+technique+to+generate+in-plane+forming+limit+curves+and+selected+applications.">A simple technique to generate in-plane forming limit curves and selected applications.</a> Metall. Mater. Trans. A. 26 (8), 2075-2084 (1995).</li><li>Ragab, A. R., Baudelet, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Forming+limit+curves:+out-of-plane+and+in-plane+stretching.">Forming limit curves: out-of-plane and in-plane stretching.</a> J. Mech. Work. 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Plasticity. 21 (8), 1640-1657 (2005).</li><li>Milkereit, B., Wanderka, N., Schick, C., Kessler, O. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Continuous+cooling+precipitation+diagrams+of+Al-Mg-Si+alloys.">Continuous cooling precipitation diagrams of Al-Mg-Si alloys.</a> Mater. Sci. Eng. A. 550, 87-96 (2012).</li><li>Crammond, G., Boyd, S. W., Dulieu-Barton, J. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Speckle+pattern+quality+assessment+for+digital+image+correlation.">Speckle pattern quality assessment for digital image correlation.</a> Opt. Laser. Eng. 51 (12), 1368-1378 (2013).</li></ol>

The authors have nothing to disclose.

Herkömmliche Formbarkeit verwendete Testverfahren zur Bestimmung Grenzen bilden, sind in der Regel nur anwendbar bei Raumtemperatur. Die dargestellte Technik kann verwendet werden, um die Formbarkeit von Metallen für die Heißprägefolie Anwendungen zu bewerten, indem eine neuartige biaxialen Testvorrichtung zu einem Widerstand Einführung uniaxial Prüfmaschine erhitzt wird. Dies kann mit konventionellen Methoden nicht für Heißpräge Anwendungen durchgeführt werden. Der Aufbau der Heiz- und Kühlsysteme und der DI...

Die Automobilindustrie steht vor einer große globale Herausforderung der Reduzierung des Kraftstoffverbrauchs und die Umweltbelastung durch Emissionen von Kraftfahrzeugen zu minimieren. Gewichtsreduzierung ist von Vorteil , um die Leistung der Autos zu verbessern und kann direkt den Energieverbrauch 1 reduzieren. Aufgrund der geringen Formbarkeit von Blechen bei Raumtemperatur werden die Warmumformung und Kaltform Abschreckverfahren (bezeichnet als Heißpräge) 2 verwendet , um die Formbarkeit von Legierungen zu verbessern und somit komplex geformte Bauteile in Automobilanwendungen zu erhalten. Ein Grenzformänderungsdiagramm (FLD) ist ein nützliches Werkzeug , um die Verformbarkeit einer Legierung 3 zu bewerten. Out-of-plane - Test, wie der Nakazima Test 4, 5 und in der Ebene liegende Tests, wie der Marciniak Test 6, 7, 8, einemre konventionelle Methoden , um die experimentellen flds von Blechen unter verschiedenen Bedingungen 9, 10, 11 zu erhalten. Eine servohydraulischen Prüfmaschine biaxialen hat auch die Formbarkeit der Legierung bei Raumtemperatur 12, 13 zu untersuchen , verwendet worden. Jedoch ist keines der obigen Verfahren sind anwendbar auf Formbarkeit Tests unter Heißprägebedingungen, da ein Kühlvorgang vor der Bildung benötigt wird zusammen mit der Steuerung der Heiz- und Kühlraten. Die Verformungstemperatur und Verformungsgeschwindigkeit lassen sich nur schwer genau zu erhalten. Daher wird ein neuartiges Umformbarkeit Prüfsystems in dieser Studie vorgeschlagen, experimentell die Formgebungsgrenzen von Blechen unter Heißprägebedingungen zu bestimmen.

<table><tbody><tr><td>Aluminium Alloy&amp;nbsp;</td><td>Smiths Metal</td><td>6082</td><td>Specimens machining</td></tr><tr><td>Laser cutter</td><td>LVD Ltd</td><td>HELIUS 25/13</td><td>Laser cutting specimens</td></tr><tr><td>CNC machine</td><td>HAAS Automation</td><td>TM-2CE</td><td>Machine specimens by milling</td></tr><tr><td>Vernier caliper</td><td>Mitutoyo</td><td>575-481</td><td>Thickness measurement</td></tr><tr><td>Resistance heating uniaxial testing machine</td><td>Dynamic System Inc</td><td>Gleeble 3800</td><td>Thermo-mechanical materials simulator</td></tr><tr><td>High flow quench system</td><td>Dynamic System Inc</td><td>38510</td><td>For air cooling</td></tr><tr><td>Thermocouples</td><td>Dynamic System Inc</td><td>K type</td><td></td></tr><tr><td>Nozzles</td><td>Indexa</td><td></td><td>Nozzle flared 1/4 inch bore</td></tr><tr><td>Welding cables</td><td>LAPP Group</td><td>H01N2-D</td><td></td></tr><tr><td>High-speed camera</td><td>Photron</td><td>UX50</td><td>For DIC testing</td></tr><tr><td>Camera lens</td><td>Nikon</td><td>Micro 200mm</td><td></td></tr><tr><td>Lamp</td><td>Liliput</td><td>150ce</td><td>300 W</td></tr><tr><td>Laptop</td><td>HP</td><td>Campaq 2530p</td><td>For images recording</td></tr><tr><td>Biaxial testing apparatus</td><td>Manufactured independently</td><td></td><td>All parts were designed and machinced by authors for biaxial testing</td></tr><tr><td>Steel&amp;nbsp;</td><td>West Yorkshire Steel</td><td>H13</td><td>Mateials of the biaxial testing apparatus</td></tr><tr><td>Image correlation processing software</td><td>GOM</td><td>ARAMIS</td><td>Non-contact measuring system and data post-pocessing</td></tr></tbody></table>

a novel biaxial testing apparatus for the determination of forming limit under hot stamping conditions

Die Heißprägung und Kaltform Abschreckvorgang wird zunehmend verwendet, komplex geformte Bauteile von Blechen zu bilden. Herkömmliche experimentelle Ansätze, wie aus der Ebene und in der Ebene liegenden Tests, sind nicht anwendbar auf die Bestimmungsgrenzen des Ausbildens beim Heizen und schnelle Abkühlen Prozesse werden vor der Bildung für die Tests durchgeführt unter Heißprägebedingungen eingeführt. Eine neue in-plane biaxialen Prüfsystems wurde für die Bestimmung von Formgebungsgrenzen von Blechen an verschiedenen Dehnungsweg, Temperaturen und Verformungsgeschwindigkeiten nach dem Erhitzen und Kühlprozess in einem Widerstandsheizelement uniaxial Prüfmaschine entworfen und verwendet. Der Kernteil des biaxialen Prüfsystems ist eine biaxiale Vorrichtung, die eine uniaxiale Kraft, die von der einachsigen Prüfmaschine bereitgestellt auf eine biaxiale Kraft. Eine Art von Kreuzprobe wurde konstruiert und für den Umformbarkeit Test der Aluminiumlegierung 6082 mit dem vorgeschlagenen biaxialen Prüfsystems verifiziert. Die digitale imAlters Korrelation (DIC) System mit einer Hochgeschwindigkeitskamera wurde für die Aufnahme Dehnungsmessungen einer Probe während einer Verformung verwendet. Das Ziel schlägt diese biaxiale Prüfsystems ist die Formgebungsgrenzen einer Legierung zu ermöglichen, bei verschiedenen Temperaturen und Verformungsgeschwindigkeiten unter Heißprägebedingungen bestimmt werden.

Da flds hochDehnungs wegabhängige sind, wurde die Linearität der Dehnungspfad für jede Testbedingung durch Analysieren der Ergebnisse DIC überprüft; die Dehnungswege sind im gesamten Verformung für jede Prüfbedingung proportional. Der Bereich des kleineren zu größeren Dehnungsverhältnis beträgt ca. -0.37 (uniaxial Zustand) bis 0,26 (bei biaxialer Bedingung). Von Daten für verschiedene Bedingungen AA6082 Verarbeitung Grenzformänderungsdaten für verschiedene Dehnungswege wurd...

Watch this Scientific Journal Video about A Novel Biaxial Testing Apparatus for the Determination of Forming Limit under Hot Stamping Conditions at JoVE.com

A Novel Biaxial Testing Apparatus for the Determination of Forming Limit under Hot Stamping Conditions

Dieses Protokoll schlägt ein neuartiges System biaxialen Tests auf einen Widerstand verwendet einachsigen Zugversuch Maschine, um Erhitzen der Grenzformänderungsdiagramm (FLD) von Blechen unter Heißprägebedingungen zu bestimmen.

A Novel Biaxial Testvorrichtung für die Bestimmung der Grenzformänderung unter Hot Stamping Bedingungen

The hot stamping and cold die quenching process is increasingly used to form complex shaped structural components of sheet metals. Conventional ...

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7.5K Aufrufe.  Imperial College London.  Dieses Protokoll schlägt ein neuartiges System biaxialen Tests auf einen Widerstand verwendet einachsigen Zugversuch Maschine, um Erhitzen der Grenzformänderungsdiagramm (FLD) von Blechen unter Heißprägebedingungen zu bestimmen. 

Serie: A Novel Biaxial Testing Apparatus for the Determination of Forming Limit under Hot Stamping Conditions

High-pressure, High-temperature Deformation Experiment Using the New Generation Griggs-type Apparatus

In order to address geological processes at great depths, rock deformation should ideally be tested at high pressure (&#62; 0.5 GPa) and high temperature (&#62; 300 &#176;C). However, because of the low stress resolution of current solid-pressure-medium apparatuses, high-resolution measurements are today restricted to low-pressure deformation experiments in the gas-pressure-medium apparatus. A new generation of solid-medium piston-cylinder (&#34;Griggs-type&#34;) apparatus is here described. Able to perform high-pressure deformation experiments up to 5 GPa and designed to adapt an internal load cell, such a new apparatus offers the potential to establish a technological basis for high-pressure rheology. This paper provides video-based detailed documentation of the procedure (using the &#34;conventional&#34; solid-salt assembly) to perform high-pressure, high-temperature experiments with the newly designed Griggs-type apparatus. A representative result of a Carrara marble sample deformed at 700 &#176;C, 1.5 GPa and 10-5 s-1 with the new press is also given. The related stress-time curve illustrates all steps of a Griggs-type experiment, from increasing pressure and temperature to sample quenching when deformation is stopped. Together with future developments, the critical steps and limitations of the Griggs apparatus are then discussed.

Rock deformation needs to be quantified at high pressure. A description of the procedure to perform deformation experiments in a newly designed solid-medium Griggs-type apparatus is here given. This provides technological basis for future rheological studies at pressures up to 5 GPa.

Hochdruck- und Hochtemperatur-Verformung Experiment mit der neuen Generation Griggs-Typ Apparat

In order to address geological processes at great depths, rock deformation should ideally be tested at high pressure (&#62; 0.5 GPa) and high temperature ...

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Umwelt

Experimental Methods for Investigation of Shape Memory Based Elastocaloric Cooling Processes and Model Validation

Shape Memory Alloys (SMA) using elastocaloric cooling processes have the potential to be an environmentally friendly alternative to the conventional vapor compression based cooling process. Nickel-Titanium (Ni-Ti) based alloy systems, especially, show large elastocaloric effects. Furthermore, exhibit large latent heats which is a necessary material property for the development of an efficient solid-state based cooling process. A scientific test rig has been designed to investigate these processes and the elastocaloric effects in SMAs. The realized test rig enables independent control of an SMA&#39;s mechanical loading and unloading cycles, as well as conductive heat transfer between SMA cooling elements and a heat source/sink. The test rig is equipped with a comprehensive monitoring system capable of synchronized measurements of mechanical and thermal parameters. In addition to determining the process-dependent mechanical work, the system also enables measurement of thermal caloric aspects of the elastocaloric cooling effect through use of a high-performance infrared camera. This combination is of particular interest, because it allows illustrations of localization and rate effects &#8212; both important for efficient heat transfer from the medium to be cooled.
The work presented describes an experimental method to identify elastocaloric material properties in different materials and sample geometries. Furthermore, the test rig is used to investigate different cooling process variations. The introduced analysis methods enable a differentiated consideration of material, process and related boundary condition influences on the process efficiency. The comparison of the experimental data with the simulation results (of a thermomechanically coupled finite element model) allows for better understanding of the underlying physics of the elastocaloric effect. In addition, the experimental results, as well as the findings based on the simulation results, are used to improve the material properties.

Experimental methods for investigation of solid state cooling processes and characterization of elastocaloric material properties of Shape Memory Alloys (SMA) are presented. A custom-built test rig has been designed for controlling and comprehensive monitoring of elastocaloric cooling processes. Furthermore, it provides a validation platform for thermomechanically coupled modeling approaches.

Experimentelle Methoden zur Untersuchung von Formgedächtnis-Based Elastocaloric Kühlprozesse und Modellvalidierung

Shape Memory Alloys (SMA) using elastocaloric cooling processes have the potential to be an environmentally friendly alternative to the conventional vapor ...

Ingenieurwesen

Knowledge Based Cloud FE Simulation of Sheet Metal Forming Processes

The use of Finite Element (FE) simulation software to adequately predict the outcome of sheet metal forming processes is crucial to enhancing the efficiency and lowering the development time of such processes, whilst reducing costs involved in trial-and-error prototyping. Recent focus on the substitution of steel components with aluminum alloy alternatives in the automotive and aerospace sectors has increased the need to simulate the forming behavior of such alloys for ever more complex component geometries. However these alloys, and in particular their high strength variants, exhibit limited formability at room temperature, and high temperature manufacturing technologies have been developed to form them. Consequently, advanced constitutive models are required to reflect the associated temperature and strain rate effects. Simulating such behavior is computationally very expensive using conventional FE simulation techniques.
This paper presents a novel Knowledge Based Cloud FE (KBC-FE) simulation technique that combines advanced material and friction models with conventional FE simulations in an efficient manner thus enhancing the capability of commercial simulation software packages. The application of these methods is demonstrated through two example case studies, namely: the prediction of a material's forming limit under hot stamping conditions, and the tool life prediction under multi-cycle loading conditions.

The following paper presents a novel FE simulation technique (KBC-FE), which reduces computational cost by performing simulations on a cloud computing environment, through the application of individual modules. Moreover, it establishes a seamless collaborative network between world leading scientists, enabling the integration of cutting edge knowledge modules into FE simulations.

Wissensbasierte Wolke FE Simulation von Blechumformprozessen

The use of Finite Element (FE) simulation software to adequately predict the outcome of sheet metal forming processes is crucial to enhancing the ...

Experimental Procedure for Warm Spinning of Cast Aluminum Components

High performance, cast aluminum automotive wheels are increasingly being incrementally formed via flow forming/metal spinning at elevated temperatures to improve material properties. With a wide array of processing parameters which can affect both the shape attained and resulting material properties, this type of processing is notoriously difficult to commission. A simplified, light-duty version of the process has been designed and implemented for full-size automotive wheels. The apparatus is intended to assist in understanding the deformation mechanisms and the material response to this type of processing. An experimental protocol has been developed to prepare for, and subsequently perform forming trials and is described for as-cast A356 wheel blanks. The thermal profile attained, along with instrumentation details are provided. Similitude with full-scale forming operations which impart significantly more deformation at faster rates is discussed.

An experimental protocol for instrumented warm rotary forming of cast aluminum alloys employing a bespoke industrially scaled apparatus is presented. Experimental considerations including thermal and mechanical effects are discussed, as well as similitude with full-scale processing of automotive wheels.

Experimentelles Verfahren für Warm Spinnen von Aluminium-Gussbauteilen

High performance, cast aluminum automotive wheels are increasingly being incrementally formed via flow forming/metal spinning at elevated temperatures to ...

Ultrasonic Fatigue Testing in the Tension-Compression Mode

Ultrasonic fatigue testing is one of a few methods which allow investigating fatigue properties in the ultra-high cycle region. The method is based on exposing the specimen to longitudinal vibrations on its resonance frequency close to 20 kHz. With use of this method, it is possible to significantly decrease the time required for the test, when compared to conventional testing devices usually working at frequencies under 200 Hz. It is also used to simulate loading of material during operation in high speed conditions, such as those experienced by components of jet engines or car turbo pumps. It is necessary to operate only in the high and ultra-high cycle region, due to the possibility of extremely high deformation rates, which can have a significant influence on the test results. Specimen shape and dimensions have to be carefully selected and calculated to fulfill the resonance condition of the ultrasonic system; thus, it is not possible to test the full components or specimens of arbitrary shape. Before each test, it is necessary to harmonize the specimen with the frequency of the ultrasonic system to compensate for deviations of the real shape from the ideal one. It is not possible to run a test until a total fracture of the specimen, since the test is automatically terminated after initiation and propagation of the crack to a certain length, when the stiffness of the system changes enough to shift the system out of the resonance frequency. This manuscript describes the process of evaluation of materials' fatigue properties at high-frequency ultrasonic fatigue loading with use of mechanical resonance at a frequency close to 20 kHz. The protocol includes a detailed description of all steps required for a correct test, including specimen design, stress calculation, harmonizing with the resonance frequency, performing the test, and final static fracture.

A protocol for ultrasonic fatigue testing in the high and ultra-high cycle region in axial tension-compression loading mode.

Ultraschall Ermüdungsprüfung im Zug-Druck-Modus

Ultrasonic fatigue testing is one of a few methods which allow investigating fatigue properties in the ultra-high cycle region. The method is based on ...

Conducting Elevated Temperature Normal and Combined Pressure-Shear Plate Impact Experiments Via a Breech-end Sabot Heater System

A novel approach for conducting normal and/or combined pressure-shear plate impact experiments at test temperatures up to 1000 &#176;C is presented. The method enables elevated temperature plate-impact experiments aimed towards probing dynamic behavior of materials under thermomechanical extremes, while mitigating several special experimental challenges faced while performing similar experiments using the conventional plate impact approach. Custom adaptations are made to the breech-end of a single-stage gas-gun at Case Western Reserve University; these adaptations include a precision-machined extension piece made from SAE 4340 steel, which is strategically designed to mate the existing gun-barrel while providing a high tolerance match to the bore and keyway. The extension piece contains a vertical cylindrical heater-well, which houses a heater assembly. A resistive coil heater-head, capable of reaching temperatures of up 1200 &#176;C, is attached to a vertical stem with axial/rotational degrees of freedoms; this enables thin metal specimens held at the front-end of a heat-resistant sabot to be heated uniformly across the diameter to the desired test temperatures. By heating the flyer plate (in this case, the sample) at the breech-end of the gun-barrel instead of at the target-end, several critical experimental challenges can be averted. These include: 1) severe changes in the alignment of the target plate during heating due to the thermal expansion of the several constituents of the target holder assembly; 2) challenges that arise due to the diagnostics elements, (i.e., polymer holographic gratings, and optical probes) being too close to the heated target assembly; 3) challenges that arise for target plates with an optical window, where crucial tolerances between the sample, bond layer, and window become increasingly difficult to maintain at high temperatures; 4) in the case of combined compression-shear plate impact experiments, the need for high-temperature resistant diffraction gratings for the measurement of transverse particle velocity at the free surface of the target; and 5) limitations imposed on the impact velocity necessary for unambiguous interpretation of the measured free surface velocity versus time profile due to thermal softening and possibly yielding of the bounding target plates.By utilizing the adaptations mentioned above, we present results from a series of reverse geometry normal plate impact experiments on commercial purity aluminum at a range of sample temperatures. These experiments show decreasing particle velocities in the impacted state, which are indicative of material softening (decrease in post-yield flow stress) with increasing sample temperatures.

Here, we present a detailed protocol of a new approach for conducting elevated temperature reverse normal plate impact, and combined pressure-and-shear plate impact. The approach involves the use of a breech-end resistive coil heater to heat a sample held at the front-end of a heat-resistant sabot to the desired temperature.

Durchführung von erhöhter Temperatur Normal und kombinierte Druck-Shear Platte folgen Experimente über eine Verschluss-End Sabot-Heizsystem

A novel approach for conducting normal and/or combined pressure-shear plate impact experiments at test temperatures up to 1000 &#176;C is presented. The ...

Application of Design Aspects in Uniaxial Loading Machine Development

In terms of accurate and precise mechanical testing, machines run the continuum. Whereas commercial platforms offer excellent accuracy, they can be cost-prohibitive, often priced in the $100,000 - $200,000 price range. At the other extreme are stand-alone manual devices that often lack repeatability and accuracy (e.g., a manual crank device). However, if a single use is indicated, it is over-engineering to design and machine something overly elaborate. Nonetheless, there are occasions where machines are designed and built in-house to accomplish a motion not attainable with the existing machines in the laboratory. Described in detail here is one such device. It is a loading platform that enables pure uniaxial loading. Standard loading machines typically are biaxial in that linear loading occurs along the axis and rotary loading occurs about the axis. During testing with these machines, a load is applied to one end of the specimen while the other end remains fixed. These systems are not capable of conducting pure axial testing in which tension/compression is applied equally to the specimen ends. The platform developed in this paper enables the equal and opposite loading of specimens. While it can be used for compression, here the focus is on its use in pure tensile loading. The device incorporates commercial load cells and actuators (movers) and, as is the case with machines built in-house, a frame is machined to hold the commercial parts and fixtures for testing.

Here we present a protocol to develop a pure uniaxial loading machine. Critical design aspects are employed to ensure accurate and reproducible testing results.

Anwendung von Gestaltungsmerkmalen einachsiger Belastung Maschinenentwicklung

In terms of accurate and precise mechanical testing, machines run the continuum. Whereas commercial platforms offer excellent accuracy, they can be ...

Biaxial Mechanical Characterizations of Atrioventricular Heart Valves

Extensive biaxial mechanical testing of the atrioventricular heart valve leaflets can be utilized to derive&#160;optimal parameters used in constitutive models, which provide a mathematical representation of the mechanical function of those structures. This presented biaxial mechanical testing protocol involves (i) tissue acquisition, (ii) the preparation of tissue specimens, (iii) biaxial mechanical testing, and (iv) postprocessing of the acquired data. First, tissue acquisition requires obtaining porcine or ovine hearts from a local Food and Drug Administration-approved abattoir for later dissection to retrieve the valve leaflets. Second, tissue preparation requires using tissue specimen cutters on the leaflet tissue to extract a clear zone for testing. Third, biaxial mechanical testing of the leaflet specimen requires the use of a commercial biaxial mechanical tester, which consists of force-controlled, displacement-controlled, and stress-relaxation testing protocols to characterize the leaflet tissue&#39;s mechanical properties. Finally, post-processing requires the use of data image correlation techniques and force and displacement readings to summarize the tissue&#39;s mechanical behaviors in response to external loading. In general, results from biaxial testing demonstrate that the leaflet tissues yield a nonlinear, anisotropic mechanical response. The presented biaxial testing procedure is advantageous to other methods since the method presented here allows for a more comprehensive characterization of the valve leaflet tissue under one unified testing scheme, as opposed to separate testing protocols on different tissue specimens. The proposed testing method has its limitations in that shear stress is potentially present in the tissue sample. However, any potential shear is presumed negligible.

This protocol involves characterizations of atrioventricular valve leaflets with force-controlled, displacement-controlled, and stress-relaxation biaxial mechanical testing procedures. Results acquired with this protocol can be used for constitutive model development to simulate the mechanical behavior of functioning valves under a finite element simulation framework.

Biaxiale mechanische Charakterisierung von ventrikulären Herzklappen

Extensive biaxial mechanical testing of the atrioventricular heart valve leaflets can be utilized to derive&#160;optimal parameters used in constitutive ...

Biotechnik

Layer Microdissection of Tricuspid Valve Leaflets for Biaxial Mechanical Characterization and Microstructural Quantification

The tricuspid valve (TV) regulates the unidirectional flow of unoxygenated blood from the right atrium to the right ventricle. The TV consists of three leaflets, each with unique mechanical behaviors. These variations among the three TV leaflets can be further understood by examining their four anatomical layers, which are the atrialis (A), spongiosa (S), fibrosa (F), and ventricularis (V). While these layers are present in all three TV leaflets, there are differences in their thicknesses and microstructural constituents that further influence their respective mechanical behaviors. 
This protocol includes four steps to elucidate the layer-specific differences: (i) characterize the mechanical and collagen fiber architectural behaviors of the intact TV leaflet, (ii) separate the composite layers (A/S and F/V) of the TV leaflet, (iii) carry out the same characterizations for the composite layers, and (iv) perform post-hoc histology assessment. This experimental framework uniquely allows the direct comparison of the intact TV tissue to each of its composite layers. As a result, detailed information regarding the microstructure and biomechanical function of the TV leaflets can be collected with this protocol. Such information can potentially be used to develop TV computational models that seek to provide guidance for the clinical treatment of TV disease.

This protocol describes the biaxial mechanical characterization, polarized spatial frequency domain imaging-based collagen quantification, and microdissection of tricuspid valve leaflets. The provided method elucidates how the leaflet layers contribute to the holistic leaflet behaviors.

Schichtmikrodissektion von Trikuspidalklappenblättern zur biaxialen mechanischen Charakterisierung und mikrostrukturellen Quantifizierung

The tricuspid valve (TV) regulates the unidirectional flow of unoxygenated blood from the right atrium to the right ventricle. The TV consists of three ...

Stress-Strain Characteristics of Steels

Source:&#160;Roberto Leon, Department of Civil and Environmental Engineering, Virginia Tech, Blacksburg, VA
The importance of materials to human development is clearly captured by the early classifications of world history into periods such as the Stone Age, Iron Age, and the Bronze Age. The introduction of the Siemens and Bessemer processes to produce steels in the mid-1800s is arguably the single most important development in launching the Industrial Revolution that transformed much of Europe and the USA in the second half of the 19th century from agrarian societies into the urban and mechanized societies of today. Steel, in its almost infinite variations, is all around us, from our kitchen appliances to cars, to lifelines such as electrical transmission networks and water distribution systems. In this experiment we will look at the stress-strain behavior of two types of steel that bound the range usually seen in civil engineering applications - from a very mild, hot rolled steel to a hard, cold rolled one.