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. Preparazione dei campioni <ol><li> Macchina piatto osso di cane e campioni croce da lega di alluminio materiale professionale 6082 (AA6082) usando una taglierina laser e un controllo numerico computerizzato (CNC) fresatrice (per prove di formabilità a diversi percorsi deformazione compreso deformazione uniassiale, aereo, e tendendo equi-biassiale stati). </li><li> Misurare lo spessore di ogni campione cruciformi e ogni esemplare di cane-osso con un calibro a corsoio tre volte nella regione strumentazione centrale e calcolare i valori medi. Assicurarsi che lo spessore della sezione di calibro in un campione cruciforme è 0,7 ± 0,05 mm e che lo spessore del provino monoassiale è di 1,5 ± 0,1 mm. </li><li> Vernice spray l&#39;intera superficie superiore di un esemplare croce utilizzando una vernice spray nera resistente alla fiamma (in grado di resistere a temperature fino a 1.093 ° C). Attendere che la vernice si asciuga e poi spruzzare fiamma resistente, i puntini di vernice bianca da condizioni di mercato per creare uno stocasticospruzzatura pattern di essere riconosciuto dal sistema DIC (vedere l&#39;esempio nella figura 1). </li><li> Saldare un paio di termocoppie al centro della superficie posteriore (quella opposta alla superficie dipinta) del campione. Collegare l&#39;altra estremità della termocoppia al sistema di controllo della temperatura di retroazione della macchina di prova uniassiale per monitorare e controllare la cronologia variazione di temperatura. </li></ol> 2. Montaggio dell&#39;Apparato biassiale Testing <ol><li> Montare tutte le parti della apparecchiatura di prova biassiale, comprendente una piastra di base, un albero centrale, di ingresso e di uscita piastre girevoli, carrelli, un morsetto, rotaie di guida, e bielle rigide (il dispositivo assemblato è mostrato nella Figura 2). <ol><li> Utilizzando una biella, la coppia piastra girevole ingresso direttamente alla ganascia mobile di una resistenza di riscaldamento uniassiale macchina di trazione, che fornisce la forza di trazione monoassiale. Coppia all&#39;ingresso piastra girevole all&#39;albero motore centrale eCoppia questo albero motore centrale alla piastra girevole uscita. </li><li> Assicurarsi che la rotazione della piastra girevole ingresso intorno all&#39;asse di rotazione fa ruotare l&#39;albero motore, facendo così ruotare la piastra girevole uscita a cui è accoppiato attorno all&#39;asse di rotazione. </li><li> Ad un&#39;estremità, coppia ciascuna delle bielle rigide a uno dei punti di connessione sulla piastra girevole uscita. Coppia l&#39;altra estremità a una delle carrozze. NOTA: Questo farà sì che i carrelli con portacampioni di scorrere avanti e indietro lungo le guide a basso attrito, che può applicare una forza biassiale al modello a croce. </li><li> Utilizzando bulloni, serrare ciascun braccio del campione croce di un carrello con un portacampione e una piastra superiore. </li></ol></li><li> Impostare prese nella camera della macchina di prova di trazione monoassiale, come mostrato in figura 3 (a). Collegare quattro cavi di saldatura di ciascuna coppia di morsetti, che sono fatti di acciaio inossidabile e rame, faucibusctively, e quindi collegare i cavi di saldatura per l&#39;alimentazione elettrica. NOTA: l&#39;area del conduttore dei cavi di saldatura è di 50 mm 2 e la valutazione attuale è 345 A. <ol><li> Mettere le manopole e il morsetto dell&#39;apparecchio test biassiale nelle due ganasce della macchina di prova di trazione monoassiale e serrarli all&#39;interno (figura 3 (a)). </li></ol></li><li> Impostare all&#39;apparecchio di prova biassiale nella camera della macchina di prova di trazione monoassiale, come mostrato in figura 3 (b). <ol><li> Utilizzare due telai ed avvitare le viti sulla parte superiore e il lato inferiore della piastra di base per fissare l&#39;apparecchiatura nella camera della macchina di prova di trazione monoassiale. </li><li> Mettere il campione nel supporto del campione sulla parte superiore del dispositivo di prova biassiale. </li><li> Collegare ogni terminale dei cavi di saldatura a ciascuna regione di bloccaggio del provino. </li></ol></li></ol> 3. Installazione del sistema di riscaldamento e Tempra <ol><li> strettamente connect ciascuna regione di bloccaggio del campione alla piastra superiore acciaio inossidabile, che funge da elettrodo per riscaldamento a resistenza. </li><li> Serrare i cavi di saldatura con terminali ad anello crimp alla piastra superiore di ciascuna regione di bloccaggio. </li><li> Connect svasato ugelli con tubi al sistema di raffreddamento ad alta portata con alimentazione aria regolata a 8.000 kg / m 2 di pressione per il raffreddamento. </li><li> Utilizzare quattro ugelli per soffiare aria dalle braccia del campione alla regione centrale del provino. NOTA: Gli ugelli non sono diretti sulla sezione manometro per il raffreddamento per evitare il blocco della zona centrale dalla vista della telecamera. </li></ol> 4. Configurazione del Sistema DIC <ol><li> Collegare la macchina fotografica ad alta velocità del sistema DIC con un micro lente a un computer. Regolare il frame rate della telecamera a 25 fps, 50 fps e 500 fps dal menu di frame rate (per le prove a tassi di deformazione allungamento di 0,01 / s, 0.1 / s e 1 / s, rispettivamente). Impostare le risoluzioni di tutti imaghi a 1.280 × 1.024 pixel. NOTA: I frame rate dipendono dal numero di punti di dati da raccogliere; almeno 200 punti di dati possono essere raccolti utilizzando le impostazioni sopra. </li><li> Utilizzare un riflettore supplementare con una potenza di 300 W per prove a tassi elevati di deformazione. Puntare il riflettore direttamente nella camera della macchina di prova di trazione monoassiale. </li><li> Regolare la lente telecamera in modo che sia parallela alla superficie superiore del campione nella camera e fuoco la telecamera sulla sezione manometro. </li></ol> 5. Programma Sperimentale <ol><li> Eseguire la resistenza di riscaldamento uniassiale macchina di trazione facendo clic sul pulsante di esecuzione triangolare nel software di controllo. NOTA: elettrica passa attraverso il materiale AA6082 e riscalda alla temperatura soluzione di trattamento termico di 535 ° C 14 ad una velocità di riscaldamento di 30 ° C / s. Il materiale viene mantenuto alla temperatura di 535 ° C per 1 minuto, che è sufficiente per la piena risoluzione di precipitati. Air soffia dal sistema di raffreddamento viene utilizzato per spegnere il materiale ad una velocità di raffreddamento di 15 a uno dei 3 elevate temperature di 100 ° C / s designati nella gamma di 370-510 ° C. </li><li> Allungare il campione con l&#39;apparecchio di prova biassiale ad una velocità di deformazione costante nell&#39;intervallo di 0,01-1 / s e registrare la storia deformazione manualmente premendo il pulsante a scatto collegato alla telecamera ad alta velocità. NOTA: Lo spostamento ingresso dalla macchina di prova uniassiale all&#39;apparecchio di prova biassiale era controllata dal software incorporato della macchina di prova uniassiale. </li><li> Eseguire i test in diversi percorsi di deformazione costituiti uniassiale, deformazione piana e stati sforzare biassiali 3 regolando la configurazione dell&#39;apparecchiatura test biassiale. <ol><li> Scollegare due bielle contrapposte per prove uniassiali. Fissare un campione cane-osso sull&#39;apparato di prova biassiale e collegarlo ai cavi di saldatura, come nei passaggi 3.1-3.4. Ripetere i passaggi 5,1-5,2. </li><li> Fissare due carrelli contrapposti alla piastra di base con bulloni per limitare la deformazione della direzione corrispondente per test in stato di deformazione piana. Bloccare una croce esemplare sull&#39;apparato test biassiale e collegarlo ai cavi di saldatura, come nei passaggi 3,1-3,4. Ripetere i passaggi 5,1-5,2. </li></ol></li><li> Ripetere i punti 5.3.1-5.3.2 per ogni condizione di prova tre volte, utilizzando il nuovo dog-ossa e campioni cruciformi. </li></ol> 6. Elaborazione dati <ol><li> Importare tutte le immagini registrate dalla telecamera ad alta velocità nel software di post-elaborazione e seguire fasi standard per l&#39;analisi dei dati secondo il manuale del software. </li><li> Utilizzare lo standard ISO 3 per determinare i limiti che formano facendo clic sul pulsante Modalità FLC nel software. NOTA: Questo metodo è già stato integrato nel software di elaborazione delle immagini di correlazione. </li><li> Contrassegnare ogni risultato dei limiti di formatura a varie temperatures, velocità di deformazione, e deformazione percorsi in un diagramma. </li><li> Tracciare le curve limite di formatura in tutte le condizioni di prova per ottenere una FLD di una lega in condizioni di stampaggio a caldo. </li></ol>

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The authors have nothing to disclose.

Convenzionali metodi di prova formabilità utilizzati per determinare formare limiti sono generalmente applicabili solo a temperatura ambiente. La tecnica presentata può essere utilizzato per valutare la formabilità di metalli per applicazioni di stampaggio a caldo foglio introducendo un apparecchio di prova biassiale romanzo ad una resistenza di riscaldamento macchina di prova uniassiale. Questo non può essere eseguita con metodi convenzionali per applicazioni di stampaggio a caldo. L&#39;installazione di sistemi di...

L&#39;industria automobilistica sta affrontando una grande sfida globale di riduzione dei consumi e ridurre al minimo l&#39;inquinamento ambientale da emissioni dei veicoli. La riduzione del peso è vantaggioso per migliorare le prestazioni delle automobili e può direttamente ridurre il consumo di energia 1. A causa della bassa formabilità di lamiere a temperatura ambiente, stampa a caldo e processi di tempra stampo freddo (denominato caldo timbratura) 2 sono utilizzati per migliorare la formabilità di leghe e quindi di ottenere componenti di forma complessa in applicazioni automobilistiche. Un diagramma limite di formatura (FLD) è uno strumento utile per valutare la formabilità di una lega 3. Out-of-plane test, come il test Nakazima 4, 5, e nel piano test, come il Marciniak prova 6, 7, 8, unre convenzionali metodi sperimentali per ottenere i Flds di lamiere in varie condizioni 9, 10, 11. Una macchina di prova biassiale servo-idraulico è stato anche utilizzato per studiare la formabilità di leghe a temperatura ambiente 12, 13. Tuttavia, nessuno dei metodi di cui sopra sono applicabili ai test di formabilità in condizioni di stampaggio a caldo, poiché un processo di raffreddamento prima di formare è richiesto con controllo delle velocità di riscaldamento e raffreddamento. La temperatura di deformazione e velocità di deformazione sono difficili da ottenere con precisione. Pertanto, un nuovo sistema di prova formabilità è proposta in questo studio per determinare sperimentalmente i limiti di formatura di lamiere in condizioni di stampaggio a caldo.

<table border="0" cellpadding="0" cellspacing="0" width="923">
	<colgroup>
		<col />
		<col />
		<col />
		<col />
	</colgroup>
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:229px;">Aluminium Alloy&#160;</td>
			<td style="width:152px;">Smiths Metal</td>
			<td style="width:121px;">6082</td>
			<td style="width:421px;">Specimens machining</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:229px;">Laser cutter</td>
			<td style="width:152px;">LVD Ltd</td>
			<td style="width:121px;">HELIUS 25/13</td>
			<td>Laser cutting specimens</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:229px;">CNC machine</td>
			<td style="width:152px;">HAAS Automation</td>
			<td style="width:121px;">TM-2CE</td>
			<td>Machine specimens by milling</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:229px;">Vernier caliper</td>
			<td style="width:152px;">Mitutoyo</td>
			<td style="width:121px;">575-481</td>
			<td>Thickness measurement</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:229px;">Resistance heating uniaxial testing machine</td>
			<td style="width:152px;">Dynamic System Inc</td>
			<td style="width:121px;">Gleeble 3800</td>
			<td>Thermo-mechanical materials simulator</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:229px;">High flow quench system</td>
			<td style="width:152px;">Dynamic System Inc</td>
			<td style="width:121px;">38510</td>
			<td>For air cooling</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:229px;">Thermocouples</td>
			<td style="width:152px;">Dynamic System Inc</td>
			<td style="width:121px;">K type</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:229px;">Nozzles</td>
			<td style="width:152px;">Indexa</td>
			<td style="width:121px;"></td>
			<td>Nozzle flared 1/4 inch bore</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:229px;">Welding cables</td>
			<td style="width:152px;">LAPP Group</td>
			<td style="width:121px;">H01N2-D</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:229px;">High-speed camera</td>
			<td style="width:152px;">Photron</td>
			<td style="width:121px;">UX50</td>
			<td>For DIC testing</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:229px;">Camera lens</td>
			<td style="width:152px;">Nikon</td>
			<td style="width:121px;">Micro 200mm</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:229px;">Lamp</td>
			<td style="width:152px;">Liliput</td>
			<td style="width:121px;">150ce</td>
			<td>300W</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:229px;">Laptop</td>
			<td style="width:152px;">HP</td>
			<td style="width:121px;">Campaq 2530p</td>
			<td>For images recording</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:229px;">Biaxial testing apparatus</td>
			<td style="width:152px;">Manufactured independently</td>
			<td style="width:121px;"></td>
			<td style="width:421px;">All parts were designed and machinced by authors for biaxial testing</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:229px;">Steel&#160;</td>
			<td style="width:152px;">West Yorkshire Steel</td>
			<td style="width:121px;">H13</td>
			<td style="width:421px;">Mateials of the biaxial testing apparatus</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:229px;">Image correlation processing software</td>
			<td style="width:152px;">GOM</td>
			<td style="width:121px;">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

La stampa a caldo e processo di tempra stampo freddo è sempre più utilizzati per formare complessi componenti strutturali sagomati di lamiere. approcci sperimentali convenzionali come out-of-plane e nel piano test, non sono applicabili alla determinazione di formare limiti in riscaldamento e raffreddamento rapido processi vengono introdotti prima di formare per le prove eseguite in condizioni di stampaggio a caldo. Un sistema di test biassiale romanzo in piano è stato progettato e utilizzato per la determinazione di formare limiti di lamiere a vari percorsi di deformazione, la temperatura e velocità di deformazione dopo il riscaldamento e il raffreddamento processi in una resistenza di riscaldamento macchina di prova uniassiale. La parte principale del sistema di prova biassiale è un apparecchio biassiale, che trasferisce una forza uniassiale fornita dalla macchina di prova uniassiale a una forza biassiale. Un tipo di campione cruciforme stato progettato e verificato per la prova formabilità di lega di alluminio 6082 utilizzando il sistema di prova biassiale proposto. L&#39;im digitaleSistema età correlazione (DIC) con una telecamera ad alta velocità è stata utilizzata per misurazioni di deformazione di un campione durante una deformazione. Al fine di proporre questo sistema di prova biassiale è consentire i limiti di formatura di una lega da determinare a diverse temperature e velocità di deformazione in condizioni di stampaggio a caldo.

Poiché Flds sono ceppo altamente dipendente dal percorso, la linearità del percorso di deformazione per ciascuna condizione di prova è stata verificata analizzando i risultati DIC; i percorsi di deformazione sono proporzionali tutta deformazione per ogni condizione di test. L&#39;intervallo del rapporto sforzo minore a maggiore è di circa -0.37 (condizione uniassiale) a 0,26 (condizioni quasi biassiale). Elaborando i dati per le diverse condizioni di AA6082, formando dati limite per ...

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

Questo protocollo propone un sistema di prova biassiale romanzo utilizzato su una resistenza di riscaldamento uniassiale macchina di trazione per determinare lo schema di deformazione (FLD) di lamiere in condizioni di stampaggio a caldo.

Una nuova apparecchiatura biassiale test per la determinazione del limite di formatura in stampa a caldo Condizioni

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 Views.  Imperial College London.  Questo protocollo propone un sistema di prova biassiale romanzo utilizzato su una resistenza di riscaldamento uniassiale macchina di trazione per determinare lo schema di deformazione (FLD) di lamiere in condizioni di stampaggio a caldo. 

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

Fabrication of VB2/Air Cells for Electrochemical Testing

A technique to investigate the properties and performance of new multi-electron metal/air battery systems is proposed and presented. A method for synthesizing nanoscopic VB2 is presented as well as step-by-step procedure for applying a zirconium oxide coating to the VB2 particles for stabilization upon discharge. The process for disassembling existing zinc/air cells is shown, in addition construction of the new working electrode to replace the conventional zinc/air cell anode with a the nanoscopic VB2 anode. Finally, discharge of the completed VB2/air battery is reported. We show that using the zinc/air cell as a test bed is useful to provide a consistent configuration to study the performance of the high-energy high capacity nanoscopic VB2 anode.

Fabrication of VB2/Air Cells for Electrochemical Testing

A protocol is presented to study multi-electron metal/air battery systems by using previous technology developed for the zinc/air cell. Electrochemical testing is then performed on fabricated batteries to evaluate performance.

Fabbricazione di VB<sub&gt; 2</sub&gt; / Air Cells per Elettrochimica Testing

A technique to investigate the properties and performance of new multi-electron metal/air battery systems is proposed and presented. A method for ...

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High-Sensitivity Nuclear Magnetic Resonance at Giga-Pascal Pressures: A New Tool for Probing Electronic and Chemical Properties of Condensed Matter under Extreme Conditions

Nuclear Magnetic Resonance (NMR) is one of the most important techniques for the study of condensed matter systems, their chemical structure, and their electronic properties. The application of high pressure enables one to synthesize new materials, but the response of known materials to high pressure is a very useful tool for studying their electronic structure and developing theories. For example, high-pressure synthesis might be at the origin of life; and understanding the behavior of small molecules under extreme pressure will tell us more about fundamental processes in our universe. It is no wonder that there has always been great interest in having NMR available at high pressures. Unfortunately, the desired pressures are often well into the Giga-Pascal (GPa) range and require special anvil cell devices where only very small, secluded volumes are available. This has restricted the use of NMR almost entirely in the past, and only recently, a new approach to high-sensitivity GPa NMR, which has a resonating micro-coil inside the sample chamber, was put forward. This approach enables us to achieve high sensitivity with experiments that bring the power of NMR to Giga-Pascal pressure condensed matter research. First applications, the detection of a topological electronic transition in ordinary aluminum metal and the closing of the pseudo-gap in high-temperature superconductivity, show the power of such an approach. Meanwhile, the range of achievable pressures was increased tremendously with a new generation of anvil cells (up to 10.1 GPa), that fit standard-bore NMR magnets. This approach might become a new, important tool for the investigation of many condensed matter systems, in chemistry, geochemistry, and in physics, since we can now watch structural changes with the eyes of a very versatile probe.

Nuclear magnetic resonance is one of the most important spectroscopic tools. Here, the development of a new approach under high pressure, currently up to 10.1 GPa, is presented. This opens a new window into condensed matter physics and chemistry, where high-pressure research is of great importance.

Ad alta sensibilità la Risonanza Magnetica Nucleare a Giga-Pascal Pressioni: Un nuovo strumento per Probing proprietà elettroniche e chimiche della Materia Condensata in condizioni estreme

Nuclear Magnetic Resonance (NMR) is one of the most important techniques for the study of condensed matter systems, their chemical structure, and their ...

A Testing Platform for Durability Studies of Polymers and Fiber-reinforced Polymer Composites under Concurrent Hygrothermo-mechanical Stimuli

The durability of polymers and fiber-reinforced polymer composites under service condition is a critical aspect to be addressed for their robust designs and condition-based maintenance. These materials are adopted in a wide range of engineering applications, from aircraft and ship structures, to bridges, wind turbine blades, biomaterials and biomedical implants. Polymers are viscoelastic materials, and their response may be highly nonlinear and thus make it challenging to predict and monitor their in-service performance. The laboratory-scale testing platform presented herein assists the investigation of the influence of concurrent mechanical loadings and environmental conditions on these materials. The platform was designed to be low-cost and user-friendly. Its chemically resistant materials make the platform adaptable to studies of chemical degradation due to in-service exposure to fluids. An example of experiment was conducted at RT on closed-cell polyurethane foam samples loaded with a weight corresponding to ~50% of their ultimate static and dry load. Results show that the testing apparatus is appropriate for these studies. Results also highlight the larger vulnerability of the polymer under concurrent loading, based on the higher mid-point displacements and lower residual failure loads. Recommendations are made for additional improvements to the testing apparatus.

The durability of polymers and fiber-reinforced polymer composites in service is a critical aspect for their designs and condition-based maintenance. We present a novel low-cost laboratory testing platform for the investigation of the influence of concurrent mechanical and environmental loadings, and may help design more efficient yet safer composite structures.

Una piattaforma di prova per una durata Studi di polimeri e fibra-Reinforced Polymer Composites sotto Stimoli Concurrent Hygrothermo-meccanico

The durability of polymers and fiber-reinforced polymer composites under service condition is a critical aspect to be addressed for their robust designs ...

Detection and Recovery of Palladium, Gold and Cobalt Metals from the Urban Mine Using Novel Sensors/Adsorbents Designated with Nanoscale Wagon-wheel-shaped Pores

Developing low-cost, efficient processes for recovering and recycling palladium, gold and cobalt metals from urban mine remains a significant challenge in industrialized countries. Here, the development of optical mesosensors/adsorbents (MSAs) for efficient recognition and selective recovery of Pd(II), Au(III), and Co(II) from urban mine was achieved. A simple, general method for preparing MSAs based on using high-order mesoporous monolithic scaffolds was described. Hierarchical cubic Ia3d wagon-wheel-shaped MSAs were fabricated by anchoring chelating agents (colorants) into three-dimensional pores and micrometric particle surfaces of the mesoporous monolithic scaffolds. Findings show, for the first time, evidence of controlled optical recognition of Pd(II), Au(III), and Co(II) ions and a highly selective system for recovery of Pd(II) ions (up to ~95%) in ores and industrial wastes. Furthermore, the controlled assessment processes described herein involve evaluation of intrinsic properties (e.g., visual signal change, long-term stability, adsorption efficiency, extraordinary sensitivity, selectivity, and reusability); thus, expensive, sophisticated instruments are not required. Results show evidence that MSAs will attract worldwide attention as a promising technological means of recovering and recycling palladium, gold and cobalt metals.

Because of the importance and extensive use of palladium, gold and cobalt metals in high-technology equipment, their recovery and recycling constitute an important industrial challenge. The metal recovery system described herein is a simple, low-cost means for the effective detection, removal, and recovery of these metals from the urban mine.

Rilevamento e recupero di palladio, oro e metalli di cobalto dalla miniera urbana Utilizzando novelli Sensori / Adsorbenti designate con nanoscala Wagon a forma di ruote pori

Developing low-cost, efficient processes for recovering and recycling palladium, gold and cobalt metals from urban mine remains a significant challenge in ...

Development of an Experimental Setup for the Measurement of the Coefficient of Restitution under Vacuum Conditions

The Discrete Element Method is used for the simulation of particulate systems to describe and analyze them, to predict and afterwards optimize their behavior for single stages of a process or even an entire process. For the simulation with occurring particle-particle and particle-wall contacts, the value of the coefficient of restitution is required. It can be determined experimentally. The coefficient of restitution depends on several parameters like the impact velocity. Especially for fine particles the impact velocity depends on the air pressure and under atmospheric pressure high impact velocities cannot be reached. For this, a new experimental setup for free-fall tests under vacuum conditions is developed. The coefficient of restitution is determined with the impact and rebound velocity which are detected by a high-speed camera. To not hinder the view, the vacuum chamber is made of glass. Also a new release mechanism to drop one single particle under vacuum conditions is constructed. Due to that, all properties of the particle can be characterized beforehand.

The coefficient of restitution is a parameter that describes the loss of kinetic energy during collision. Here, a free-fall setup under vacuum conditions is developed to be able to determine the coefficient of restitution parameter for particles in micrometer range with high impact velocities.

Sviluppo di un apparato sperimentale per la misura del coefficiente di restituzione sotto vuoto Condizioni

The Discrete Element Method is used for the simulation of particulate systems to describe and analyze them, to predict and afterwards optimize their ...

Advanced Experimental Methods for Low-temperature Magnetotransport Measurement of Novel Materials

Novel electronic materials are often produced for the first time by synthesis processes that yield bulk crystals (in contrast to single crystal thin film synthesis) for the purpose of exploratory materials research. Certain materials pose a challenge wherein the traditional bulk Hall bar device fabrication method is insufficient to produce a measureable device for sample transport measurement, principally because the single crystal size is too small to attach wire leads to the sample in a Hall bar configuration. This can be, for example, because the first batch of a new material synthesized yields very small single crystals or because flakes of samples of one to very few monolayers are desired. In order to enable rapid characterization of materials that may be carried out in parallel with improvements to their growth methodology, a method of device fabrication for very small samples has been devised to permit the characterization of novel materials as soon as a preliminary batch has been produced. A slight variation of this methodology is applicable to producing devices using exfoliated samples of two-dimensional materials such as graphene, hexagonal boron nitride (hBN), and transition metal dichalcogenides (TMDs), as well as multilayer heterostructures of such materials. Here we present detailed protocols for the experimental device fabrication of fragments and flakes of novel materials with micron-sized dimensions onto substrate and subsequent measurement in a commercial superconducting magnet, dry helium close-cycle cryostat magnetotransport system at temperatures down to 0.300 K and magnetic fields up to 12 T.

We describe the methodology of mechanical exfoliation and deposition of flakes of novel materials with micron-sized dimensions onto substrate, fabrication of experimental device structures for transport experimentation, and the magnetotransport measurement in a dry helium close-cycle cryostat at temperatures down to 0.300 K and magnetic fields up to 12 T.

Metodi sperimentali avanzati per bassa temperatura magnetotrasporto Misura di nuovi materiali

Novel electronic materials are often produced for the first time by synthesis processes that yield bulk crystals (in contrast to single crystal thin film ...

Spark Plasma Sintering Apparatus Used for the Formation of Strontium Titanate Bicrystals

A spark plasma sintering apparatus was used as a novel method for diffusion bonding of two single crystals of strontium titanate to form bicrystals with one twist grain boundary. This apparatus utilizes high uniaxial pressure and a pulsed direct current for rapid consolidation of material. Diffusion bonding of strontium titanate bicrystals without fracture, in a spark plasma sintering apparatus, is possible at high pressures due to the unusual temperature dependent plasticity behavior of strontium titanate. We demonstrate a method for the successful formation of bicrystals at accelerated time scales and lower temperatures in a spark plasma sintering apparatus compared to bicrystals formed by conventional diffusion bonding parameters. Bond quality was verified by scanning electron microscopy. A clean and atomically abrupt interface containing no secondary phases was observed using transmission electron microscopy techniques. Local changes in bonding across the boundary was characterized by simultaneous scanning transmission electron microscopy and spatially resolved electron energy-loss spectroscopy.

A viable technique for the formation of strontium titanate bicrystals at high pressure and fast heating rate via the spark plasma sintering apparatus is developed.

Spark Plasma Sintering apparecchio utilizzato per la formazione di titanato di stronzio Bicrystals

A spark plasma sintering apparatus was used as a novel method for diffusion bonding of two single crystals of strontium titanate to form bicrystals with ...

In Situ Visualization of the Phase Behavior of Oil Samples Under Refinery Process Conditions

To help address production issues in refineries caused by the fouling of process units and lines, we have developed a setup as well as a method to visualize the behavior of petroleum samples under process conditions. The experimental setup relies on a custom-built micro-reactor fitted with a sapphire window at the bottom, which is placed over the objective of an inverted microscope equipped with a cross-polarizer module. Using reflection microscopy enables the visualization of opaque samples, such as petroleum vacuum residues, or asphaltenes. The combination of the sapphire window from the micro-reactor with the cross-polarizer module of the microscope on the light path allows high-contrast imaging of isotropic and anisotropic media. While observations are carried out, the micro-reactor can be heated to the temperature range of cracking reactions (up to 450 &#176;C), can be subjected to H2 pressure relevant to hydroconversion reactions (up to 16 MPa), and can stir the sample by magnetic coupling. 
Observations are typically carried out by taking snapshots of the sample under cross-polarized light at regular time intervals. Image analyses may not only provide information on the temperature, pressure, and reactive conditions yielding phase separation, but may also give an estimate of the evolution of the chemical (absorption/reflection spectra) and physical (refractive index) properties of the sample before the onset of phase separation.

In Situ Visualization of the Phase Behavior of Oil Samples Under Refinery Process Conditions

This article describes a setup and method for the in situ visualization of oil samples under a variety of temperature and pressure conditions that aim to emulate refining and upgrading processes. It is primarily used for studying isotropic and anisotropic media involved in the fouling behavior of petroleum feeds.

In Situ Visualizzazione del comportamento di fase dei campioni di olio Sotto raffineria condizioni di processo

To help address production issues in refineries caused by the fouling of process units and lines, we have developed a setup as well as a method to ...

Subsurface Defect Localization by Structured Heating Using Laser Projected Photothermal Thermography

The presented method is used to locate subsurface defects oriented perpendicularly to the surface. To achieve this, we create destructively interfering thermal wave fields that are disturbed by the defect. This effect is measured and used to locate the defect. We form the destructively interfering wave fields by using a modified projector. The original light engine of the projector is replaced with a fiber-coupled high-power diode laser. Its beam is shaped and aligned to the projector&#39;s spatial light modulator and optimized for optimal optical throughput and homogeneous projection by first characterizing the beam profile, and, second, correcting it mechanically and numerically. A high-performance infrared (IR) camera is set up according to the tight geometrical situation (including corrections of the geometrical image distortions) and the requirement to detect weak temperature oscillations at the sample surface. Data acquisition can be performed once a synchronization between the individual thermal wave field sources, the scanning stage, and the IR camera is established by using a dedicated experimental setup which needs to be tuned to the specific material being investigated. During data post-processing, the relevant information on the presence of a defect below the surface of the sample is extracted. It is retrieved from the oscillating part of the acquired thermal radiation coming from the so-called depletion line of the sample surface. The exact location of the defect is deduced from the analysis of the spatial-temporal shape of these oscillations in a final step. The method is reference-free and very sensitive to changes within the thermal wave field. So far, the method has been tested with steel samples but is applicable to different materials as well, in particular to temperature sensitive materials.

This method aims at locating vertical subsurface defects. Here, we couple a laser with a spatial light modulator and trigger its video input to heat a sample surface deterministically with two anti-phased modulated lines while acquiring highly resolved thermal images. The defect position is retrieved from evaluating thermal wave interference minima.

Localizzazione dei difetti suburfacea mediante riscaldamento strutturato utilizzando la termografia fototermica proiettata laser

The presented method is used to locate subsurface defects oriented perpendicularly to the surface. To achieve this, we create destructively interfering ...

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.

Prova in modalità trazione-compressione ad ultrasuoni di fatica

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 ...