In this study, the dissimilar metals 5754 aluminum and DP980 ultra-high strength steel were joined using the friction bit joining (FBJ) process. The friction bits were made using one of three steels: 4140, 4340, or H13. Experiments were performed in lap shear, T-peel, and cross tension configurations, with the 0.070" thick 5754 aluminum alloy as the top layer through which the friction bit cut, and the 0.065" thick DP980 as the bottom layer to which the friction bit welded. All experiments were performed using a computer controlled welding machine that was purpose-built and provided by MegaStir Technologies. Through a series of designed experiments (DOE), weld processing parameters were varied and controlled to determine which parameters had a significant effect on weld strength at a 95% confidence level. The parameters that were varied included spindle rotational speeds, Z-command depths, Z-velocity plunge rates, dwell times, and friction bit geometry. Maximum lap shear weld strengths were calculated to be 1425.4lbf and were to be obtained using a bit tip length at 0.175", tip diameter at 0.245", neck diameter at 0.198", cutting and welding z-velocities at 2.6"/min, cutting and welding RPMs at 550 and 2160 respectively, cutting and welding z-commands at -0.07" and -0.12" respectively, cooling dwell at 500 ms, and welding dwell at 1133.8 ms. These parameters were further refined to reduce the weld creation time to 1.66 seconds. These parameters also worked well in conjunction with an adhesive to form weld bonded samples. The uncured adhesive had no effect on the lap shear strengths of the samples. Using the parameters described above, it was discovered that cross tension and T-peel samples suffered from shearing within the bit that caused the samples to break underneath the flange of the bit during testing. Visual inspection of sectioned welds indicated the presence of cracking and void zones within the bit.

yes / This paper presents the results of a numerical investigation on strategies for enhancing the fire behaviour of concrete-filled steel tubular (CFST) columns by using inner steel profiles such as circular hollow sections (CHS), HEB profiles or embedded steel core profiles. A three-dimensional finite element model is developed for that purpose, which is capable for representing the various types of sections studied and the nonlinear behaviour of the materials at elevated temperatures. High strength steel is considered in the numerical model, as a possible way to lengthen the fire endurance. The numerical model is validated against experimental results available in the literature for various types of steel-concrete composite sections using inner steel profiles, obtaining satisfactory results. Based on the developed numerical model, parametric studies are conducted for investigating the influence of the cross-sectional geometry and the steel grade of the inner profiles on the fire performance of these composite columns, for eventually providing some practical recommendations.

In this work, Slow Strain Rate Test (SSRT) testing, Light Optical Microscopy (LOM) and Scanning Electron Microscopy (SEM) were used to study the effect of microstructure, corrosive environments and cathodic polarisation on stress corrosion cracking (SCC) of two grades of high strength steels, Type A and Type B. Type A is manufactured by quench and tempered (Q&T) method. Type B, a normalize steel was used as reference. This study also supports electrochemical polarisation resistance method as an effective testing technique for measuring the uniform corrosion rate. SSRT samples were chosen from base metal, weld metal and Heat Affected Zone (HAZ). SSRT tests were performed at room temperature under Open Circuit Potential (OCP) and cathodic polarisation using 4 mA/cm2 in 1 wt% and 3.5 wt% NaCl solutions. From the obtained corrosion rate measurements performed in 1 wt% and 3.5 wt% NaCl solutions it was observed that increased chloride concentration and dissolved oxygen content enhanced the uniform corrosion for all tested materials. Moreover, the obtained results from SSRT tests demonstrate that both Q&T and normalized steels were not susceptible to SCC in certain strain rate (1×10-6 s-1) in 1 wt% and 3.5 wt% NaCl solutions under OCP condition. It was confirmed by a ductile fracture mode and high reduction in area. The weld metal of Type A with acicular ferrite (AF), pro-eutectoid (PF) and bainite microstructure showed higher susceptibility to hydrogen assisted stress corrosion cracking compared to base metal and HAZ. In addition, typical brittle intergranular cracking with small reduction in area was observed on the fracture surface of the Type A due to hydrogen charging.

Legislative and market pressures are pushing automakers to achieve new fuel economy requirements in the coming years. To help achieve these goals automakers are reducing the overall weight of the vehicle by increasing the use of high-strength aluminum and advanced high-strength steels, and with this increased use comes the desire to quickly, and securely, join these materials within the vehicle. Friction bit joining is a process that lends itself well to joining these materials. This process uses consumable fasteners that need to be used in an automated production line. The geometry of these fasteners causes two main problems: the bits have a short longitudinal axis, which makes them difficult to orient, and the welding platform may be used at different angles; requiring a robust reloading system that is indifferent to its orientation.Our research explored ways that these short axis FBJ fasteners could be handled and transported using various automated methods. We tested the use of small mechanical carriages and magnetic tracks to test their viability for transporting FBJ fasteners. The two different types of fasteners that were used in the project are described. Blow feed tubes ended up being a reliable method of transportation given that the fastener has suitable geometry. The superior bit and feed system design were bench tested using a manually controlled feed system. The system was tested in various orientations to test the robustness of the system since the system was designed to be part of the end effector on a production line robot. The testing revealed that the feed tube is a reliable method of bit transportation and mechanical jaws are a suitable solution for FBJ fastener manipulation. These jaws have several key design features that dramatically increase their effectiveness. Suggestions for future work would be an optimized feed tube cross section, improved material properties in the bit jaw, and more air flow at a higher pressure through the feed tube.

Im Vergleich zu Stahlseilen haben hochfeste Faserseile vorteilhafte Eigenschaften. Insbesondere die bei gleicher Bruchlast um den Faktor 7 bis 10 reduzierte Eigenmasse ermöglicht neue Anwendungen. Die Nachteile von hochfesten Faserseilen gegenüber Stahlseilen , wie beispielsweise Druckempfindlichkeit und Empfindlichkeit gegenüber Wärmeeintrag , behindern den Einsatz von hochfesten Faserseilen in zahlreichen Anwendungsgebieten. Mit der vorliegenden Arbeit soll dieses Problem behoben werden. Dazu wurden die Grundlagen zur Auslegung einer neuen Winde für hochfeste Faserseile , welche die Nachteile dieser Zugmittel kompensiert, erarbeitet. Diese sogenannte Hüllandruckwinde vereint die Eigenschaften von hoher Treibkraft und Seilschonung auf kompaktem Bauraum. Eine Hüllandruckwinde ist eine Treibscheibenwinde, bei der das Seil durch ein umlaufendes, sogenanntes Hüllandruckelement in eine seilschonende Rundrille gedrückt wird. Das Hüllandruckelement kann als Zahnriemen mit Rundrille ausgeführt werden. Sowohl Treibscheibe als auch Hüllandruckelement sind angetrieben. Zur Auslegung von Hüllandruckwinden ist die Kenntnis der Treibkraft und des Systemverhaltens erforderlich. Bei der Überprüfung des Stands der Forschung auf geeignete Treibkraftmodelle stellte sich heraus, dass bislang kein geeignetes Modell existierte. Somit erfolgte die Erarbeitung des sogenannten verallgemeinerten nichtlinearen Modells zur Beschreibung der Treibkraft von Hüllandruckwinden. Dieses wurde validiert und mit einem Benchmark-Modell des Stands der Forschung verglichen. Das verallgemeinerte nichtlineare Modell weist im Vergleich zum Benchmark-Modell für den Zustand Haften einen im Durchschnitt 70 % und für den Zustand Gleiten einen im Durchschnitt 36 % niedrigeren mittleren relativen Fehler auf. Das verallgemeinerte nichtlineare Modell sagt in Bezug zu den Messdaten im Durchschnitt einen um 3,5 % erhöhten Wert vorher. Außerdem wurde das Systemverhalten von Hüllandruckwinden untersucht. Dabei konnte nachgewiesen werden, dass das Verhältnis der Winkelgeschwindigkeiten zwischen Treibscheibe und Hüllandrucklement im Bereich des Umschlingungswinkels des Hüllandruckelements auf dem Seil keinen Einfluss auf die Treibkraft hat. In Verspannversuchen mit einer Last unterhalb der Treibkraft konnten ein um 800 % überhöhtes virtuelles Antriebsdrehmoment des Hüllandruckelements und ein um 538 % überhöhtes Antriebsdrehmoment der Treibscheibe gemessen werden. Als Abhilfemaßnahme für diese überhöhten Antriebsdrehmomente erfolgte die Vorstellung eines lastabhängigen Vorspannmechanismus des Hüllandruckelements, welcher in der Nullserie der Hüllandruckwinde „HERO 1000“ angewendet wird. Aus der Gesamtheit der Erkenntnisse wurden Gestaltungshinweise für Hüllandruckwinden abgeleitet.:Kurzfassung VII Abstract IX 1 Einleitung 11 1.1 Problemstellung und Motivation 11 1.2 Zielsetzung und Forschungsfragen 13 1.3 Aufbau der Arbeit 15 2 Stand der Technik 17 2.1 Definitionen und Erläuterungen 17 2.2 Hochfeste Faserseile 21 2.3 Ablegereife und Zustandsüberwachung 23 2.4 Trommelwinden 25 2.5 Durchlaufwinden 27 2.5.1 Einfach umschlungene Treibscheibenwinden mit glatter Rille 28 2.5.2 Einfach umschlungene Treibscheibenwinden mit profilierten Rillen 30 2.5.3 Mehrfach umschlungene, mehrrillige Treibscheibenwinden 31 2.5.4 Spillwinden 35 2.6 Bandscheibenabzüge 37 3 Stand der Forschung 43 4 Mathematische Modellierung 51 4.1 Betriebssituationen 51 4.2 Vereinfachungen 52 4.3 Festlegungen 55 4.4 Modellierung der Treibkraft 56 4.4.1 Herleitung 56 4.4.2 Lösungen Treibkraftfall C 62 4.4.3 Lösungen Treibkraftfall A 63 4.4.4 Lösungen Treibkraftfall B 64 4.4.5 Lösung Treibscheibenbetrieb ohne HAE 65 4.5 Modellierung der Synchronisation 65 5 Experimentelle Untersuchungen 69 5.1 Versuchsstand 69 5.1.1 Parameter 69 5.1.2 Mechanischer Aufbau 72 5.1.3 Steuerung des Versuchsablaufs 75 5.1.4 Kalibrierung der Frequenzumrichter 76 5.1.5 Erfassung der Messgrößen 78 5.1.6 Auswertung der Messergebnisse 79 5.2 Auswahl der Materialpaarungen 84 5.3 Versuchsplanung 86 5.3.1 Treibkraft 87 5.3.2 Systemverhalten 90 5.4 Versuchsdurchführung 91 5.4.1 Treibkraft 91 5.4.2 Systemverhalten 95 6 Diskussion der Ergebnisse 97 6.1 Vorgehensweise 98 6.2 Treibkraft 99 6.2.1 Treibscheibenbetrieb ohne HAE 99 6.2.2 Treibkraftfall A 109 6.2.3 Treibkraftfall B 114 6.2.4 Treibkraftfall C 120 6.2.5 Kritische Betrachtung des Treibkraftmodells 130 6.3 Systemverhalten 132 6.3.1 Verspannversuche 132 6.3.2 Synchronisationsversuche 139 6.3.3 Fazit Systemverhalten 143 6.4 Gestaltungshinweise für HAW 144 7 Zusammenfassung und Ausblick 147 7.1 Zusammenfassung 147 7.2 Ausblick 150 Abkürzungen 153 Symbole 155 Abbildungsverzeichnis 161 Tabellenverzeichnis 165 Literaturverzeichnis 169 Anlagenverzeichnis 182 / Compared to steel ropes, high-strength fibre ropes have advantageous properties. In particular, the reduction in dead weight by a factor of 7 to 10 for the same breaking load makes new applications possible. The disadvantages of high-strength fibre ropes compared to steel ropes, such as pressure sensitivity and sensitivity to heat input, hinder the use of high-strength fibre ropes in numerous areas of application. The present work is intended to eliminate this problem. For this purpose, the basic principles for the development of a new winch for high-strength fibre ropes, which compensates for the disadvantages of high-strength fibre ropes, were worked out. This so-called belt wrap capstan combines the properties of high driving force and rope protection in a compact design. A belt wrap capstan is a traction sheave winch in which the rope is pressed into a round groove by a so-called belt wrap capstan. The enveloping pressure element can be designed as a toothed belt with a round groove. Both the traction sheave and the enveloping pressure element are driven. The design of belt wrap capstans requires knowledge of the driving force and the system behaviour. When reviewing the state of research for suitable driving force models, it was found that no suitable model existed so far. Therefore, a so-called generalised non-linear model was developed to describe the driving force of belt wrap capstans. This was validated and compared with a benchmark model of the state of the art. Compared to the benchmark model, the generalised nonlinear model has a 70 % lower mean relative error for the sticking condition and a 36 % lower mean relative error for the sliding condition. The generalised non-linear model predicts a 3.5 % higher value on average. The system behaviour of belt wrap capstans was also investigated. It was demonstrated that the ratio of angular velocities between the drive sheave and the enveloping pressure element within the wrap angle of the enveloping pressure element on the rope has no influence on the driving force. In tensioning tests with a load below the driving force, an 800 % excessive virtual driving torque of the sheath pressure element and a 538 % excessive driving torque of the traction sheave could be measured. As a remedy for the tensioning, a load-dependent pretensioning mechanism of the belt wrap capstan was presented, which is used in the zero series of the belt wrap capstan 'HERO 1000'. Design recommendations for belt wrap capstans were derived from all the findings.:Kurzfassung VII Abstract IX 1 Einleitung 11 1.1 Problemstellung und Motivation 11 1.2 Zielsetzung und Forschungsfragen 13 1.3 Aufbau der Arbeit 15 2 Stand der Technik 17 2.1 Definitionen und Erläuterungen 17 2.2 Hochfeste Faserseile 21 2.3 Ablegereife und Zustandsüberwachung 23 2.4 Trommelwinden 25 2.5 Durchlaufwinden 27 2.5.1 Einfach umschlungene Treibscheibenwinden mit glatter Rille 28 2.5.2 Einfach umschlungene Treibscheibenwinden mit profilierten Rillen 30 2.5.3 Mehrfach umschlungene, mehrrillige Treibscheibenwinden 31 2.5.4 Spillwinden 35 2.6 Bandscheibenabzüge 37 3 Stand der Forschung 43 4 Mathematische Modellierung 51 4.1 Betriebssituationen 51 4.2 Vereinfachungen 52 4.3 Festlegungen 55 4.4 Modellierung der Treibkraft 56 4.4.1 Herleitung 56 4.4.2 Lösungen Treibkraftfall C 62 4.4.3 Lösungen Treibkraftfall A 63 4.4.4 Lösungen Treibkraftfall B 64 4.4.5 Lösung Treibscheibenbetrieb ohne HAE 65 4.5 Modellierung der Synchronisation 65 5 Experimentelle Untersuchungen 69 5.1 Versuchsstand 69 5.1.1 Parameter 69 5.1.2 Mechanischer Aufbau 72 5.1.3 Steuerung des Versuchsablaufs 75 5.1.4 Kalibrierung der Frequenzumrichter 76 5.1.5 Erfassung der Messgrößen 78 5.1.6 Auswertung der Messergebnisse 79 5.2 Auswahl der Materialpaarungen 84 5.3 Versuchsplanung 86 5.3.1 Treibkraft 87 5.3.2 Systemverhalten 90 5.4 Versuchsdurchführung 91 5.4.1 Treibkraft 91 5.4.2 Systemverhalten 95 6 Diskussion der Ergebnisse 97 6.1 Vorgehensweise 98 6.2 Treibkraft 99 6.2.1 Treibscheibenbetrieb ohne HAE 99 6.2.2 Treibkraftfall A 109 6.2.3 Treibkraftfall B 114 6.2.4 Treibkraftfall C 120 6.2.5 Kritische Betrachtung des Treibkraftmodells 130 6.3 Systemverhalten 132 6.3.1 Verspannversuche 132 6.3.2 Synchronisationsversuche 139 6.3.3 Fazit Systemverhalten 143 6.4 Gestaltungshinweise für HAW 144 7 Zusammenfassung und Ausblick 147 7.1 Zusammenfassung 147 7.2 Ausblick 150 Abkürzungen 153 Symbole 155 Abbildungsverzeichnis 161 Tabellenverzeichnis 165 Literaturverzeichnis 169 Anlagenverzeichnis 182

No description available.

No description available.

No description available.

No description available.

No description available.