The work carried out is based on the thesis properties of clinched joints are determined by the proportions of binding mechanisms form-closure, force-closure and material-closure. To describe the acting binding mechanisms and thus to derive the joint properties, detailed knowledge of the local effect of the individual binding mechanisms is necessary to ensure their targeted adjustment by the joining process. The targeted setting of different proportions of the binding mechanisms is achieved firstly via tool geometry and secondly via surface condition of the joined parts. An introduced form-closure component can be quantified by metallographic cross section with subsequent measurement of the quality-determining parameters such as undercut, penetration depth and neck thickness. To qualify the force-closure component, a torsional load can be applied mechanically at rotationally symmetrical clinch joints. This also allows the influence of different surface conditions on the tribological system to be quantified. Measurement of electrical resistance can reveal the binding mechanisms of force- and material-closure. These investigations are carried out on an aluminum joining part combination of the same type. As a result of these investigations, the clinched joints can be designed according to the load occurring in the later life cycle in the form of an optimum and compromise variant with regard to minimum loads to be transmitted mechanically, electrically with regard to low resistance or manufacturing with minimum energy input.

Punktförmige Verbindungen, wie das Clinchen, bieten vorteilhafte Eigenschaften und werden in zunehmendem Maße in der Dünnblech verarbeitenden Industrie für metallische Verbindungen eingesetzt. Sie spielen gegenwärtig für Metall-Kunststoff-Verbindungen eine untergeordnete beziehungsweise gar keine Rolle. Dies ist wahrscheinlich der Tatsache geschuldet, dass Kunststoffe aufgrund ihrer mechanischen Eigenschaften ungeeignet für das Clinchen scheinen. In der vorliegenden Dissertation werden die Grundlagen für das Clinchen von Metall-Kunststoff-Verbindungen erarbeitet und qualifiziert, so dass es möglich ist, damit eine Verbindung dieser Werkstoffe reproduzierbar herzustellen. Im Speziellen werden Prozessmerkmale und mechanische Verbindungseigenschaften des Clinchens von Metall-Kunststoff-Verbindungen sowie der Feuchtigkeitseinfluss des Kunststofffügepartners und der Einfluss von Wärme vor und/oder nach dem Fügen untersucht. / Because of its advantageous properties there is an extended utilization of point-shaped joints, like the clinching, in the sheet processing industry for metal-metal joints. These joining technologies are not relevant for metal-thermoplastic joints currently. The main reason for this could be the fact that the clinching process seems not to be eligible for thermoplastic materials. In the present thesis the fundamentals for clinching metal to thermoplastics were worked out and qualified. The results allow creating reproducible joints out of these materials. Process features and mechanical properties of clinched metal-thermoplastic joints were investigated. Also the influence of moisture and heat input during and after the clinching process was in focus.

In this paper, a study based on experimental and numerical simulations is performed to analyze fatigue cracks in clinched joints. An experimental investigation is conducted to determine the failure modes of clinched joints under cyclic loading at different load amplitudes with single-lap shear tests. In addition, numerical FEM simulations of clinching process and subsequent shear loading are performed to support the experimental investigations by analyzing the state of stresses at the location of failure. An attempt is made to explain the location of crack initiation in the experiments using evaluation variables such as contact shear stress and maximum principal stress.

Die Mechanische Fügetechnik hat durch den Trend der Mischbauweise sowie schlecht schweißgeeigneter Werkstoffe in den letzten Jahren einen erhöhten Stellenwert erlangt. Aus diesem Grund wird die Weiterentwicklung dieser Verfahrensgruppe stark vorangetrieben. Neben den bekannten Verfahren Blindnieten, Fließformschrauben oder Bördeln wird auch das Durchsetzfügen, welches als Clinchen bekannt ist, in seinen Anwendungsgebieten stetig erweitert. Prozessbedingt ist das Clinchen von schlanken Hohlprofilen nur stark eingeschränkt möglich. Die Verfahrenserweiterung des „Orbitalclinchens“ ermöglicht erstmals, schlanke Hohlprofile mittels Clinchens zu verbinden. In der experimentellen Prozessuntersuchung wurden Mischverbindungen aus Stahl- und Aluminiumrundrohren hergestellt. Weiterhin wurden mit einem nachgelagerten Wärmebehandlungsverfahren Rohrverbindungen aus dem Werkstoff 22MnB5 pressgehärtet. Infolge dessen konnte die Scherzugfestigkeit der Clinchpunkte um bis zu 25 % gesteigert werden. / Mechanical joining technology has gained in importance in recent years due to the trend towards mixing methods and materials, that are poorly suitable for welding. For this reason, the further development of this process group is in focus. In addition to the known methods of blind riveting, flow form screws or flanging, clinching is also constantly expanding in its areas of application. Due to the process, the clinching of slim hollow profiles is only possible to a very limited extent. The extension of the 'orbital clinching' process enables for the first time to connect slim hollow profiles by means of clinching. In the experimental process investigation, mixed connections, were made from steel and aluminum round pipes. In addition, pipe connections made of the material 22MnB5 were press-hardened using a subsequent heat treatment process. As a result, the tensile shear strength of the clinch points could be increased by up to 25 %.

Clinching is a joining process that is becoming more and more important in industry due to the increasing use of multimaterial designs. Despite the already widespread use of the process, there is still a need for research to understand the mechanisms and design of clinched joints. In contrast to the tool parameters, process and material disturbances have not yet been investigated to a relatively large extent. However, these also have a great influence on the properties and applicability of clinching. The effect of process disturbances on the clinched joint are investigated with numerical and experimental methods. The investigated process variations are the history of the sheets using the pre-hardening of the material, different sheet thicknesses, sheet arrangements and punch strokes. For the consideration of the material history, a specimen geometry for pre-stretching specimens in uniaxial tension is used, from which the pre-stretched secondary specimens are taken. A finite element model is set up for the numerical investigations. Suitable clinching tools are selected. With the simulation, selected process influences can be examined. The effort of the numerical investigations is considerably reduced with the help of a statistical experimental design according to Taguchi. To confirm the simulation results, experimental investigations of the clinch point geometry by using micrographs and the shear strength of the clinched joint are performed. The analysis of the influence of difference disturbance factors on the clinching process demonstrate the importance of the holistic view of the clinching process.

Submitted by Caroline Periotto (carol@ufscar.br) on 2016-09-26T18:13:21Z No. of bitstreams: 1 DissMS.pdf: 7587278 bytes, checksum: b78af0b72b6cb2a9f5e605c25bfac1d1 (MD5) / Approved for entry into archive by Marina Freitas (marinapf@ufscar.br) on 2016-09-27T20:12:11Z (GMT) No. of bitstreams: 1 DissMS.pdf: 7587278 bytes, checksum: b78af0b72b6cb2a9f5e605c25bfac1d1 (MD5) / Approved for entry into archive by Marina Freitas (marinapf@ufscar.br) on 2016-09-27T20:12:18Z (GMT) No. of bitstreams: 1 DissMS.pdf: 7587278 bytes, checksum: b78af0b72b6cb2a9f5e605c25bfac1d1 (MD5) / Made available in DSpace on 2016-09-27T20:12:23Z (GMT). No. of bitstreams: 1 DissMS.pdf: 7587278 bytes, checksum: b78af0b72b6cb2a9f5e605c25bfac1d1 (MD5) Previous issue date: 2016-02-29 / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Conselho Nacional de Pesquisa (CNPq) / This master thesis aims to study hybrid joints of polyetherimide (PEI) and aluminum 6082-T6 produced by Friction-based Injection Clinching Joining (FICJ). The influences of the process parameters in the frictional heat and polymer degradation were analyzed through a half factorial design. The degradation of PEI was evaluated by size exclusion chromatography (SEC), differential scanning calorimetry (DSC) and infrared spectroscopy (FTIR). The effect of degradation in the joint microstructure and mechanical properties was also analyzed. The macro and microstructural characteristics were evaluated by optical microscopy and Vickers hardness. The static mechanical properties were determined by lap shear testing and cross tensile testing. It has been shown that the F-ICJ causes degradation through multiple chains scissions. Additionally, a thermomechanically affected zone, with lower hardness, and defects such as pores and weld lines are formed. The mechanical performance, mainly in cross tensile testing, is negatively affected by degradation and presence of defects. These results contribute to the optimization and application of F-ICJ to join hybrid structures. / Nesta dissertação de mestrado fabricou-se juntas híbridas de polieterimida (PEI) e alumínio 6082-T6 por rebitagem por injeção baseada em energia friccional (Friction-based Injection Clinching Joining - F-ICJ). Foi analisada a influência dos parâmetros de processo na geração de calor por fricção e na degradação polimérica através de planejamento de experimentos fatorial fracionário. O nível de degradação do PEI foi avaliado por cromatografia de exclusão por tamanho (SEC), calorimetria exploratória diferencial (DSC) e espectroscopia de infravermelho (FTIR). Estudou-se o efeito da degradação em características macro e microestruturais e nas propriedades mecânicas estáticas das juntas. As características macro e microestruturais foram avaliadas por meio de microscopia ótica e microdureza Vickers. A propriedade mecânica estática foi determinada por ensaio de cisalhamento de juntas sobrepostas e de tração da cabeça do rebite. Mostrou-se que o processo F-ICJ causou degradação por cisão de cadeias múltiplas. Adicionalmente, há criação de uma zona termomecanicamente afetada com menor microdureza e formação de defeitos, como poros e linhas de solda. O desempenho mecânico principalmente, em ensaio de tração da cabeça do rebite é negativamente afetado pela degradação e presença de defeitos. Estes resultados contribuem para a otimização e aplicação da técnica F-ICJ, na união de estruturas híbridas.

Eines der am häufigsten in der Automobilindustrie eingesetzten mechanischen Fügeverfahren ist das Clinchen, auch Durchsetzfügen genannt. Hierbei werden zwei oder mehr sich überlappende Bleche lokal umgeformt, sodass eine form- und kraftschlüssige Verbindung mit matrizenseitiger Überhöhung entsteht. Eine Sonderform des Clinchens ist das Flach-Clinchen zur Herstellung einseitig ebener Clinch-Verbindungen. Mit dem Ziel, die Verfahrensgrenzen des konventionellen Flach-Clinchens zu erweitern, werden im Rahmen der vorliegenden Arbeit zwei neuartige Verfahrensvarianten des Flach-Clinchens entwickelt. Um die Verbindungsfestigkeit der Flach-Clinch-Verbindung zu erhöhen, wird ein zusätzliches Hilfsfügeelement in den Fügepunkt eingebracht. Dies bewirkt zum einen eine Vergrößerung des Hinterschnittes und daraus resultierend eine erhöhte Belastbarkeit gegenüber Kopfzugbeanspruchung. Zum anderen wird der Fügepunkt durch das zusätzliche Material stabilisiert und folglich die Belastbarkeit gegenüber Scherzugbeanspruchung verbessert. Die zweite Verfahrensvariante beinhaltet die Kombination aus Flach-Clinchen und Kleben zum sogenannten Flach-Clinchkleben. Hierbei dient die mechanische Verbindung hauptsächlich als Fixierhilfe bis zur vollständigen Aushärtung des Klebstoffs. Dies ermöglicht eine direkte Weiterverarbeitung des Bauteils nach dem Fügen und somit eine deutliche Verkürzung der Prozesszeiten. Die Entwicklung des Flach-Clinchens mit Hilfsfügeelement und des Flach-Clinchklebens erfolgt ausschließlich mittels numerischer Simulationen. Die hierbei gewonnenen Erkenntnisse werden anschließend experimentell verifiziert und die Verbindungsfestigkeiten der neuentwickelten Verfahrensvarianten bestimmt. / Clinching is one of the most common used mechanical joining processes in automotive industry. Here, two or more overlapping metal sheets are locally formed so that a form- and force-closed joint with diesided protrusion is established. A special type of clinching is the so-called flat-clinching for the production of one-sided planar joints. Within the framework of this thesis, two novel process variants of flat-clinching are developed for enhancing the process limitations of conventional flat-clinching. For increasing the joint strength, a complementary joining element is inserted into the joint. This causes an enlargement of the interlocking, leading to a higher resistance to cross tension loads. Also, the additional material stabilizes the joint and hence improves the resistance to shear load. The second process variant, adhesive flat-clinching, includes the combination of flat-clinching and adhesive bonding. The metal sheets are fixed by flat-clinching and the final joint strength is achieved after the complete curing of the adhesive. This enables a continuous processing of the component and therefore, the process time can be shortened. The development of flat-clinching using complementary joining elements and adhesive flat-clinching is exclusively carried out by using numerical simulation. The knowledge gained from the simulations is subsequently experimentally proven. Also, the joint strength of the novel process variants is experimentally determined.

Punktförmige Verbindungen, wie das Clinchen, bieten vorteilhafte Eigenschaften und werden in zunehmendem Maße in der Dünnblech verarbeitenden Industrie für metallische Verbindungen eingesetzt. Sie spielen gegenwärtig für Metall-Kunststoff-Verbindungen eine untergeordnete beziehungsweise gar keine Rolle. Dies ist wahrscheinlich der Tatsache geschuldet, dass Kunststoffe aufgrund ihrer mechanischen Eigenschaften ungeeignet für das Clinchen scheinen. In der vorliegenden Dissertation werden die Grundlagen für das Clinchen von Metall-Kunststoff-Verbindungen erarbeitet und qualifiziert, so dass es möglich ist, damit eine Verbindung dieser Werkstoffe reproduzierbar herzustellen. Im Speziellen werden Prozessmerkmale und mechanische Verbindungseigenschaften des Clinchens von Metall-Kunststoff-Verbindungen sowie der Feuchtigkeitseinfluss des Kunststofffügepartners und der Einfluss von Wärme vor und/oder nach dem Fügen untersucht. / Because of its advantageous properties there is an extended utilization of point-shaped joints, like the clinching, in the sheet processing industry for metal-metal joints. These joining technologies are not relevant for metal-thermoplastic joints currently. The main reason for this could be the fact that the clinching process seems not to be eligible for thermoplastic materials. In the present thesis the fundamentals for clinching metal to thermoplastics were worked out and qualified. The results allow creating reproducible joints out of these materials. Process features and mechanical properties of clinched metal-thermoplastic joints were investigated. Also the influence of moisture and heat input during and after the clinching process was in focus.

Eines der am häufigsten in der Automobilindustrie eingesetzten mechanischen Fügeverfahren ist das Clinchen, auch Durchsetzfügen genannt. Hierbei werden zwei oder mehr sich überlappende Bleche lokal umgeformt, sodass eine form- und kraftschlüssige Verbindung mit matrizenseitiger Überhöhung entsteht. Eine Sonderform des Clinchens ist das Flach-Clinchen zur Herstellung einseitig ebener Clinch-Verbindungen. Mit dem Ziel, die Verfahrensgrenzen des konventionellen Flach-Clinchens zu erweitern, werden im Rahmen der vorliegenden Arbeit zwei neuartige Verfahrensvarianten des Flach-Clinchens entwickelt. Um die Verbindungsfestigkeit der Flach-Clinch-Verbindung zu erhöhen, wird ein zusätzliches Hilfsfügeelement in den Fügepunkt eingebracht. Dies bewirkt zum einen eine Vergrößerung des Hinterschnittes und daraus resultierend eine erhöhte Belastbarkeit gegenüber Kopfzugbeanspruchung. Zum anderen wird der Fügepunkt durch das zusätzliche Material stabilisiert und folglich die Belastbarkeit gegenüber Scherzugbeanspruchung verbessert. Die zweite Verfahrensvariante beinhaltet die Kombination aus Flach-Clinchen und Kleben zum sogenannten Flach-Clinchkleben. Hierbei dient die mechanische Verbindung hauptsächlich als Fixierhilfe bis zur vollständigen Aushärtung des Klebstoffs. Dies ermöglicht eine direkte Weiterverarbeitung des Bauteils nach dem Fügen und somit eine deutliche Verkürzung der Prozesszeiten. Die Entwicklung des Flach-Clinchens mit Hilfsfügeelement und des Flach-Clinchklebens erfolgt ausschließlich mittels numerischer Simulationen. Die hierbei gewonnenen Erkenntnisse werden anschließend experimentell verifiziert und die Verbindungsfestigkeiten der neuentwickelten Verfahrensvarianten bestimmt. / Clinching is one of the most common used mechanical joining processes in automotive industry. Here, two or more overlapping metal sheets are locally formed so that a form- and force-closed joint with diesided protrusion is established. A special type of clinching is the so-called flat-clinching for the production of one-sided planar joints. Within the framework of this thesis, two novel process variants of flat-clinching are developed for enhancing the process limitations of conventional flat-clinching. For increasing the joint strength, a complementary joining element is inserted into the joint. This causes an enlargement of the interlocking, leading to a higher resistance to cross tension loads. Also, the additional material stabilizes the joint and hence improves the resistance to shear load. The second process variant, adhesive flat-clinching, includes the combination of flat-clinching and adhesive bonding. The metal sheets are fixed by flat-clinching and the final joint strength is achieved after the complete curing of the adhesive. This enables a continuous processing of the component and therefore, the process time can be shortened. The development of flat-clinching using complementary joining elements and adhesive flat-clinching is exclusively carried out by using numerical simulation. The knowledge gained from the simulations is subsequently experimentally proven. Also, the joint strength of the novel process variants is experimentally determined.