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Faser-Kunststoff-Verbunde erfahren aufgrund ihrer guten gewichtsspezifischen mechanischen Kennwerte eine zunehmende Verbreitung in verschiedensten Anwendungsfeldern. Eine Voraussetzung für die Ausnutzung der Leichtbaupotenziale bei gleichzeitiger Begrenzung der Herstellkosten ist jedoch eine werkstoffgerechte Lasteinleitung durch geeignete Verbindungsverfahren. Gegenstand dieser Arbeit ist die Untersuchung eines Ansatzes zur Herstellung von Strukturen aus Faser-Kunststoff-Verbund durch eine getrennte Herstellung von teilausgehärteten Substrukturen mit anschließender Verbindung durch gemeinsame Vollaushärtung. Zur umfassenden Analyse der Prozessfenster und Potenziale werden zunächst am Beispiel eines faserverstärkten Werkstoffes auf Epoxidharzbasis die wichtigsten Zustands- und Eigenschaftsänderungen während der Vernetzung des Matrixharzes charakterisiert. Als Resultat dieser Analysen können die Entwicklung des Aushärtegrads bei verschiedener Temperaturführung im Aushärteprozess sowie die grundlegenden mechanischen Eigenschaften von Matrixwerkstoff und Verbund bei verschiedenen Aushärtegraden quantifiziert werden. Aufbauend auf diesen Ergebnissen werden anhand experimenteller Untersuchungen an durch gemeinsame Aushärtung hergestellten Laminaten die Verbindungseigenschaften in Abhängigkeit von unterschiedlichen Einflussfaktoren ermittelt. Für die zwei Prozessvarianten Autoklavprozess und Resin Transfer Molding (RTM) wird die Energiefreisetzungsrate unter Mode I-Belastung bei Variation des Aushärtegrads der zu verbindenden Laminate analysiert. Die Variation der Verbindungseigenschaften wird anhand von rasterelektronenmikroskopischen Untersuchungen der Bruchfläche erklärt. Weiterhin wird der Einfluss der Oberflächeneigenschaften durch Anwendung verschiedener Vorbehandlungen analysiert. Die Oberflächeneigenschaften Oberflächenspannung, Topografie und chemische Zusammensetzung werden gemessen und hinsichtlich ihrer Prognosefähigkeit für die Verbindungseigenschaften diskutiert. Zur Demonstration der Umsetzbarkeit der Herstellmethode auf Bauteilebene werden für den Einsatz im Luftfahrtbereich typische Details hergestellt und mechanisch geprüft. Die Eigenschaften der in der hier untersuchten Methodik hergestellten Details zeigen nur geringe Abweichungen im Vergleich zu denen der Referenzmethode. Due to their good weight-specific mechanical properties, usage of fibre-reinforced polymers is increasing in various fields of application. However, a prerequisite for exploiting the potential of lightweight construction while simultaneously limiting manufacturing costs is the appropriate load introduction through suitable joining processes. The subject of this thesis is the investigation of an approach for the manufacture of fiber-reinforced polymer composite structures by separate processing of partially cured substructures with subsequent assembly by joint full curing. For a comprehensive analysis of the process windows and potentials, the most important state and property changes during the cross-linking of the matrix resin are first characterised using the example of a fibre-reinforced material based on epoxy resin. As a result of these analyses, the development of the degree of cure at different temperatures during the curing process as well as the basic mechanical properties of matrix material and composite at different degrees of cure can be quantified. Based on these findings, experimental investigations on laminates produced by joint curing are used to determine the joint properties as a function of different influencing factors. For the two process variants Autoclave Processing and Resin Transfer Molding (RTM), the energy release rate under Mode I loading is analyzed by varying the degree of cure of the laminates prior to joining. The variation of the bonding properties is explained by scanning electron microscopy investigations of the fracture surface. Furthermore, the influence of the surface properties is analysed by applying different pretreatments. The surface properties surface tension, topography and chemical composition are measured and discussed with respect to their predictive power for the joining properties. To demonstrate the feasibility of the manufacturing method on component level, detail specimens typical for aerospace applications are manufactured and mechanically tested. The properties of the specimens produced in the modified co-curing method show only minor deviations compared to those produced using the reference method.

Objectives: This study analyses the perceived relevance of stress-dimensions in work-settings from the differential views of Human Resource Managers (HRM), Occupational Physicians (OP), Primary Care Physicians (PCP) and Psychotherapists (PT) in Germany. Methods: Cross-sectional study design, using a self-report questionnaire. Descriptive measures and explorative bivariate methods were applied for group-comparisons. Results are presented as rankings of perceived importance and as polarity profiles of contrasting views. Results: N = 627 participants completed the questionnaires (HRM: n = 172; OP: n = 133; PCP: n = 136; PT: n = 186). The stress dimensions with the highest mean ratings across all four professions were: ‘social relationships in the work place’ (M = 3.55, SD = 0.62) and ‘superiors´ leadership style’ (M = 3.54, SD = 0.64). Mean ratings of perceived relevance of stress dimensions differed most between HRM and the three medical professions. Conclusions: The perceived importance of work-related stress-dimensions seems to be higher in the medical disciplines (OP, PCP, PT) than in the group from the management sector (HRM). However, no fundamental disagreement on the role of work-related stress-dimensions seems to hinder e.g., intensified efforts of cooperation across sectors in tackling the “stress-pandemic” and improving the (mental) health of employees.

We determine knotting probabilities and typical sizes of knots in double-stranded DNA for chains of up to half a million base pairs with computer simulations of a coarse-grained bead-stick model: Single trefoil knots and composite knots which include at least one trefoil as a prime factor are shown to be common in DNA chains exceeding 250,000 base pairs, assuming physiologically relevant salt conditions. The analysis is motivated by the emergence of DNA nanopore sequencing technology, as knots are a potential cause of erroneous nucleotide reads in nanopore sequencing devices and may severely limit read lengths in the foreseeable future. Even though our coarse-grained model is only based on experimental knotting probabilities of short DNA strands, it reproduces the correct persistence length of DNA. This indicates that knots are not only a fine gauge for structural properties, but a promising tool for the design of polymer models.

Low-alloyed dual-phase steels are widely used for automotive applications. The favorable mechanical properties of this material class are induced by the composite-like microstructure, i.e., strong martensitic inclusions embedded into a ductile ferrite matrix. This work presents a nonlinear two-scale model that is physically-motivated. The model comprises long-range stresses and includes microstructural parameters. It is suitable to predict the mechanical behavior of different dual-phase steels.