Ingenieurwissenschaften und zugeordnete Tätigkeiten
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Eingeladener Vortrag
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Das Ziel der Arbeit war die Entwicklung einer magnetischen Anreicherungsmethode für eine Bead-basierte Substanzbibliothek zur Identifizierung von Proteinbindern. Im Ramen des Forschungsbelegs wurde bereits eine Anreicherungsmethode für ein Modellsystem einer Peptidbibliothek entwickelt. Das Modellsystem bestand dabei aus zwei verschiedenen Peptiden. Als Positivkontrolle wurde das FLAG-Peptid gewählt, welches selektiv gegen den Anti-FLAG-Antikörper bindet, und ein weiteres Peptid wurde als Negativkontrolle gewählt. Anhand dieses Modellsystems konnte die zuvor entwickelte Anreicherungsmethode von 20.000 auf 1.000.000 Beads vergrößert werden. Hierbei wurde ein Anreicherungsfaktor von 818 und eine gute Wiederfindungsrate von 82% erreicht.
Der Mangel an Anwendungsrichtlinien und Validierungsverfahren für struktur-eingebettete faseroptische Dehnungssensoren, insbesondere auf Faser-Bragg-Gitter (FBG)-Basis, führte bislang dazu, dass diese Sensoren trotz ihrer hervorragenden Eigenschaften im Bereich der kommerziellen Material- und Strukturüberwachung nur in geringem Umfange eingesetzt wurden. Fragen zur Degradation der Sensoren unter Beanspruchung, Alterung durch klimatische Einflüsse und Enthaftung infolge Belastung der Struktur konnten bisher nur theoretisch simuliert oder anhand exemplarischer Proben für einzelne einflussnehmende Parameter im Labor untersucht werden. Die Erfassung des Sensorverhaltens im Bauteil unter komplexen Umwelteinflüssen während des Bauteilbetriebes, um damit eine Aussage zur Zuverlässigkeit der Sensormessdaten zu gewinnen, war bisher nicht möglich.
Im Forschungsprojekt FAMOS² wurde deshalb von 2014 bis 2018 die Realisierung eines Autodiagnoseverfahrens für faseroptische Dehnungssensoren erarbeitet, um die Funktionszuverlässigkeit und Langzeitstabilität der Sensoren während des Bauteilbetriebes innerhalb einer Bauteilstruktur bewerten zu können. Im Rahmen des Forschungsprojektes wurde gezeigt, dass ein FBG-Sensor mit einer speziell angepassten magnetostriktiven Schicht magnetisch so angeregt werden kann, dass mit einer zugeschnittenen Messmethodik zu jedem Zeitpunkt eine Bewertung der Sensorzuverlässigkeit unter Betriebsbedingungen möglich ist. Die auf den Sensor aufgebrachte magnetostriktive Schicht erzeugt bei Anregung mit einem passenden Magnetfeld eine gepulste, synthetische Dehnung. Diese Dehnung steht in einem definierten Verhältnis zum anregenden Magnetfeld und wird optisch über die Verschiebung der Bragg-Wellenlänge ausgelesen. Die Konstanz dieses Verhältnisses stellt dann ein Maß für die korrekte Funktionsfähigkeit des Sensors dar. Das Beschichtungs-verfahren, das magnetische Anregungs- und optische Ausleseverfahren, wie auch die Validierung des Sensors unter Berücksichtigung faseroptischer Effekte wurden während des Projekts konzeptionell entwickelt, aufgebaut und charakterisiert. Qualitativ kann mit diesem Verfahren zunächst eine Gut-/Schlecht-Beurteilung des Sensors vorgenommen werden. Perspektivisch bietet das Verfahren jedoch auch die Möglichkeit, verschiedene Versagensmechanismen bestimmen und klassifizieren zu können. Es zeichnete sich schon während des Projektverlaufs ab, dass sich aus den erzielten Ergebnissen über das Autodiagnoseverfahren hinaus weitere Anwendungsmöglichkeiten für den Einsatz des kombinierten magnetostriktiv-faseroptischen Sensorprinzips, beispielsweise als reiner Magnetfeldsensor, ergeben.
Nach Abschluss dieses Forschungsprojekts besteht nun die Möglichkeit, den Funktionszustand faseroptischer Dehnungssensoren jederzeit unabhängig von Alter, Belastung oder Kenntnis eines Referenzzustands zu einem bestimmten Zeitpunkt bestimmen zu können. Aufbauend auf diesen Ergebnissen können weiterführende Forschungen die Messmethodik vertiefend charakterisieren und weitere Anwendungsfälle erschließen.
Degradation of AISI 630 exposed to CO2-saturated saline aquifer at ambient pressure and 100 bar
(2018)
In general high alloyed steels are suitable as pipe steels for carbon capture and storage technology (CCS), because they provide sufficient resistance against the corrosive environment of CO2-saturated saline aquifer which serves as potential CCS-site in Germany. High alloyed martensitic steel AISI 630 has been proven to be sufficient resistant in corrosive environments, e.g. regarding heat, pressure, salinity of the aquifer, CO2-partial pressure), but reveals a distinct corrosion pattern in CCS environment. Therefore coupons of AISI 630 heat treated using usual protocols were kept at T=60 °C and ambient pressure as well as p=100 bar up to 8000 h in an a) water saturated supercritical CO2 and b) CO2-saturated synthetic aquifer environment similar to on-shore CCS-sites in the Northern German Basin. AISI 630 precipitates a discontinuous ellipsoidal corrosion layer after being exposed for more than 4000 hours. Best corrosion resistance in the CO2-saturated synthetic aquifer environment phase is achieved via normalizing prior to exposure. In water saturated supercritical CO2 tempering at medium temperatures after hardening gives lowest corrosion rates. Corrosion fatigue via push-pull tests with a series of 30 specimens was evaluated at stress amplitudes between 150 MPa and 500 MPa (sinusoidal dynamic test loads, R=-1; resonant frequency ~ 30 Hz). The endurance limit of AISI 630 is reduced by more than 50% when exposed to CCS environment (maximum number of cycles (10 x 106) at a stress amplitude of 150 MPa).
The commercial usage of latent thermal energy storages primarily depends on the development of a suitable phase change material (PCM). For industrial high temperature applications above 400 °C multicomponent chloride eutectics are promising and therefore discussed seriously. The profound thermodynamic investigation of such eutectics requires a much greater amount of specimen material than conventional calorimeter can handle. Therefore, a special adiabatic calorimeter was developed and designed. With a specimen mass of > 100 g the typical thermodynamic measurements with a commercial calorimeter can be extended by cycle stability measurements, which are often decisive for practical application of PCM. Furthermore, by implementing corrosion specimens inside the calorimeter high temperature corrosion experiments according to ISO 21608 can be performed inside the calorimeter. Adiabatic measuring conditions can be provided by using two separate heating systems. Therefore, the outer “protective system” follows the temperature curve of the inner “measuring system” minimizing the temperature difference between the heating systems and simultaneously preventing heat losses from the measuring systems.
Due to rapid, localized heating and cooling, distortions accumulate in additive manufactured laser metal deposition (LMD) components, leading to a loss of dimensional accuracy or even cracking. Numerical welding simulations allow the prediction of these deviations and their optimization before conducting experiments. To assess the viability of the simulation tool for the use in a predictive manner, comprehensive systems as well as to choose the optimal product matches, product analysis methods are needed. Indeed, most of the known methods aim to analyze a product or one product family on the physical level. Different product families, however, may differ largely in terms of the number and nature of components. This fact impedes an efficient comparison and choice of appropriate product family combinations for the production system. A new methodology is proposed to analyze existing products in view of their functional and physical architecture. The aim is to Cluster these products in new assembly oriented product families for the optimization.
The application of implants e.g. for osteosynthesis or substitution of worn out joints is common practice since decades. Successes in surgery and orthopedics are highly dependent on the use of artificial parts for implanting into the human body. Over the years the number of surgical procedures and the number of different implants were growing rapidly. Implants, however, are exposed to complex mechanical, corrosive and tribological loads along with restriction in geometric dimension. While being essentially successful, the sheer number of cases leads to a rising number of implant failures. Such failures are painful for the affected patients and are very costly.
The failure cases presented in this paper occurred from 1981 to 2016. The predominant failure mechanism of all kinds of implants is fatigue fracture. Fatigue cracks are initiated due to a whole bunch of reasons: Material defects and fabrication defects are rare events. The main factors are cyclic overload due to improper fitting with delayed bone healing, corrosion and unauthorized modification of the implant during surgery
The described investigation of carbon-fibre-reinforced plastics (CFRP) documents that damage evolution can be observed by means of X-ray refractography. Comparative investigations with synchrotron technique on CFRP and grey-scale analysis on glass fibre-reinforced-plastics (GFRP) confirm these results. Moreover it was found that the fracture mechanical properties of the matrix system influence damage nucleation and propagation in the laminate during static and fatigue loads. Single-step fatigue tests were carried out on Laminates with RIM135 and LY556 matrix systems made from non-crimped fabric (NCF) or twill weave in different fibre orientations. The damage to the LY556 laminates was characterized by laminate cracks growing rapidly over the whole specimen width, whereas the damage on the RIM135 laminates was characterized by an earlier onset of micro-cracking followed by laminate cracks. The specimens were fatigued up to 108 (very high cycle fatigue (VHCF) regime) load cycles. S-N-curves of damage initiation were drawn and boundaries were identified for endurance within the VHCF regime. A phenomenology based model focusing on matrix stress was applied to reproduce the first inter-fibre failure (IFF) under static and fatigue loads.
The work presents the microstructure, chemical composition and mechanical properties of Inconel 686 coatings after high - temperature corrosion in environment of aggressive gases and ashes. To produce the Ni - based coatings the QS Nd:YAG laser cladding process was carried out. As the substrate used 13CrMo4-5 boilers plate steel. Ni - base alloys characterize the excellent high-temperature corrosion resistance, good strength and ability to work in aggressive environments. Formed clad were characterized by high quality of metallurgical bonding with the substrate material and sufficiently low amount of the iron close to the clad layer surface. After corrosion experiment the oxide scale on the substrate and clad created. The scale on 13CrMo4-5 steel had 70 μm thickness while the scale of the clad had less than 10 μm. The microstructure, chemical composition of the obtained clad and scales were investigated by scanning electron microscope (SEM) and electron probe microanalyzer (EPMA) equipped with the EDS detectors.
Anoxische Objektbehandlungen gegen Schädlingsbefall stellen eine besonders materialverträgliche und umweltschonende Alternative zu chemischen Bekämpfungsverfahren dar. Die Wirksamkeit hängt jedoch von der Dauer, dem Restsauerstoffgehalt sowie der Temperatur und Feuchtigkeit ab. Unterschiedliche Arten von Schadinsekten sind verschieden tolerant gegenüber sauerstoffarmen Bedingungen. Insbesondere bei Behandlungsbedingungen von unter 24° C und mehr als 0,5 % Restsauerstoffgehalt stößt das Verfahren an die Grenze der Zuverlässigkeit. In Versuchsreihen unter standardisierten Bedingungen erwiesen sich insgesamt 12 von 34 im Projekt untersuchte Insektenarten hierbei als widerstandsfähig. Davon als besonders tolerante Arten sind Hylotrupes bajulus, Lasioderma serricorne, Trogoderma parabile und Mezium affine zu nennen.
Mit dem entwickelten UWB-Sensoriksystem können durch elektromagnetische Wellen Bewegungen von Schädlingen innerhalb geschlossener Holzobjekte berührungslos erfasst werden. Voraussetzung für die eindeutige Detektion der Schädlingsaktivität ist neben der digitalen Signalverarbeitung zur Filterung und Extraktion des Nutzsignals, die genügend hohe Eindringtiefe, die ausreichend ist, wenn Schädlingsvorkommen häufig dicht unter der Holzoberfläche gelegen sind. Die Versuchsergebnisse haben gezeigt, dass bereits eine einzelne Trockenholztermite der Art Incisitermes marginipennis hinter einer 5 cm dicken Holzplatte aufgespürt werden kann. Somit erscheint das Messsystem potentiell für die Erfolgskontrolle einer Anoxia-Behandlung an Museumsgütern geeignet.
Our research focused on Inconel 625 weld overlays on 16Mo3 steel boiler pipes. The Investigation focused on the characterization of changes in the microstructure and chemical composition after annealing. The annealing was performed for ten hours at temperatures from 600 to 1000°C. Changes in the microstructure were observed with a scanning and transmission electron microscope (SEM and TEM). The investigation was supplemented by hardness measurements.
This work presents the non-destructive spectroscopic characterisation of original Dead Sea Scrolls (DSS)parchment fragments from Ronald Reed collection. The fragments are of paramount importance becausethey have never been subjected to any treatment of preservation and restoration, this allows to investi-gate the manufacturing method of real original Jewish parchments. The manufacture of “sacred” Jewishparchments, in fact, is traditionally supposed to use a superficial tannin treatment. To study the DSS frag-ments, it was necessary both to analyse mock-up samples, especially manufactured in order to reproduceancient Oriental Jewish ritual parchments, and to compare the results with those obtained in the analysisof modern and ancient Western Jewish ritual parchments, in order to test the effectiveness of the selectedspectroscopic techniques. Traditionally, the main difference between Oriental and Western traditionalparchment preparation consisted in the dehairing method: enzymatic for Oriental and lime-based forWestern. Moreover, a finishing treatment with tannin was supposed to be applied on ritual Jewish parch-ments. The need of reference samples derives from the knowledge that each parchment preparation,treatment and degradation can induce structural modifications that affect the spectral features. FourierTransform Infrared Spectroscopy by Attenuated Total Reflection (ATR-FTIR), FT-Raman and m-Ramanwere used in this study. The experimental results allowed us to recognise, with different sensitivity, thepresence of tannin by using m-Raman and IR spectroscopies and to prove that not all the archaeologicalsamples were manufactured in the same way with vegetal extracts. Many salts (tschermigite, dolomite,calcite, gypsum and iron carbonate) were found on the surface of DSS fragments. They can derive fromthe degradation processes and storage environment before the discovery or from the manufacture. More-over, the different sensitivities and instrumental characteristics of the used techniques permitted us toestablish an analytical protocol, useful for further studies of similar materials.
Der Vortrag gibt den aktuellen Stand der Normung im Bereich der Oberflächen-technik insbesondere der Oberflächenanalytik und der Oberflächenmess- und -prüftechnik wider. Vorgestellt wird der Status technischer Berichte, Normenentwürfe und Normen u.a. zur Charakterisierung von funktionellen Glasoberflächen für bioanalytische Anwendungen, zur Messung der Schichtdicke von Nanomaterialien mittels Ellipsometrie, zur Kalibrierung von Interferometern und Interferenzmikroskopen für die Formmessung, zur Rockwelleindringprüfung zur Bewertung der Schicht-haftung, zu den Grundlagen der Ellipsometrie, zur Messung der Schichtdicke mittels Wirbelstromverfahren, zur Schichtpotentialmessung von Mehrfach-Nickelschichten, zu Filtern und Augenschutzgeräten gegen Laserstrahlung sowie zur Bestimmung der Schichthaftung mittels Zugversuch.
Foreword
(2018)
The subject of this Special Issue is the fracture mechanics-based determination of the fatigue strength of weldments. Except for one, all papers were written in closer or wider relation to a methodology developed within the framework of the German Project cluster IBESS. Some of them provide background or supplementary information needed in that context but which is also relevant in a wider frame of research activities. The acronym IBESS stands for the topic of this Special Issue (in German: „Integrale Methode zu Bruchmechanischen Ermittlung der Schwingfestigkeit von Schweißverbindungen). Eight partners were involved. The cluster was cooperatively founded by the German Research Foundation (Deutsche Forschungsgemeinschaft) and by the German AiF Network (Arbeitsgemeinschaft industrieller Forschungsvereinigungen) for industrial research.
Fiber-reinforced-polymers (FRPs) are in current research focus in the lightweight construction industry, because of their extraordinary characteristics (stiffness and strength-to-density relation). The structure of polymer matrix and the interaction with reinforcement are crucial for optimization of the mechanical and thermal properties of FRPs. Due to the macromolecular chain structure, the mechanical properties of a polymer strongly vary with temperature: Below the glass transition, the chain segments of a polymer are “frozen”. Regarding fracture, the total changed energy during fracture if only dissipates for the generation of the new surfaces. However, in the region of the glass transition, the polymer chain segments start to get “unfrozen”, and the energy is not only required for generating new surfaces, but also for irreversibly deformation. This irreversible deformation is affected by the global temperature and the local temperature near the crack tip, which is affected by the local strain rate and crack propagation velocity.
Hence, in this research project, the irreversible deformation of neat and reinforced polymers will be controlled by changing the global temperature as well as the local temperature. With using different fracture experiments, the amount of energy required for creating new surfaces and for the irreversible deformation will be separated. The fracture tests include the conventional tensile test, the macroscopic peel test and the single fiber peel – off test.
The performance of functional coatings and adhesively joined hybrid components relies strongly on the stability of the polymer-metal interface. With the increasing utilization of multi-material structures in the automotive and aerospace industry, it is of great scientific and technical interest to understand the processes leading to interface degradation and to develop novel strategies to increase corrosion and delamination resistance.
The aim of this project is to develop thin epoxy-based films on aluminium alloy AA2024-T3 as a model system and to investigate their interfacial stability under corrosive and coupled corrosive-mechanical load. Electrochemical and spectroscopic methods were used for the characterisation of the film properties and in situ corrosion experiments were performed by means of AFM. The deformation properties of the aluminium alloy and the model coatings were investigated by means of scanning Kelvin probe force microscopy (SKPFM) utilizing the integrated tensile stage.
The presentation will give a brief overview of the capabilities of the new AFM setup to foster future collaborations and summarize our work on the interface stability of model coatings.
The paper deals with the integration of a light emitting diode (LED) into an additive manufactured metal component. Selective laser melting (SLM) and laser metal deposition (LMD) are used. The material used is the chrome-nickel steel 316L. The basic component is manufactured by means of SLM and consists of a solid body and an area with grid structure. The solid body includes a duct in the shape of a groove with a recess for the positioning of the power cable. The LED is embedded in the grid structure via an inlet from the solid body. In further processing, the groove is filled with LMD. Two strategies with different parameter combinations were investigated. It shows that a high energy input near the power cable leads to its destruction. By using multiple parameter combinations during the manufacturing process, this destruction can be prevented. There was a comparison of both strategies with regard to the necessary number of tracks and duration of welding time.
The paper deals with the integration of a light emitting diode (LED) into an additive manufactured metal component. Selective laser melting (SLM) and laser metal deposition (LMD) are used. The material used is the chrome-nickel steel 316L. The basic component is manufactured by means of SLM and consists of a solid body and an area with grid structure. The solid body includes a duct in the shape of a groove with a recess for the positioning of the power cable. The LED is embedded in the grid structure via an inlet from the solid body. In further processing, the groove is filled with LMD. Two strategies with different parameter combinations were investigated. It shows that a high energy input near the power cable leads to its destruction. By using multiple parameter combinations during the manufacturing process, this destruction can be prevented. There was a comparison of both strategies with regard to the necessary number of tracks and duration of welding time.