Complex systems can be divided into simpler substructures. Determining the properties of each subcomponent by experimental procedures is practical and can serve to verify or calibrate finite element models. In this work, an existing model of a wind turbine blade was improved by use of experimental data. Such a blade is a subpart of a complete wind turbine. For calibration purpose, several material tests were made in order to determine the stiffness and mass properties. Later on, vibration tests of the blades were conducted and compared with simulation results of the improved model. Geometry variability within sets of blades was also studied. The blade twist angles and the center of gravity positions were found to vary moderately, which accounts for differences in blades’ dynamic behavior. Correlations between experimental data and analytical model results were very high for the first eight modeshapes. That is, according to the Model Assurance Criterion the calibrated model achieves a high-quality representation of reality. However, torsional modes in the computer model occur at a higher frequency than the experimental ones. Substructuring of the turbine allows the blades to be modeled and validated independently of the other substructures and can later be incorporated into a complete model of the turbine.

When a water soluble granular fertilizer, such as potash, is wetted and then dried during storage and transportation processes, clumps or cakes often form in the material even when the maximum moisture content is less than 1% by mass. In order to avoid or decrease these occurred cakes, it is essential to characterize cake strength and to explore the process of cake formulation or caking through theoretical/numerical analysis. In this thesis, both experimental measurements of cake strength and theoretical/numerical simulations for recrystallization near a contact point are used to investigate the relationship between the caking process and the cake strength for important factors such as initial moisture content and drying time. <p>In this research, a centrifugal loading method has been developed to determine cake strength in a caked ring specimen of potash fertilizer where internal tensile stresses dominate. Research on fracture mechanics states that brittle materials, such as caked potash, fail at randomly positioned fracture surfaces in tension so the centrifuge test method is well suited to provide good data. A two-dimensional plane stress analysis was used to determine the area-averaged tensile stress at the speed of the centrifuge when each specimen fractures. Repeated tests and uncertainty calculations give data with a narrow range of uncertainty. <p>The centrifuge test facility was used for a series of tests in which the initial moisture content, drying time, particle size and chemical composition (i.e. magnesium content) of the samples were varied. For particle sizes in the range from 0.85 to 3.35 mm, experimental data show that the cake strength increased linearly with initial moisture content for each drying method and particle size, and decreased with increasing particle size for each initial moisture content and drying method. As well, it was also found that cake strength will increase essentially linearly with magnesium content from 0.02% to 0.1% for samples with the same initial moisture content, particle size and drying method. All data show that potash samples tend to form a stronger cake with a slower drying process. <p>A theoretical/numerical model is presented in this thesis to simulate ion diffusion and crystallization near one contact point between two potash (KCl) particles during a typical drying process. The effects of three independent factors are investigated: initial moisture content; evaporation rate; and degree of supersaturation on the surface surrounding the contact point. The numerical results show that the mass of crystal deposition near the contact point will increase with increased initial moisture content and decreased evaporation rate. These numerical predictions for recrystallization near the contact point are consistent with the experimental data for the cake strength of test samples of particle beds. With variations in the solid crystal surface degree of supersaturation near the contact point, simulations showed up to 5 times the increase in the crystal mass deposition near the contact point. This prediction of increased roughness is consistent with another experimental investigation which showed that the surface roughness of NaCl and KCl surfaces increased by a factor of five after one wetting and drying process.

Crosslinking soft tissue has become more common in tissue engineering applications, and recent studies have demonstrated that soft tissue mechanical behavior can be directly altered through crosslinking, but increased understanding of how crosslinking affects intervertebral disc mechanical behavior is needed. In vitro testing of bovine disc and motion segments was used to characterize several important aspects of disc behavior in response to crosslinking after both soaking and injection treatment. The first study was a comparison of different crosslinkers to determine the effect on tensile properties of disc tissue. Circumferential specimens were taken from bovine annulus and then soak treated with an optimized crosslinking formulation or sham solution. A non-contacting laser micrometer was used to measure cross sectional area, after which tension testing until failure was performed to determine yield strain, yield stress, ultimate stress, peak modulus, and resilience. The crosslinkers were observed to produce different changes in the properties, with the measured properties generally increasing. The second study used bilateral annular injections to simulate a clinically relevant delivery method. The dose response of the motion segment’s neutral zone stability metrics against injection concentration was mapped. Concentrations of 20 mM and less had no significant effects on the stability metrics. 40mM demonstrated a change in neutral zone stiffness, while at least 80mM was required to significantly affect neutral zone length. Thus, meaningful changes in joint neutral zone stability were demonstrated using clinically relevant injection and chemical formulations. The third study used combinations of biochemical and accelerated mechanical cyclic loading to degrade gelatin and annulus fibrosus specimens with and without genipin treatment. Genipin crosslinking attenuated changes during cyclic loading to specimen geometry and compliance relative to control samples. Full recovery of genipin treated samples appeared to be hampered, at least partially from continued crosslinking during the accelerated testing. The fourth study tested the effect of genipin crosslinking to resist interlamellar shearing of the annulus lamella. Using a recently reported test method that shears adjacent lamella, crosslinked specimens were noted to have significantly higher yield force, peak force, and resilience compared to sham treated controls, supporting the hypothesis that crosslinking would increase the load bearing ability of the interface.

This research focuses on a study of the material parameters of horse hoof. The study of the problem with the factors that affect to the fastening of the shoe is not performed. Three different tests are carried out to obtain the behavior of the horn wall of the horse hoof in different ways, under physiological conditions and variation of hydration level. The first one is a tensile test to obtain both the force/displacement relation and the stress/strain relation and the parameters derived from them. The second is a hardness test to determine how the material resists to several kinds of permanent-shape changes when a force is applied.Finally, a microscopic study is performed to analyze the fracture surface after testing the specimens. A meticulous analysis of the results and a broad comparison with several researches are performed. The end of the thesis work suggests future works needed to solve the problem.

An experimental technique has been presented to probe the mechanical behavior of thin film materials. The method is capable of tensile testing thin films on substrate and free-standing thin film specimens. A mechanical gripper was designed to address the current challenges in gripping thin film specimens. In order to measure the strain field across the gage section, the moire interferometry technique was used and the respective optical setup was designed. A versatile microfabrication process has been developed to fabricate free-standing dog-bone specimens. Aluminum was used as the model material; however, any other metallization material can be integrated in the process. Thin film specimens have been characterized using SEM, AFM, and TEM. A process has been developed to fabrication diffraction gratings on the specimen by FIB milling. Different grating geometries were fabricated and the diffraction efficiency of the gratings was characterized. The structural damage induced by the Ga+ ions during the FIB milling of the specimens was partially characterized using STEM and EDS. In order to extract the strain field information from the moire interferogram data, a numerical postprocessing technique was developed based on continuous wavelet transforms (CWT). The method was applied on simulated uniform and nonuniform strain fields and the wavelet parameters were tuned to achieve the best spatial localization and strain accuracy.

Abstract The purpose of this research is to investigate the influence of Manganese (Mn) on cast aluminum alloys where a substantial amount of Iron (Fe) is included. Ductility and tensile strength need to be improved in recycled aluminum alloys where greater amounts of Fe are found. Fe is a common impurity and is known to be detrimental to mechanical properties and in order to neutralize the effects of Fe; modifiers such as Mn are added. In this investigation, attempts will be carried out aiming to find the optimal amount of Mn. Other related topics that will be discussed are whether there exists a Mn/Fe ratio which clearly modifies the harmful iron- rich phases and improves the properties for a certain alloy or not. Also, will the heat treatment have a significant effect on mechanical properties? These are some of the questions that will be answered in this paper. It is hard to find research articles that focus only on the influence of Mn on the microstructure and mechanical properties of Al-Si cast alloys. Much of the work that is already published concerns only a specific alloy and casting method. In this work three different casting processes, sand-, die- and high pressure die-casting, will be simulated by using gradient solidification equipment. Furthermore, the influence of heat treatment on the mechanical properties will be examined. The results showed that the solidification rate had the biggest impact on the microstructure and mechanical properties of the alloys, where the fastest cooling rate gave the best results. The effect of Mn seems to influence the samples with coarser microstructures significantly where it had time to modify the Iron-rich needles, also called the β-phase. At higher cooling rates the impact of Mn was impeded. It has been observed that a high content of Mn (around 0.6%) needs to be added before the properties start to improve. UTS (Ultimate Tensile Strength) and YS (Yield Strength) are improved while ductility is lowered. Heat treatment did not seem to have any influence on the effects of Mn.

An experimental technique has been presented to probe the mechanical behavior of thin film materials. The method is capable of tensile testing thin films on substrate and free-standing thin film specimens. A mechanical gripper was designed to address the current challenges in gripping thin film specimens. In order to measure the strain field across the gage section, the moire interferometry technique was used and the respective optical setup was designed. A versatile microfabrication process has been developed to fabricate free-standing dog-bone specimens. Aluminum was used as the model material; however, any other metallization material can be integrated in the process. Thin film specimens have been characterized using SEM, AFM, and TEM. A process has been developed to fabrication diffraction gratings on the specimen by FIB milling. Different grating geometries were fabricated and the diffraction efficiency of the gratings was characterized. The structural damage induced by the Ga+ ions during the FIB milling of the specimens was partially characterized using STEM and EDS. In order to extract the strain field information from the moire interferogram data, a numerical postprocessing technique was developed based on continuous wavelet transforms (CWT). The method was applied on simulated uniform and nonuniform strain fields and the wavelet parameters were tuned to achieve the best spatial localization and strain accuracy.

When a water soluble granular fertilizer, such as potash, is wetted and then dried during storage and transportation processes, clumps or cakes often form in the material even when the maximum moisture content is less than 1% by mass. In order to avoid or decrease these occurred cakes, it is essential to characterize cake strength and to explore the process of cake formulation or caking through theoretical/numerical analysis. In this thesis, both experimental measurements of cake strength and theoretical/numerical simulations for recrystallization near a contact point are used to investigate the relationship between the caking process and the cake strength for important factors such as initial moisture content and drying time. <p>In this research, a centrifugal loading method has been developed to determine cake strength in a caked ring specimen of potash fertilizer where internal tensile stresses dominate. Research on fracture mechanics states that brittle materials, such as caked potash, fail at randomly positioned fracture surfaces in tension so the centrifuge test method is well suited to provide good data. A two-dimensional plane stress analysis was used to determine the area-averaged tensile stress at the speed of the centrifuge when each specimen fractures. Repeated tests and uncertainty calculations give data with a narrow range of uncertainty. <p>The centrifuge test facility was used for a series of tests in which the initial moisture content, drying time, particle size and chemical composition (i.e. magnesium content) of the samples were varied. For particle sizes in the range from 0.85 to 3.35 mm, experimental data show that the cake strength increased linearly with initial moisture content for each drying method and particle size, and decreased with increasing particle size for each initial moisture content and drying method. As well, it was also found that cake strength will increase essentially linearly with magnesium content from 0.02% to 0.1% for samples with the same initial moisture content, particle size and drying method. All data show that potash samples tend to form a stronger cake with a slower drying process. <p>A theoretical/numerical model is presented in this thesis to simulate ion diffusion and crystallization near one contact point between two potash (KCl) particles during a typical drying process. The effects of three independent factors are investigated: initial moisture content; evaporation rate; and degree of supersaturation on the surface surrounding the contact point. The numerical results show that the mass of crystal deposition near the contact point will increase with increased initial moisture content and decreased evaporation rate. These numerical predictions for recrystallization near the contact point are consistent with the experimental data for the cake strength of test samples of particle beds. With variations in the solid crystal surface degree of supersaturation near the contact point, simulations showed up to 5 times the increase in the crystal mass deposition near the contact point. This prediction of increased roughness is consistent with another experimental investigation which showed that the surface roughness of NaCl and KCl surfaces increased by a factor of five after one wetting and drying process.

Philipp Hoffmann Untersuchung zur Fixierung von Knorpelgewebe mittels laserinduzierter Koagulation Aus der Chirurgischen Tierklinik der Veterinärmedizinische Fakultät der Universität Leipzig, angefertigt im Forschungszentrum für Medizintechnik und Biotechnologie GmbH, Bad Langensalza Eingereicht im Januar 2012 97 Seiten, 59 Abbildungen, 9 Tabellen, 318 Literaturangaben 10 Seiten Anhang Schlüsselwörter: Laser, Löten, Knorpelgewebe, Zugfestigkeit, thermische Schäden Gelenkerkrankungen zählen zu den häufigsten Ursachen von Bewegungseinschränkungen in der Human- und Veterinärmedizin. Neben der konservativen Therapie gibt es zahlreiche chirurgische Therapieansätze, unter denen die verschiedenen Verfahren der autologen Chondrozytenimplantation (ACI) vermehrt in den Fokus gerückt sind. Als unbefriedigend stellt sich aktuell die Fixierung der Implantate bzw. Transplantate dar. Ziel der vorliegenden Arbeit war es, zunächst in vitro, unter Nutzung von Gelenkknorpelgewebe aus Kadavermaterial (Schwein, Rind), ein Verfahren einzuarbeiten, mit dem es möglich ist, durch laserinduzierte Koagulation eines Lötmittels eine Verbindung zwischen zwei Knorpelfragmenten bei einer möglichst geringen Gewebeschädigung herzustellen. Als Lötmittel war ein geeignetes Chromophoren-Protein-Gemisch (CPG) herzustellen, welches so auf die Wellenlänge des zur Verfügung stehenden Lasers angepasst wurde, dass die Herstellung von Lötverbindungen möglich war. Die mechanische Festigkeit der Lötverbindungen wurde in verschiedenen Studien zur Optimierung der Lötmittelzusammensetzung und der Lasereinstellungen durch die Bestimmung der Zugkraft geprüft. Ebenso wurden Untersuchungen zum Auftreten thermischer Schäden am Gewebe durch das lasergestützte Löten vorgenommen. Ausgehend von der Untersuchung der Absorptionseigenschaften verschiedener Chromophore und Proteine wurden verschiedene, auf die Wellenlänge des Lasers (810 nm Diodenlaser) abgestimmte, CPG unter Verwendung des Farbstoffes Indocyaningrün (ICG), welcher in dem in der Humanmedizin zugelassenen Diagnostikum ICG-Pulsion® (PULSION Medical Systems AG, München) enthalten ist, und bovinem Serumalbumin (BSA) hergestellt. Knorpelgewebe absorbiert die Strahlung des Diodenlasers (810 nm) kaum (μa ≈ 0 bis 0,02 cm-1). Das Lötmittel (ICG + BSA), dessen Absorptionsmaximum mit 790 nm nah an der Emissionswellenlänge des Lasers liegt, absorbiert hingegen in diesem Wellenlängenbereich gut. Dadurch kann eine direkte Schädigung des Knorpelgewebes durch die Absorption der Laserstrahlung vermieden werden. In den Studien wurden drei Lötmittel mit unterschiedlichen Anteilen an ICG (1 %, 0,25 % und 0,025 %) bei einem BSA-Gehalt von 60 % verwendet. Die Lötmittel mit 0,025 % und 0,25 % ICG wurden zur Prüfung der Zugfestigkeit der gelöteten Verbindung in Abhängigkeit von der Leistungsdichte und der Expositionszeit untersucht. Das Lötmittel mit 0,025 % ICG wurde in den Untersuchungen zur Abhängigkeit der Zugfestigkeit von der Tierspezies, der Entnahmestelle des Knorpelgewebes und der Lötmitteldicke genutzt. Einflüsse der Lagerung des Lötmittels und der Anzahl an Lötmittelpunkten auf die Zugfestigkeit wurden mit dem Lötmittel mit 0,25 % ICG untersucht. Zusätzlich war zu prüfen ob durch ein Knorpelgewebefragment hindurch das CPG zu koagulieren ist. Zur Untersuchung thermisch bedingter Schäden wurden zum einen Temperaturmessungen an der Oberfläche des Knorpelgewebes, im Bereich des Lötmittels und in verschiedenen Tiefen unterhalb des Lötmittels durchgeführt. Zum anderen erfolgten histologische Untersuchungen der Knorpelgewebeproben nach Laseranwendung. Es ist möglich, mittels laserinduzierter Koagulation eines CPG eine Verbindung von Knorpelgewebe vom Schwein und Rind herzustellen. Mit Steigerung der Leistungsdichte und Verlängerung der Expositionszeit kommt es zur Erhöhung der Zugfestigkeit. Die Zugfestigkeiten waren bei Koagulation des CPG durch das Knorpelfragment hindurch niedriger als die Zugfestigkeiten mit aufgelegtem Lötmittel. Unter Laseranwendung kommt es zu einem steilen Ansteigen der Temperatur im Lötmittel bis zum Erreichen einer Höchsttemperatur. Die Steilheit des Temperaturanstieges und die sich einstellenden Temperaturen nehmen mit Erhöhung des im Lötmittel enthaltenen ICG-Gehaltes und der am Laser eingestellten Leistung zu. Die Temperaturerhöhung ist jedoch weitgehend auf das Lötmittel und dessen Randbereiche begrenzt. Die histologischen Untersuchungen verdeutlichten, dass die Laserbestrahlung von Knorpelgewebe mittels Diodenlaser (810 nm) nur eine sehr geringe Schädigung verursacht. Unter Verwendung eines Lötmittels kommt es durch die vom Lötmittel absorbierte Energie zu Schäden am umliegenden Knorpelgewebe. Diese Schädigung ist auf Randbereiche des Lötmittels begrenzt und nimmt mit steigender Leistung und Expositionszeit zu. Bei einer Leistungsdichte von (5,09 W/cm2) konnte eine Verbindung zwischen zwei Knorpelfragmenten erzielt werden, die bei einer Zugkraft von 13,3 N/cm2 nachgibt und bei der die Schädigungen des Knorpelgewebes minimal sind. Die vorliegenden Untersuchungen haben gezeigt, dass es möglich ist, Knorpelfragmente mittels laserinduzierter Koagulation eines CPGs miteinander zu fixieren. / Philipp Hoffmann Investigation for the fixation of articular cartilage tissue using laser-induced coagulation From the Large Animal Clinic for Surgery, Faculty of Veterinary Medicine, University of Leipzig, prepared at Research Centre of Medical Technology and Biotechnology GmbH, Bad Langensalza Submitted in January 2012 97 Pages, 59 figures, 9 tables, 318 references, 10 pages appendices Keywords: laser, soldering, cartilage tissue, tensile strength, thermal damage Joint diseases are among the most common causes of restricted movement of patients in the human and veterinary medicine. In addition to the conservative therapy, there are numerous surgical therapies, under which the various methods of autologous chondrocyteimplantation, have moved increasingly into the focus of scientific and clinical interest. As problematic and unsatisfactory is currently the fixation of the implants. The aim of this study was, first in vitro, taking advantage of articular cartilage tissue from cadaver material (pig, cattle) to incorporate a process by which it is possible to produce by laser-induced coagulation of solder a connection between two cartilage fragments with the smallest possible tissue damage. As solder was a suitable chromophore-protein-mixture (CPG) to establish which it was adapted to the wavelength of the laser is available, that the production of solder joints was possible. The mechanical strength of solder joints has been examined in several studies to optimize the laser settings and the solder ingredients by determining the tensile strength. Likewise, studies on the occurrence of thermal damage to the tissues were made by the laser-assisted soldering. Based on the study of the absorption properties of various chromophores and proteins the wavelength of the laser (810 nm diode laser) was tuned, and different CPG using the dye indocyanine green (ICG), which is within the acceptable in human medicine ICG-Pulsion ® (Pulsion Medical Systems AG, Munich) is included, and bovine serum albumin (BSA) were prepared. Articular cartilage tissue absorbs the radiation of the diode laser (810 nm) hardly (uA ≈ 0 to 0.02 cm–1). The solder (ICG + BSA), whose absorption maximum at 790 nm is close to the emission wavelength of the laser is absorbed. This can be avoided direct damage to the cartilage tissue through the absorption of laser radiation. In the studies, three solders were used with different proportions of ICG (1 %, 0.25 % and 0.025 %) at a content of 60 % BSA. The solder with 0.025 % and 0.25 % ICG were studied to test the tensile strength of the soldered connection as a function of power density and exposure time. The solder containing 0.025 % ICG was used in the investigations of the dependence of tensile strength of the animal species, the donor site of the cartilage and the solder thickness. Influences of storage the solder and the number of solder dots on the tensile strength were investigated with the solder with 0.25 % ICG. In addition it was to examine if it is possible to coagulate the CPG through an articular cartilage fragment. To investigate thermally induced damage to temperature measurements were performed on the surface of the cartilage tissue in the area of the solder and at various depths below the solder. Secondly, histological examinations were made of the articular cartilage after laser application. It is possible to produce by laser-induced coagulation of a CPG an articular cartilage bonding of pig and cattle. With increasing power density and lengthening the exposure time leads to the increase in tensile strength. The tensile strengths were measured with coagulation of the CPG passed through the cartilage fragment is lower than the tensile strengths with applied solder. Under laser application leads to a steep rise in temperature in the solder to reach a maximum temperature. The rate of temperature rise increases with increasing the solder contained in ICG content and on the laser power set. The temperature rise is limited largely to the solder and its peripheral areas. The histological examinations showed that the laser irradiation of cartilage tissue using diode laser (810 nm) only a very little damage caused. Using a solder it comes through the energy absorbed by the solder and damage to the surrounding articular cartilage tissue. This damage is limited to border areas and the flux increases with increasing power and exposure time. At a power density of (5.09 W/cm2) was a connection between two cartilage fragments are obtained, which yields at a tensile force of 13.3 N/cm2 and where the damage to the cartilage tissue is minimal. The present studies have shown that it is possible cartilage fragments by laser-inducedcoagulation of a CPG to fix each other.

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