The weight saving benefits of carbon fibre composites have been keenly adopted by civil aviation, with over 50% of the weight of modern designs coming from the carbon fibre components. The rapid rise in demand for this new material has led to the development of fully automated manufacturing techniques, improving rate of production and repeatability of manufacture. However, this rapid development, combined with a constant drive for increased rate of manufacture from industry can result in the formation of critical defects in the more complicated structural components. Manufacturing complex aeronautical structures from carbon fibre leads to a number of interesting mechanical problems. Forcing a multi-layered laminate to conform to a curved geometry requires individual layers to move relative to one another in order to relieve various forming-induced stresses. If the layers are constrained the dissipation of these stresses in the form of interply shear is prevented and a wide range of defects can occur, compromising the integrity of the final component. One of the most important of these is fibre wrinkling, which is effectively the buckling of one or more layers within an uncured laminate. This buckle results in a localised change in fibre orientation, which can result in a significant knockdown in part strength. A large amount of research has been conducted on carbon fibre in its cured state, when it exists as elastic fibres in an elastic matrix. Manufacturing occurs when the material is uncured however, with modern processes typically using fibres which are pre-impregnated with resin in order to reduce void content and aid fibre placement. A ply of uncured material therefore consists of stiff elastic fibres suspended in a very weak liquid viscoelastic material, whose properties are hugely influenced by temperature and rate of deformation. This thesis builds a better understanding of the mechanics involved in forming, using a series of characterisation techniques developed drawing from techniques in the literature. Part of the process involves the fitting of a one-dimensional viscoelasto-plastic model to experimental test data in order to represent the material response when shearing two plies about their interface. This model shows the material response to be dominated by the viscoelastic resin at low temperatures, before becoming frictional and fibre dominated at higher temperatures. In terms of optimum formability, a region exists in the transition from the viscous to frictional behaviour at which resistance to forming is minimised. With this data alone, optimum forming parameters such as rate of deformation, pressure and temperature can be suggested based on the material being used, along with design parameters such as stacking sequence. Another important characteristic which must be understood when considering ply wrinkling is the bending stiffness of uncured prepreg, both as a single ply and when combined to form a small laminate. A wrinkle is in effect the buckling of a single or small number of plies within a laminate, therefore by understanding the bending stiffness and process-induced loading we can begin to predict whether or not wrinkles are likely to occur for a particular manufacturing regime. In order to assess bending stiffness, a modified Dynamic Mechanical Analysis process is employed, replacing the standard Engineers Bending Theory calculations with a Timoshenko element to capture the large degree of intraply shear experienced in the bending of uncured prepreg. Finally, a small laminate scale demonstrator is considered in which a 24-ply laminate is consolidated into a female tool in such a way as to induced maximum shear strain between the plies, in order that the optimum forming parameters predicted by the characterisation tests might be validated. A simple energy minimisation model is used to predict the variation in consolidation strain around the part due to resistance to shear, using material parameters from the model describing the inter-ply shear test data. These parameters are also used to inform a novel modelling technique which has been developed parallel to this thesis, which is validated against the experimental results, and shows how the characterisation techniques can be used to advance simulation methods aimed at reducing the development time for new carbon fibre components. This work provides a set of tests and methodologies for the accurate characterisation of the behaviour of uncured carbon fibre during forming. The models developed alongside these tests allow for a detailed interrogation of the results, providing valuable insight into the mechanics behind the observed material behaviour and enabling informed decisions to be made regarding the forming process in order that the occurrence of defects might be minimised. The primary aim has been to provide a set of vital input parameters for novel, complex process modelling techniques under development, which has been achieved and validated experimentally.

Molecular dynamics (MD) simulations are applied to elucidate the anisotropic characteristics in the material responses for crystallographic nickel substrates with (100), (110) and (111) surface orientations during nanoindentation. The strain energy of the substrate exerted by the tip is stored by the formation of the homogeneous nucleation, and is dissipated by the dislocation sliding of the {111} plane. The steep variations of the indentation curve from the local peak to the local minimums are affected by the numbers of slip angle of {111} sliding plane. The pile-up patterns of the three nickel substrates prove that the crystalline nickel materials demonstrate the pile-up phenomenon from nanoindentation on the nanoscale. The three crystallographic nickel substrates exhibit differing amounts of pile-up dislocation spreading at different crystallographic orientations. The effects of surface orientation in material properties of F.C.C. nickel material on the nanoscale are observable through the slip angle numbers of {111} sliding planes which influence hardness values, as well as the cohesive energy of different crystallographic surfaces that indicate Young¡¦s modulus. Furthermore, the multiscale simulations are performed on the (100) monocrystal nickel substrate by using nanoindentation, compensating for MD limitation of a large specimen simulation without significant increase in the size of the problem. This study examines the accuracy of the coupling method for the multiscale model by means of the indentation curve and the deformation profile. Nanoindentation-induced mechanical deformation in GaN thin films prepared by metal-organic chemical-vapor deposition (MOCVD) was investigated using the Berkovich diamond tip in combining with the cross-sectional transmission electron microscopy (XTEM). By using the focused ion beam (FIB) milling to accurately position the cross-section of the indented region, the XTEM results demonstrate that the major plastic deformation was taking place through the propagation of dislocations. The present observations are in support of attributing the pop-ins appeared in the load-displacement curves to the massive dislocation activities occurring underneath the indenter during loading cycle. The absence of indentation-induced new phases might have been due to the stress relaxation via substrate and is also consistent with the fact that no discontinuity was found upon unloading.

Dans le cadre du travail de recherche réalisé dans cette thèse, la réflexion porte sur les caractéristiques qualitatives des normes juridiques sous des dimensions à la fois théorique, pratique et comparée. L’intérêt majeur de ce travail est de s’interroger sur l’appréhension de la notion de qualité, qui intéresse beaucoup la doctrine, et est devenue une préoccupation croissante de nombreux systèmes juridiques alors même que les contours, et même le contenu, de la notion de qualité des normes restent flou. Le souci d’améliorer la qualité de la législation (au sens large du terme) répond à deux problèmes principaux dans la pratique et la théorie : sur le plan pratique, les défauts formels et substantiels de certaines normes les rendent inaptes à l’accomplissement de leur fonction principale, soit la régulation des relations sociales ; sur le plan théorique, l’exigence de bonne qualité des normes est une condition essentielle dans un état de droit qui permet aux citoyens de savoir à quoi s’attendre de leur gouvernement et à faire des investissements en conséquence (principes de prévisibilité et de sécurité juridique). En dehors de ces caractéristiques formelles ont été examinées les caractéristiques matérielles qui jouent un rôle important quant à l’acceptation des normes juridiques par les citoyens. La démarche adoptée dans le présent travail de recherche ne se limite pas à l’étude de l’élaboration d’une norme juridique, mais porte également sur l’exécution, l’interprétation et l’attitude des juges face aux normes. Toutefois, nous avons dépassé les études déjà réalisées, et nous avons examiné aussi la constitution et les actes administratifs / As part of the research work carried out in this thesis, reflection focuses on the qualitative characteristics of legal norms in terms of theoretical, practical and comparative dimensions. The main interest of this work is to question the apprehension of the notion of quality, which is of great interest to doctrine, and has become a growing preoccupation of many legal systems, even though, the contours, and even the content, the notion of quality standards remain unclear. The concern to improve the quality of legislation (in the broad sense of the term) addresses two main problems in practice and theory: in practice, the formal and substantive defects of certain norms render them unfit for the accomplishment of their main function,namely the regulation of social relations; on the theoretical level, the requirement of good quality of laws is an essential condition of the rule of law that allows citizens to know what to expect from their government and to make investments accordingly (principles of predictability and certainty). Apart from these formal characteristics were examined the material characteristics that play an important role in the acceptance of legal norms by the citizens. This implies the requirement of "rationality" and the "justice" in laws. The approach adopted in this research is not limited to the study of the development of a legal norm but also to the execution, interpretation and attitudes of judges in dealing with the legal norms. However, we have gone beyond the studies already carried out, and we have also examined the constitution and the administrative acts

Cement-based composite boards reinforced by organic fiber, commonly known as cement fiber boards are universal and environmental material. Nowadays they are commonly used in construction industry in the form of facade facing for ventilated facades, interior and exterior ceilings or as a lost formwork for the bridge constructions. In these ways of using the cement fiber boards are strained mainly perpendicularly to their median plane. Material characteristics for this kind of strain are declared by the manufacturers. This diploma thesis is focused on ways of using the cement fiber boards reinforced by organic fiber as prefabricated, constructional material for interior staircases. In this case, every segment is strained even in its median plane. This way of strain is atypical and is not declared by the manufacturers in the manufacturer's technical sheets. The main goal of the diploma thesis was to experimentally determine the material characteristics in relation to the possibility of using the cement fiber boards reinforced by organic fiber for the construction of interior stairways. Material characteristics were determined by using Czech technical standards and information from professional literature. Testing tools made by 3D printing were used in the measurements. The possibilities of connecting cement fiber boards by mechanical and glued joint were checked out. The trial “stand” from CLT boards was designed for the real testing of single-arm and double-arm staircases. The outcomes of the experimental measurements confirmed the possibility to use the cement fiber boards for interior stairways. It is necessary to support the design of the staircase by static calculations and to respect the design of the dimensions of the individual segments in the implementation.

Gyroscopes have been used in previous studies to measure the peak angular velocity of the shoe or foot in the frontal plane (evVel). However, it is not clear whether different test conditions (footwear hardness or locomotion speed) can influence the accuracy of evVel. The purpose of the present study was to compare the accuracy of gyroscopes and electrogoniometers when measuring evVel and the time until evVel (t_evVel) in 12 different conditions using a single axis gyroscope attached to the heel cap. Twenty-four recreational runners were instructed to walk and run on a 15-m indoor track at four locomotion speeds (1.5, 2.5, and 3.5 m/s, and individual running speed) and in three footwear conditions (low to high hardness). The gyroscope data and electrogoniometer data were sampled at a rate of 1000 Hz. Comparisons between both measurement devices showed small mean differences up to 49.8 ± 46.9 deg/s for evVel and up to 5.3 ± 3.5 ms for t_evVel. Furthermore, strong relationships between gyroscope and electrogoniometer data were found for evVel as well as for t_evVel for all conditions. It can be concluded that gyroscopes can be used to accurately determine evVel and t_evVel under a variety of conditions.

Für die Handhabung von Textilien mit unterschiedlichen Greifern sind diverse Parameter entscheidend wie Luftdurchlässigkeit, Biegesteifigkeit, Querkompression, Elastizität, Feuchtigkeitsaufnahme usw. Die Simulation von Handhabungsprozessen ist mit Hilfe von mechanischen, termischen, strömungs- oder multiphysikalischen FEM-Verfahren möglich. Diese erfordern jedoch eine vollständige Materialcharakteristik. Diese Arbeit zeigt eine systematisierte Analyse der Daten und einige Probleme bei der klaren Definition und reproduzierbaren Ermittlung, die aus der Biegeweichheit, unklaren Querschnitten der Textilien und einer großen Anzahl frei abstehender Faserende auf der Produktoberfläche resultieren. / For the handling of cloth with different grippers, parameters like air permeability, compressibility, elasticity, moisture absorption, etc. The simulation of handling processes is possible with the aid of mechanical, thermal, flow or multiphysical FEM methods. However, these require complete material characteristics. This work shows a systematised analysis of the data and some problems in the clear definition and reproducible determination resulting from the bending softness, unclear cross-sections of the textiles and a large number of freely protruding fibre ends on the product surface.

The submitted diploma thesis is focused on problematic of a radial expanding of tubes. In the first part of thesis, there is a summary of possible theoretical formulas for determining the stress-strain material parameters for biaxial bulging test of tube by liquid. Also there are showed several options for testing tools used in research abroad. The work also contains technological and control calculations for the selected test sample from the tube of steel 17 240 (1.4301). At the end of thesis, there are key points for tool design and there is also presented the proposed the test tool for a radial expanding of test sample of tube to the free space and with firmly fixed the ends of tube in the tool.

Gyroscopes have been used in previous studies to measure the peak angular velocity of the shoe or foot in the frontal plane (evVel). However, it is not clear whether different test conditions (footwear hardness or locomotion speed) can influence the accuracy of evVel. The purpose of the present study was to compare the accuracy of gyroscopes and electrogoniometers when measuring evVel and the time until evVel (t_evVel) in 12 different conditions using a single axis gyroscope attached to the heel cap. Twenty-four recreational runners were instructed to walk and run on a 15-m indoor track at four locomotion speeds (1.5, 2.5, and 3.5 m/s, and individual running speed) and in three footwear conditions (low to high hardness). The gyroscope data and electrogoniometer data were sampled at a rate of 1000 Hz. Comparisons between both measurement devices showed small mean differences up to 49.8 ± 46.9 deg/s for evVel and up to 5.3 ± 3.5 ms for t_evVel. Furthermore, strong relationships between gyroscope and electrogoniometer data were found for evVel as well as for t_evVel for all conditions. It can be concluded that gyroscopes can be used to accurately determine evVel and t_evVel under a variety of conditions.

Structure-property quantification of an A36 steel alloy was the focus of this study in order to calibrate and validate a plasticity-damage model. The microstructural parameters included grain size, particle size, particle number density, particle nearest neighbor distances, and percent of ferrite and pearlite. The mechanical property data focused on stress-strain behavior under different applied strain rates (0.001/s, 0.1/s, and 1000/s), different temperatures (293 K and 573 K), and different stress states (compression, tension, and torsion). Notch tension tests were also conducted to validate the plasticity-damage model. Also, failure of an A36 I-beam was examined in cyclic loads, and the crack growth rates were quantified in terms of fatigue striation data. Dynamic strain aging was observed in the stress-strain behavior giving rise to an important point that there exists a critical temperature for such behavior.