No description available.

No description available.

No description available.

The aim of this investigation was to review literature for the most suitable aeroelastic tailoring analysis tools for long slender composite structures, and integrate them into an aeroelastic tailoring process. The JS1C Revelation is a high performance sailplane made from modern composites, mostly carbon fibre. This has the advantage of being more rigid than traditional engineering materials, thereby reducing the effects of the twisting deflections on these long slender structures due to aerodynamic loads. The implementing of aeroelastic tailoring can create bend-twist couples for performance improvements. Composites enable the use of aeroelastic tailoring to improve gliding performance. Flaperon 3 of the JS1C 21 m was used as the design problem for aeroelastic tailoring. Aeroelastic tailoring was done by analysing the flaperon structure at the different layup angles to determine the correct design point to tailor the structure to improve aerodynamic performance at thermalling and cruise, but mostly cruise since it accounts for 70% of the flight time. The composite structure analysis tool has the objective to get results during concept design. This directed the line of research of analysis tools to a solution method of two dimensional cross-section mesh properties projected onto a one dimensional beam. The literature of Hodges had good verification and published data on the analysis tools. The analysis tools comprised of three programs that were not very user friendly. Thus the author compiled a Matlab program as a user interface tool to run the three programs together. The aeroelastic tailoring process systematically works through the known design variables and objectives, which are given as inputs to the analysis tool. The analysis tool plots the coupling data versus layup angle. From this the best layup angles for a sought-after bend-twist couple is used to aeroelastically tailor the wing. The composite structure analysis tool’s accuracy was verified by analysing cantilever beam deflections and comparing the results with hand calculations and SolidWorks Simulation FEM results. The analysis tool’s accuracy was further verified by comparing the aerodynamic torsional load’s twist deflections with thin walled tube theory. The analysis tool was validated by applying a torsional load at the tip of a JS1C production Flaperon 3 in an experimental setup and then comparing this result with the Flaperon 3 modelled in the analysis tool. These comparisons also ensured that the model’s composite material properties and the meshing of the flaperon cross-sectional properties were correct. This aeroelastic tailoring was validated with the advantage of then being used to improve the aerodynamic performance of the JS1C Revelation 21 m tip’s flaperon. This improvement could be made by making use of a tailored bend-twist couple to reduce the effect of the aerodynamic load’s twist deflections. A test sample of the JS1C 21 m flaperon 3 was used to validate aeroelastic tailoring. The test sample was designed to be 1 m in length and have all the specified tailoring coupling characteristics that could improve the aerodynamic performance of the JS1C 21 m flaperon 3. The test sample was manufactured according to Jonker Sailplanes manufacturing standards and experimentally set up with the same applied deflections as in the analysis tool. The calculated bend-twist values and the experimental setup results were similar with a negligible difference, assuming small displacements and an aspect ratio greater than 13; this confirmed that the PreVABS/VABS/GEBT composite structure analysis tool could be used in aeroelastic tailoring to predict and design the bend-twist couple needed to improve the aerodynamic performance of the JS1C 21 m. While the twist behaviour of Flaperon 3 was improved by the tailored bend-twist couple, it was still necessary to add pre-twist as well, to fully address the effects of twisting by aerodynamic forces. / MIng (Mechanical Engineering), North-West University, Potchefstroom Campus, 2014

The aim of this investigation was to review literature for the most suitable aeroelastic tailoring analysis tools for long slender composite structures, and integrate them into an aeroelastic tailoring process. The JS1C Revelation is a high performance sailplane made from modern composites, mostly carbon fibre. This has the advantage of being more rigid than traditional engineering materials, thereby reducing the effects of the twisting deflections on these long slender structures due to aerodynamic loads. The implementing of aeroelastic tailoring can create bend-twist couples for performance improvements. Composites enable the use of aeroelastic tailoring to improve gliding performance. Flaperon 3 of the JS1C 21 m was used as the design problem for aeroelastic tailoring. Aeroelastic tailoring was done by analysing the flaperon structure at the different layup angles to determine the correct design point to tailor the structure to improve aerodynamic performance at thermalling and cruise, but mostly cruise since it accounts for 70% of the flight time. The composite structure analysis tool has the objective to get results during concept design. This directed the line of research of analysis tools to a solution method of two dimensional cross-section mesh properties projected onto a one dimensional beam. The literature of Hodges had good verification and published data on the analysis tools. The analysis tools comprised of three programs that were not very user friendly. Thus the author compiled a Matlab program as a user interface tool to run the three programs together. The aeroelastic tailoring process systematically works through the known design variables and objectives, which are given as inputs to the analysis tool. The analysis tool plots the coupling data versus layup angle. From this the best layup angles for a sought-after bend-twist couple is used to aeroelastically tailor the wing. The composite structure analysis tool’s accuracy was verified by analysing cantilever beam deflections and comparing the results with hand calculations and SolidWorks Simulation FEM results. The analysis tool’s accuracy was further verified by comparing the aerodynamic torsional load’s twist deflections with thin walled tube theory. The analysis tool was validated by applying a torsional load at the tip of a JS1C production Flaperon 3 in an experimental setup and then comparing this result with the Flaperon 3 modelled in the analysis tool. These comparisons also ensured that the model’s composite material properties and the meshing of the flaperon cross-sectional properties were correct. This aeroelastic tailoring was validated with the advantage of then being used to improve the aerodynamic performance of the JS1C Revelation 21 m tip’s flaperon. This improvement could be made by making use of a tailored bend-twist couple to reduce the effect of the aerodynamic load’s twist deflections. A test sample of the JS1C 21 m flaperon 3 was used to validate aeroelastic tailoring. The test sample was designed to be 1 m in length and have all the specified tailoring coupling characteristics that could improve the aerodynamic performance of the JS1C 21 m flaperon 3. The test sample was manufactured according to Jonker Sailplanes manufacturing standards and experimentally set up with the same applied deflections as in the analysis tool. The calculated bend-twist values and the experimental setup results were similar with a negligible difference, assuming small displacements and an aspect ratio greater than 13; this confirmed that the PreVABS/VABS/GEBT composite structure analysis tool could be used in aeroelastic tailoring to predict and design the bend-twist couple needed to improve the aerodynamic performance of the JS1C 21 m. While the twist behaviour of Flaperon 3 was improved by the tailored bend-twist couple, it was still necessary to add pre-twist as well, to fully address the effects of twisting by aerodynamic forces. / MIng (Mechanical Engineering), North-West University, Potchefstroom Campus, 2014

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No description available.

No description available.

In this thesis, a joint experimental and theoretical investigation of the vector properties that describe the inelastic scattering of a diatomic radical with an atomic collision partner is presented. A particular emphasis is placed on those correlations that include the final rotational angular momentum, j', of the radical. The depolarisation of both NO(A) and OH(A) brought about through collisions with krypton has been studied, providing a measure of the j-j' correlation, where j is the initial rotational angular momentum associated with the diatom. The total depolarisation cross- sections for both collisional disorientation and disalignment have been measured using quantum beat spectroscopy, and modelled theoretically using quasi-classical trajectory (QCT) calculations. The agreement between experiment and theory for NO(A)-Kr is excellent, but is not observed for OH(A)-Kr under thermal conditions. This has been attributed to the importance of electronic quenching in OH(A)-Kr. The depolarisation cross-sections have also been determined at a higher collision energy for OH(A)-Kr where electronic quenching is less significant, and the experimental results are in better agreement with those obtained theoretically. The NO(A)-Kr depolarisation cross-sections fall with increasing rotational quantum number, N, whereas for OH(A)-Kr, they exhibit less of an N dependence. This trend is mirrored in the elastic depolarisation cross-sections, which have also been determined experimentally for OH(A)-Kr. The significantly attractive and anisotropic nature of the OH(A)-Kr potential energy surface (PES) accounts for these observations. The j-j' correlation is extended to include the initial (relative) velocity (k) in a new theoretical treatment of the k-j-j' correlation. The formalism developed is used with the results from the QCT calculations for NO(A)-Kr and OH(A)-Kr to provide further insight into the mechanism of depolarisation in the two systems. Collisions of NO(A) with krypton do not cause significant depolarisation due to their impulsive nature, and the projection of j onto the kinematic apse is conserved. In contrast, collisions of OH(A) with krypton effectively randomise the direction of j, again showing the influence of the anisotropic and attractive nature of the PES. However, the projection of j onto the kinematic apse is still conserved. The inelastic scattering of NO(X) with argon and krypton has also been investigated, using a crossed molecular beam apparatus. The initial Λ-doublet state of the NO(X) was selected using hexapole focussing, and the products of the collision detected using velocity mapped ion imaging. The state to state differential cross-sections (equivalent to the k-k' correlation, where k' is the final relative velocity) have been measured for collisions which conserve the initial spin-orbit level of the NO(X) with krypton. The same parity dependent effects were seen as have been observed previously for NO(X)-Ar. The collision induced alignment (equivalent to the k-k'-j' correlation) of NO(X) as a result of scattering with argon has also been determined experimentally. The results can be explained classically by considering the conservation of the projection of j onto the kinematic apse.

L’architecture structurale et l’évolution du bassin d’avant-pays Pyrénéo-Alpin de Provence sont contrôlées par des failles profondes héritées du rifting de Gondwana au cours du Permo-Trias, par des variations d’épaisseur de la pile sédimentaire mésozoïque et par l'alternance d’évènements tectoniques compressifs et extensifs qui ont affecté la zone depuis la fin du Paléozoïque. La construction de deux coupes équilibrées d’échelle régionale (~150 km) montre que le style tectonique de l’avant-pays provençal est dominé par une tectonique de socle en Provence orientale et par une tectonique de couverture en Provence occidentale, associé avec du diapirisme dans les deux domaines. Les deux domaines sont couplés à l’échelle crustale et séparés par une zone d'accommodation dans la couverture: la Faille de la Moyenne Durance, dont la partie profonde est héritée du Paléozoïque. La structure actuelle de l’avant-pays Pyrénéo-Alpin de Provence correspond essentiellement à la signature de la compression Pyrénéo-Provençale Crétacé supérieur-Eocène (>90%). La part de la déformation Alpine est minime (9%). La phase d'extension Oligocène entre ces deux périodes compressives a été quantifiée à 1.7%. Les données de traces de fission sur apatite suggèrent une exhumation régionale à ~80 Ma reliée à la compression Pyrénéenne. Les chevauchements pyrénéens principaux ont joué simultanément, comme l’indiquent l’âge et la répartition des séries sédimentaires syntectoniques. / The structural architecture and evolution of the Pyrenean-Alpine foreland of Provence are controlled by deep-seated basement faults inherited from Gondwana rifting during Permo-Triassic time, by variations in the Mesozoic sedimentary pile thickness and by alternating compressive and extensive tectonic events that affected the area since the late Paleozoic. The construction of two balanced cross sections at regional scale (~150 km) shows that the structural style of the Provence foreland is dominated by thick-skinned tectonic in eastern Provence and thin-skinned tectonic in western Provence, associated with diapirism in each domain. Both domains are coupled at crustal scale and separated by an accommodation zone in the cover: the Middle Durance Fault, whose deep-seated part is inherited from the Paleozoic. The current structure of the Pyrenean-Alpine foreland of Provence mainly corresponds to the Pyrenean-Provence compression signature during Late Cretaceous to Eocene (>90%). The Alpine deformation proportion is minor (9%). The Oligocene extension phase between these two compressive periods has been quantified at 1.7%. The apatite fission track data suggests an exhumation stage around 80 Ma related to the Pyrenean compression. The main Pyrenean thrusts were synchronous, as indicated by the age and distribution of syntectonic sedimentary series.