Amendments pasted onto front end-cover. / Bibliography: p. 221-240. / xvi, 354 leaves : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Documents the experimental and analytical research undertaken aimed at providing the fundamental tools required to succesfully avoid the identified brittle "weak link" in the design of new and the assessment of existing unreinforced masonary buildings. / Thesis (Ph.D.)--University of Adelaide, Dept. of Civil and Environmental Engineering, 2000?

Storage of granular solids in silos has been the practice for many years. Engineers have been faced with the problem of making the silos empty more efficiently and minimising the forces acting on the walls of the silo during material discharge. To this end the anti-dynamic tube was invented. The tube has a smaller diameter than the silo and consists of several portholes along its height and around its circumference. When the discharge gate of the silo is opened the granular material enters the tube through the portholes, flows down the inside of the tube and exits the silo through the discharge gate. Most tubes have been installed such that there was sufficient space between the base of the tube and silo bottom for the granular material to flow simultaneously through the discharge gate. The flowing material causes a down drag on the tube from the friction of the granular material on the walls of the tube. Previous research has underestimated the magnitude of these frictional forces resulting in catastrophic buckling failure of the tubes, blocking the discharge gate of the silo. A blockage of the discharge gate requires top emptying of the silo resulting in financial losses and down time of equipment. A steel model silo with an anti-dynamic tube was set up in the laboratory to measure the friction on the tube during material flow. From the results of these experiments, an equation has been derived to estimate the magnitude of the down-drag force. Furthermore, an empirical expression was developed for the effects of the speed of the flowing material on the magnitude of the down-drag force. To keep construction costs down, it is necessary to optimise the wall thickness of the tube. There is currently no theory for the buckling capacity of a thin walled cylindrical shell with multiple perforations around its height and circumference. Therefore additional experiments were undertaken on a cylindrical shell with multiple perforations subjected to a combination of an axial as well as an external lateral pressure. Following on from the experiments, finite element analyses were undertaken to compare with the experimental results. For each finite element analysis an out-of-roundness was introduced as an initial wall imperfection. From these analyses and the cylinder experiments, a method of producing interaction curves for tubes with varying ratios of open area has been developed.

Thesis (M.Eng.Sc.)--University of Adelaide, School of Mechanical Engineering, 2005. / Includes bibliographical references (leaves 131-137). Also available electronically as part of the Australian Digital Theses Program.

Thesis (M.Eng.Sc.)--University of Adelaide, School of Mechanical Engineering, 2005. / Title from screen page; viewed 16 Aug. 2005. Includes bibliographical references (leaves 131-137). Also available in print format.

Thesis (Ph.D.)--University of Western Australia, 2003.

Thesis (M.E.-Res.)--University of Wollongong, 2008. / Typescript. Includes bibliographical references: leaf 163-172.

Thesis (M.S. in civil engineering)--Washington State University, December 2005. / Includes bibliographical references.

L'objectif scientifique de la thèse est de contribuer à améliorer la compréhension des mécanismes lésionnels découlant de l’impact non pénétrant d’un projectile en région thoracique latérale. Concrètement, l’application concerne l’amélioration de l’évaluation du potentiel lésionnel et l’optimisation de projectiles dits « à létalité réduite ». Cette étude a été menée dans le cadre du projet PARCHOC, associant la Délégation Générale pour l’Armement-Techniques Terrestres, le laboratoire PRISME de l’université d’Orléans, les sociétés Nexter munitions, ITC élastomère et ATCOM télémétrie. Il s’agit notamment de mettre en évidence les paramètres des projectiles qui doivent être maîtrisés pour limiter le risque lésionnel. Nous avons d’abord réalisé une étude pour caractériser des projectiles d'essais constitués d'un culot rigide et d'une ogive en mousse d'élastomère. Les propriétés dynamiques des élastomères ont été caractérisées par le système des barres de Hopkinson. Ce travail a permis la mise au point d'un modèle numérique de comportement des élastomères. Des essais ainsi que des simulations d’impacts sur cibles rigides ont ensuite été réalisés afin d'étudier l'influence du couple masse-vitesse et des caractéristiques mécaniques des élastomères sur le chargement généré. Dans la seconde partie de l'étude, des essais sur cibles biologiques instrumentées ont été menés à l’aide des projectiles d'études précédemment caractérisés. Les résultats expérimentaux et numériques montrent que la dangerosité des projectiles est liée à l’action qu’ils exercent sur la structure osseuse thoracique après sa fragilisation et que le mécanisme lésionnel est fortement dépendant de l’impulsion transmise par le projectile lors de l’impact. / The scientific objective of the thesis was to make a contribution in the understanding of the injury mechanisms following the blunt impact of a projectile on the lateral thoracic region. Practically, the application concerns safety certification and optimization of less-lethal projectile. This research was supported by the project PARCHOC partners: the Délégation Générale pour l’Armement-techniques terrestres, the PRISME laboratory (Orléans university),the companies Nexter munitions, ITC élastomère and ATCOM télémétrie. In particular, we have sought the principal projectile parameters which must be controlled to limit injury risk. Firstly, we have performed a study based on specialized test projectiles, made with a rear rigid part and soft foam (elastomeric) nose. The foams’ chemical formulations were made so that the dynamical properties (measured with the Hopkinson bar apparatus) were those expected. Experiments and simulations of the impacts on rigid wall target have been made to investigate how the mass-velocity couple and the foam material properties influence the impact force. Secondly, an experimental campaign was made using pig anatomical parts and the projectiles previously studied. Experimental and numerical results obtained during the thesis demonstrate that the dangerous nature of the projectiles used is essentially linked to the action on the thoracic bone structure after it has been weakened by the impact. Furthermore, injuries are strongly dependent upon the impulse transmitted during the impact.

abstract: Recent studies of the occurrence of post-flutter limit cycle oscillations (LCO) of the F-16 have provided good support to the long-standing hypothesis that this phenomenon involves a nonlinear structural damping. A potential mechanism for the appearance of nonlinearity in the damping are the nonlinear geometric effects that arise when the deformations become large enough to exceed the linear regime. In this light, the focus of this investigation is first on extending nonlinear reduced order modeling (ROM) methods to include viscoelasticity which is introduced here through a linear Kelvin-Voigt model in the undeformed configuration. Proceeding with a Galerkin approach, the ROM governing equations of motion are obtained and are found to be of a generalized van der Pol-Duffing form with parameters depending on the structure and the chosen basis functions. An identification approach of the nonlinear damping parameters is next proposed which is applicable to structures modeled within commercial finite element software. The effects of this nonlinear damping mechanism on the post-flutter response is next analyzed on the Goland wing through time-marching of the aeroelastic equations comprising a rational fraction approximation of the linear aerodynamic forces. It is indeed found that the nonlinearity in the damping can stabilize the unstable aerodynamics and lead to finite amplitude limit cycle oscillations even when the stiffness related nonlinear geometric effects are neglected. The incorporation of these latter effects in the model is found to further decrease the amplitude of LCO even though the dominant bending motions do not seem to stiffen as the level of displacements is increased in static analyses. / Dissertation/Thesis / Masters Thesis Mechanical Engineering 2015

abstract: The present investigation is part of a long-term effort focused on the development of a methodology for the computationally efficient prediction of the dynamic response of structures with multiple joints. The first part of this thesis reports on the dynamic response of nominally identical beams with a single lap joint (“Brake-Reuss” beam). The observed impact responses at different levels clearly demonstrate the occurrence of both micro- and macro-slip, which are reflected by increased damping and a lowering of natural frequencies. Significant beam-to-beam variability of impact responses is also observed. Based on these experimental results, a deterministic 4-parameter Iwan model of the joint was developed. These parameters were randomized following a previous investigation. The randomness in the impact response predicted from this uncertain model was assessed in a Monte Carlo format through a series of time integrations of the response and found to be consistent with the experimental results. The availability of an uncertain computational model for the Brake-Reuss beam provides a starting point to analyze and model the response of multi-joint structures in the presence of uncertainty/variability. To this end, a 4-beam frame was designed that is composed of three identical Brake-Reuss beams and a fourth, stretched one. The response of that structure to impact was computed and several cases were identified. The presence of uncertainty implies that an exact prediction of the response of a particular frame cannot be achieved. Rather, the response can only be predicted to lie within a band reflecting the level of uncertainty. In this perspective, the computational model adopted for the frame is only required to provide a good estimate of this uncertainty band. Equivalently, a relaxation of the model complexity, i.e., the introduction of epistemic uncertainty, can be performed as long as it does not affect significantly the uncertainty band of the predictions. Such an approach, which holds significant promise for the efficient computational of the response of structures with many uncertain joints, is assessed here by replacing some joints by linear spring elements. It is found that this simplification of the model is often acceptable at lower excitation/response levels. / Dissertation/Thesis / Masters Thesis Mechanical Engineering 2016