4,057 research outputs found
[Report from H. H. Stringer to Chief J. E. Curry, concerning the arrest of Lee Harvey Oswald #2]
No full textReport written by H. H. Stringer to Chief J. E. Curry concerning the arrest of Lee Harvey Oswald. Stringer describes searching a pickup truck in the alley behind the Texas Theater
[Report from H. H. Stringer to Chief J. E. Curry, concerning the arrest of Lee Harvey Oswald #1]
No full textReport written by H. H. Stringer to Chief J. E. Curry concerning the arrest of Lee Harvey Oswald. Stringer describes searching a pickup truck in the alley behind the Texas Theater
[Report by Sergeant of Police H. H. Stringer to Chief of Police J. E. Curry, December 3, 1963 #3]
No full textReport from Sergeant of Police H. H. Stringer to Chief of Police J. E. Curry, describing his participation in the arrest of Lee Harvey Oswald
Modelling Skin-Stringer Separation in a Post-Buckled Composite Stiffened Panel through Single Stringer Specimens
No full textThe collapse of composite stiffened panels in compression is complex and involves the interactions of many different failure modes. However, when the panel is allowed to enter the post-buckling regime, skin-stringer separation due to the interaction of the post-buckling deformations with the skin-stringer interface is often the critical failure mode. The accurate prediction of skin-stringer separation in these types of panels is therefore crucial for their design. Due to the high computational costs associated with modelling damage in a large multistringer panel and the manufacturing and testing costs associated with testing such a panel, single stringer specimens that accurately represent the behaviour of critical regions in these panels have been proposed in literature. In this thesis, transversely loaded single stringer specimens are designed and verified and are used to predict skin-stringer separation in the critical regions of a specific multistringer panel. A specific composite stiffened panel is considered that contains a skin of a tape material and four co-cured stringers of a fabric material. At the intersections of the skin and stringers, resin-rich noodle regions are created. A buckling analysis is first performed on the panel to obtain its post-buckling deformations. Based on these, two types of regions where skin-stringer separation may occur are identified; a mode I dominated skin-stringer separation at the minima of the buckling waves and a combined mode II and mode III skin-stringer separation at the inflection points of the buckling waves. A seven point bending specimen is designed based on the panel deformations near the former critical region, while a four point twisting specimen is designed based on the deformations near the latter region. Finally, detailed damage models are set up for the single stringer specimens to predict skin-stringer separation and the models are verified with the multistringer panel. The analyses showed that a mode I dominated skin-stringer separation is critical for this panel. The detailed analysis of the four point twisting specimen showed that no damage occurred at the inflection point. To predict the skin-stringer separation at the minimum, a verified seven point bending specimen has successfully been obtained. To do so, it was important to accurately simulate the deformation of the skin at the stringer flange edge, since this proved to be driving for the initiation and propagation of skin-stringer separation. Next to that, a trilinear cohesive law was used to capture the R-curve effect in the tape/fabric interfaces. Finally, a first assessment of the noodle region behaviour showed that damage in this region will probably happen at the location of maximum bending. Recommendations for future research have been provided.Aerospace Engineerin
Stringer, P E, SX9012
No full textThis record was harvested from a previous catalogue system and will be withdrawn in 2025. Information in this record may be superseded or incomplete. Visit this record in UMA's new catalogue at: https://archives.library.unimelb.edu.au/nodes/view/419758Surname: STRINGER. Given Name(s) or Initials: P E. Military Service Number or Last Known Location: SX9012. Missing, Wounded and Prisoner of War Enquiry Card Index Number: 24689.244337
Item: [2016.0049.52019] "Stringer, P E, SX9012
In search of the neanderthals: solving the puzzle of human origins
No full textEver since the first discovery of their bones, the Neanderthals have provoked controversy. Who were they? How were they related to modern people? What caused their disappearance 35,000 years ago? The Neanderthals have become the archetype of all that is primitive. But what is their true story? Today Neanderthal specialists are locked in one of the fiercest debates in modern science. One side, the "multiregional" school, argues that the Neanderthals and their contemporaries evolved semi-independently into modern humans. Christopher Stringer leads the "out of Africa" school, which believes that the Neanderthals were replaced by modern people from Africa. Here he sets out his views for the first time, with the archaeologist Clive Gamble. Step by step the authors put forward their case. The Neanderthals had an anatomy crucially different from our own, adapted to Ice Age Europe. Neanderthal behaviour similarly points to fundamental differences. New genetic evidence strongly suggests a single origin for modern humans in Africa. The authors argue that, capable and intelligent as the Neanderthals were, they proved no match for the better-organized, better-equipped newcomers, and died out
Effect of Composite Stiffened Panel Design on Skin-Stringer Separation in Postbuckling
No full textTo design aeronautical composite multi-stringer panels that can safely operate in a postbuckled state, it is important to identify the parameters that can influence the different modes in which skin-stringer separation might occur. A methodology is under development to study the interaction between the skin-stringer separation and the postbuckling deformation using the building block approach and single-stringer specimens. In particular, the methodology can identify whether the skin-stringer separation occurs due to bending or twisting, so that these two possible modes can be studied separately. For bending, a simple criterion that can predict the location of initiation is presented. This procedure has the potential to reduce the overall development cost and allows the investigation of the design parameters that influence the skin-stringer separation.Virtual/online event due to COVID-19Aerospace Structures & Computational Mechanic
Study of Skin-Stringer Separation in Postbuckled Composite Aeronautical Panels
No full textAeronautical composite stiffened structures have the capability to carry loads deep into postbuckling, yet they are typically designed to operate below the buckling load to avoid potential issues with durability and structural integrity. Large out-of-plane postbuckling deformation of the skin can result in the opening of the skin-stringer interfaces, especially in the presence of defects, such as impact damage. To ensure that skin-stringer separation does not propagate in an unstable mode that can cause a complete collapse of the structure, a deeper understanding of the interaction between the postbuckling deformation and the development of damage is required. The present study represents a first step towards a methodology to assess and improve the capabilities of stiffened composite structures subjected to postbuckling deformations.Two regions are identified in a four-stringer panel in which skin-stringer separation can occur, namely the region of maximum deformation and the region of maximum twisting. Both regions are studied using a finite element model of a representative single-stringer specimen. For the region of maximum deformation, a seven-point bending configuration is used, in which five supports and two loading points induce buckling waves to the specimen. The region of maximum twisting is approximated using an edge crack torsion configuration, with two supports and two loading points. These two configurations are studied by changing the positions of the supports and the loading points. An optimization procedure is carried out to minimize the error between the out-of-plane deformation of the representative single-stringer specimen and the corresponding region of the four-stringer panel. The optimal configurations are applied to a finite element model of a single-stringer specimen including cohesive elements to simulate damage initiation. The types of damage initiation that occur in these configurations are compared to the global/local analysis of the two identified regions of the four-stringer panel. Furthermore, the effect of the position of the supports and loading points on damage initiation is investigated. The edge crack torsion configuration that is found to be the best at approximating the twisting deformation of the panel also shows the most similarity in damage characteristics with respect to the four-stringer panel.Aerospace Engineerin
Study of Skin-Stringer Separation in Postbuckled Composite Aeronautical Structures
No full textAeronautical composite stiffened structures have the capability to carry loads deep into postbuckling, yet they are typically designed to operate below the buckling load to avoid potential issues with durability and structural integrity. Large out-of-plane postbuckling deformation of the skin can result in the opening of the skin-stringer interfaces, especially in the presence of defects, such as impact damage. To ensure that skin-stringer separation does not propagate in an unstable mode that can cause a complete collapse of the structure, a deeper understanding of the interaction between the postbuckling deformation and the development of damage is required. The present study represents a first step towards a methodology based on analysis and experiments to assess and improve the strength, life, and damage tolerance of stiffened composite structures subjected to postbuckling deformations. Two regions were identified in a four-stringer panel in which skin-stringer separation can occur, namely the region of maximum deflection and the region of maximum twisting. Both regions have been studied using a finite element model of a representative single-stringer specimen. For the region of maximum deflection, a seven-point bending configuration was used, in which five supports and two loading points induce buckling waves to the specimen. The region of maximum twisting was studied using an edge crack torsion configuration, with two supports and two loading points. These two configurations were studied by changing the positions of the supports and the loading points. An optimization procedure was carried out to minimize the error between the out-of-plane deformation of the representative single-stringer specimen and the corresponding region of the fourstringer panel.Aerospace Structures & Computational Mechanic
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