Dissertations / Theses: 'Stresses - structural'

1

Harrington, Joshua S. "Measurement of structural stresses using hole drilling." Thesis, University of British Columbia, 2015. http://hdl.handle.net/2429/55049.

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From a measurement standpoint structural stresses can be divided into two broad categories: stresses that can be measured straightforwardly by adjusting loads, e.g., live loads on a bridge, and those that are much more difficult, e.g., gravitational loads and loads due to static indeterminacy. This research focuses on the development of a method that combines the hole-drilling technique, a method used to measure residual stresses, and digital image correlation (DIC), an optical method for determining displacements, to measure these difficult-to-measure structural stresses. The hole-drilling technique works by relating local displacements caused by the removal of a small amount of stressed material to the material stresses. Adapting the hole-drilling technique to measure structural stresses requires scaling the hole size and modifying the calculation approach to measure deeper into a material. DIC is a robust means to measure full-field displacements and unlike other methods used to measure hole-drilling displacements, can easily be scaled to different hole sizes and corrected for measurement artifacts. There are three primary areas of investigation: the modification of the calculation method to account for the finite thickness of structural members, understanding the capabilities and limitations of DIC for measuring hole-drilling displacements, and evaluating the effects hole cutting has on the measurement. Experimental measurements are made to validate the measurement method as well as apply it to the real world problem of measuring thermally induced stresses in railroad tracks.
Applied Science, Faculty of
Mechanical Engineering, Department of
Graduate

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2

Mehrkar-Asl, S. "Direct measurement of stresses in concrete structures." Thesis, University of Surrey, 1988. http://epubs.surrey.ac.uk/804391/.

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3

Meduoye, G. O. "Investigation into the stresses and strains in toothed belt under static loading." Thesis, Cardiff University, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.354746.

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4

Govender, Nishalin. "A parametric investigation into the membrane stresses of hydrostatically loaded circular and elliptic toroidal shells." Master's thesis, University of Cape Town, 2017. http://hdl.handle.net/11427/25284.

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This study explores the membrane stresses of hydrostatically loaded elliptical and circular toroidal tanks. Equations are derived, using the membrane theory of shells, to obtain equations which can accurately describe the meridional and hoop stress behaviour at locations sufficiently far away from any bending disturbance occurring within the shell. The derived expressions are validated using the finite element software ADINA, indicating excellent agreement between the analytical and numerical solutions. A parametric study is undertaken, whereby the membrane profiles for prolate, oblate and circular toroidal shells is investigated. Parameters which are varied are the opening and aspect ratio of toroidal shells. Stress resultant profiles are shown for numerous cases in order to aid designers on suitable ratios to minimise membrane stresses for use when designing hydrostatically loaded toroidal shells. Lastly, numerical examples are investigated, keeping the volume constant and comparing the surface area due to a variation of opening and aspect ratios. It was found that when investigating toroidal shells, considerations are required when choosing the aspect ratio and opening ratios. Based on the results obtained, compromises between prolate and circular cross-sections with relatively small opening ratios are recommended in order to minimise the cost and maximise the structural efficiency, based on the membrane stresses occurring within the shell.

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Zheng, Tieyu. "A study of residual stresses in thin anisotropic (silicon) plates." Diss., Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/17516.

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6

Dong, Hai. "Nano-scale structural characterization of polymers subjected to stresses and thermal variations." Diss., Georgia Institute of Technology, 2003. http://hdl.handle.net/1853/8515.

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7

Bavirisetty, Rambabu 1963. "COMPARISON OF STRESS RECOVERY ALGORITHMS." Thesis, The University of Arizona, 1987. http://hdl.handle.net/10150/276405.

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8

Chaudry, Zaffir Ahmed. "Enhanced induced strain actuator performance through discrete attachment to structural elements." Diss., This resource online, 1992. http://scholar.lib.vt.edu/theses/available/etd-06062008-171749/.

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9

Warren, Alexander V. R. "Empirical shear assessment of reinforced concrete bridge members." Thesis, Available from the University of Aberdeen Library and Historic Collections Digital Resources, 2008. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?application=DIGITOOL-3&owner=resourcediscovery&custom_att_2=simple_viewer&pid=25876.

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10

Ahern, Alexandra Anne. "Lineations and Structural Mapping of Io's Paterae and Mountains: Implications for Internal Stresses." BYU ScholarsArchive, 2016. https://scholarsarchive.byu.edu/etd/6201.

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Io, the most volcanically active body in the solar system, also has some of the tallest and steepest mountains. The mountains seem to be tectonic in origin, yet the methods of their formation have not been decisively constrained and their associations with volcanic paterae are yet unclear. We have compiled global spatial statistics on mountain dimensions and orientations, lineations attributed to structures, straight patera margins, and patera dimensions in order to better define their genetic relationships and the mechanisms forming each type of feature. Additionally, we have produced 4 regional structural maps of mountain complexes and have proposed tectonic histories. Global statistics show that paterae and mountains and their associated lineations are more common at low latitudes and that lineations attributed to tectonics have preferred azimuths of 45° and 135°, whereas straight patera margins and azimuths appear more random. Additionally, tectonic lineations tend to cluster to those of similar types and are smaller when closer together. Mountains in general on Io are isolated, varied in size and shape, and have no significant geographic patterns in those variations. These results may indicate that global-scale processes are involved in forming Io's tectonic structures, but that the diversity of mountain characteristics and the collapse of paterae adjacent to mountain complexes may be more regionally controlled. Mapping of the Hi'iaka, Shamshu, Tohil, and Zal regions has shown that Io's mountains reside in large, faulted-bounded crustal blocks, which have undergone modification through local responses of subsurface structures. Strike-slip motion along reactivated faults has led to the formation of both transpressional and transtensional features, creating tall peaks and low basins, some of which are now occupied by paterae. Subsurface structures play a large role in Io's mountain diversity. Based on interpretation of statistical results and on our localized mapping, we propose that Io's mountains result from a combination of crustal stresses involving both global and local-scale processes. Multiple faults and fractures in a variety of orientations formed in Io's lithosphere, created over billions of years by stresses imposed by volcanic loading and tidal flexing. These faults have been progressively buried over time under multiple layers of volcanic material. Stresses continuing from loading and tidal massaging sometimes occur at oblique angles to pre-existing faults, reactivating them as reverse, normal, or strike-slip faults. Because of this, large, cohesive fault-bounded blocks have undergone both transpressional and transtensional modification. Further degradation of mountains has also occurred from extensive mass wasting, gravitational collapse, and erosion by sublimation and sapping of sulfur-rich layers within the crust. This model of fault-bounded blocks being modified by continual stresses and local structural response accounts for the variation and patterns of mountain sizes, shapes, and orientations, along with their isolation and interactions with other features. It presents an explanation for the influence of global and regional tectonics and a more detailed account of the formation of some of Io's remarkable mountains.

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11

Lalande, Frederic. "Modeling of the induced strain actuation of shell structures." Diss., This resource online, 1995. http://scholar.lib.vt.edu/theses/available/etd-02132009-171909/.

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12

Jin, Si. "Structural damage detection using higher-order finite elements and a scanning laser vibrometer /." free to MU campus, to others for purchase, 2000. http://wwwlib.umi.com/cr/mo/fullcit?p9974641.

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13

Peter, Geoffrey J. M. "Numerical simulation of CTE mismatch and thermal-structural stresses in the design of interconnects /." Full text open access at:, 2001. http://content.ohsu.edu/u?/etd,235.

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14

Zhou, Ding, and 周叮. "Three-dimensional vibration analysis of structural elements using Chebyshev-Ritz method." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2003. http://hub.hku.hk/bib/B27511200.

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15

Zibdeh, Hazim S. "Environmental thermal stresses as a first passage problem." Diss., Virginia Polytechnic Institute and State University, 1985. http://hdl.handle.net/10919/49971.

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Due to changes of the thermal environment, thermal stresses are produced in structures. Two approaches based on the stochastic process theory are used to describe this phenomenon. The structure is idealized as a long hollow viscoelastic cylinder. Two sites are considered: Barrow (AK) and Yuma (AZ). First passage concepts are applied to characterize the reliability of the system. Crossings are assumed to follow either the behavior of the Poisson process or Markov process. In both cases, the distribution of the time to first passage is taken to be the exponential distribution. Because the material is viscoelastic, statistically and time varying barriers (strengths) with Normal, Log-Normal, or Neibull distributions are considered. Degradation of the barriers by aging and cumulative damage are incorporated in the analysis.
Ph. D.
incomplete_metadata

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16

Alemdar, Bulent Nedim. "Distributed plasticity analysis of steel building structural systems." Diss., Georgia Institute of Technology, 2001. http://hdl.handle.net/1853/22220.

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17

Gardner, Brian Michael. "Visualization and stress analysis of complex three-dimensional structures." Thesis, Georgia Institute of Technology, 1996. http://hdl.handle.net/1853/17382.

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18

Sarma, Abhijit. "High strain properties of advanced high strength spot welded steels." Diss., Columbia, Mo. : University of Missouri-Columbia, 2007. http://hdl.handle.net/10355/5997.

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Thesis (M.S.)--University of Missouri-Columbia, 2007.
The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on April 14, 2008) Includes bibliographical references.

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19

Lammi, Christopher James. "The Effects of Processing Residual Stresses on the Fatigue Crack Growth Behavior of Structural Materials." Digital WPI, 2009. https://digitalcommons.wpi.edu/etd-theses/1108.

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"Residual stresses are a common and often undesired result of material processing, introduced through non-linear deformation and/or phase transformation of material under mechanical or thermo-mechanical loading. These macro stresses alter mechanical properties and the intrinsic fatigue crack growth characteristics of the material. Residual stress artifacts can introduce inconsistencies and significant errors when the true material behavior is needed for material development and optimization and for structural component design. The effects of quenching residual stresses on fatigue crack propagation behavior of various materials were investigated. In parallel, residual stresses similar in magnitude and distribution with the quenching residual stresses were generated using mechanical processes to decouple the effects of residual stresses from microstructural effects. Mechanical residual stress distributions predicted by 3D elastic-plastic finite element analysis showed good agreement with the stresses measured on fatigue crack growth testing specimens using fracture mechanics approaches. Crack propagation characteristics in fields with low and high residual stresses were studied using optical and scanning electron microscopy, and the effects of residual stress on crack path behavior were assessed. An original residual stress analytical correction to fatigue crack growth data was developed, compared to existing corrective methodologies, and validated using residual stress free data. Overall, the work provides tools to understand, control, and correct the effects of processing residual stresses on fatigue crack growth for accurate fatigue critical design and life predictions."

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20

Shoukr, Shoukry Latif. "Contact stresses in interference-fit joints with application to sugar-mill roller assemblies." Diss., The University of Arizona, 1989. http://hdl.handle.net/10150/184928.

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The interference-fit joint is widely used in machine design to connect two cylindrical machine elements. Its popularity comes from the simplicity of the assembly and the low cost of the production process. Even so, no study has examined the boundary non-linearities in the assembly of these joints. Moreover, the contact stresses and the stress concentration factors in interference-fit joints under torsional loads have not yet been examined in detail. In addition, the interface stresses and stress concentration factors in interference-fit joints subjected to bending loads have not been approached theoretically before. The sugar-mill roller is one of the oldest and most important examples of the interference-fit joints. The frequent fatigue failure of the sugar-mill rollers under reversed bending causes costly emergency line-shut downs. The versatility of the finite element method and the capability of the point-matching technique in handling contact problems have been combined, in the present work, to produce a surface-matching technique. It has been found that the complete-cohesion contact assumption may be acceptable for coefficients of friction ≥ 0.2, which is the case for most of the normally machined surfaces. An approach combining the semi-inverse displacement finite element method and the surface-matching technique has been developed to perform the torsional analysis. It has been found that the governing non-dimensional quantities are the ratio of the cohesion-length to the interface-length and the coefficient of friction divided by the load-level. The load-level is the ratio between the angle of twist of the shaft per unit length when the torque acts on the shaft alone and the amount of the diametral interference divided by the shaft diameter. A finite element model, using 8-noded solid elements together with linear interface elements, has been employed to locate the cohesion and slippage-zones in the sugar-mill roller under bending. The contact pressure increases along the compression side and decreases along the tension side. On the contrary, the interface shear decreases along the compression side due to bending and increases along the tension side. Subsequently, a larger slippage-length has been detected along the tension side.

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21

Sarwade, Rohit Foster Winfred A. "Life prediction analysis of a subscale rocket engine combustor using a fluid-thermal-structural model." Auburn, Ala., 2006. http://repo.lib.auburn.edu/2006%20Spring/master's/SARWADE_ROHIT_49.pdf.

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22

Lantz, Gabriel Antoine. "Crack detection using a passive wireless strain sensor." Thesis, Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/45773.

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Nearly one third of the 604,426 bridges in the United-States are either structurally deficient or functionally obsolete. Monitoring these bridges is essential to avoid catastrophic accidents. In steel bridges fatigue induced crack/rupture, which is one of the most common modes of failure, can be avoided if the crack is detected at the early stages of its formation. Cracks usually originate at stress concentration areas but their precise origin is random. Such strain concentration can be monitored with traditional strain gages, but their installation requires lengthy wires and equipment, which are expensive and labor intensive. Therefore wireless sensors are being developed to cope with these problems. In this work, a passive wireless strain sensor based on RFID technology is described. The sensor is a patch antenna that resonates at a certain frequency, which shifts in presence of strain. The relation between the resonance frequency and the strain is approximately linear. The slope of the relation is called sensitivity. The behavior of the sensor's sensitivity is studied using experimental work and simulations that couple electromagnetism and mechanics. The sensitivity measured in experiments and in simulations in presence of uniform strain is different. This difference is lower for the sensitivity in presence of a crack, probably due to a parameter variation that is currently not accurately modeled in the simulations.

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23

De, Bruin P. D. (Peter Douglas). "Experimental determination of the effective elastic constants of thin perforated plates." Thesis, Stellenbosch : Stellenbosch University, 1989. http://hdl.handle.net/10019.1/66862.

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24

Walker, John Griffith. "Investigation of induced strain actuator patches implementing modeling techniques and design considerations to reduce critical stress." Thesis, This resource online, 1993. http://scholar.lib.vt.edu/theses/available/etd-03042009-040453/.

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25

Bahen, Neil P. "Strut-and-tie modeling for disturbed regions in structural concrete members with emphasis on deep beams." abstract and full text PDF (free order & download UNR users only), 2007. http://0-gateway.proquest.com.innopac.library.unr.edu/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:1447626.

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26

Kriel, Thomas Edwin Slaughter. "Assessment of frequency domain force identification procedures." Diss., Pretoria : [s.n.], 2000. http://upetd.up.ac.za/thesis/available/etd-01122007-131828/.

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27

UREÑA, MARTÍN Carlos. "Study of Caveolae Mechanotransduction Under 3D Compressive Stresses : Comparative Analysis of 2 Models Mimicking Structural and Mechanical Tumor Characteristics." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLS525.

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La mécanique et le stress compressif jouent un rôle important dans la progression tumorale. Récemment, plusieurs approches ont été développées pour tester le stress en compression dans des modèles 3D in vitro. Dans le présent travail, nous montrons d’abord la pertinence de la compression dans l’organisation des fibroblastes associés au cancer (CAF), en enveloppant les cellules cancéreuses lors d’une compression isotrope 3D dans des capsules d’alginate creux. Dans ce système, les CAF couvrent les cellules cancéreuses en présence de compression selon un processus impliquant vraisemblablement une réorganisation du dépôt de fibronectine et non un réarrangement passif des deux sphéroïdes. Dans la deuxième partie de ce travail, nous avons étudié la réaction des composants de la cavéole au stress en compression.Les cavéoles sont des invaginations de la membrane plasmique capables d'amortir la tension de la membrane, protégeant ainsi la cellule de son éclatement. Nous montrons ici comment les cavéoles réduisent leur présence lors de la compression3D à court terme et comment cette compression inhibe l'activation de STAT1 et STAT3 induite par l'interféron. De plus, les effets à long terme des contraintes de compression sur les sphéroïdes entraînent également la perte du composant cavéole EHD2, une ATPase centrale pour la stabilité des cavéoles sur la membrane. Enfin, nous avons trouvé différentes voies avec une transcription modifiée du gène après un stress compressif. Parmi eux, nous avons caractérisé l'effet de la perte decavéoline-1 sur la libération d'exosomes sous compression 3D
Mechanics and compressive stress play an important role in tumor progression. Recently, several approaches have been developed to test compressive stress in 3D in vitro models. In the present work, we first show the relevance of compression in the organization of cancer associated fibroblasts (CAFs), enwrapping cancer cells upon 3D isotropic compression in capsules of hollow alginate. In this system, CAFs cover cancer cells in the presence of compression by a process which most likely involves fibronectin deposition reorganization, and not a passive rearrangement of the two spheroids. In the second part of this work, we investigated the response of caveolae components to compressive stress. Caveolae are plasma membrane invaginations which are able to buffer membrane tension, thus protecting the cell from bursting. Here, we show how caveolae reduce their presence under 3D short term compression, and how this compression inhibits interferon induced STAT1 and STAT3 activation. Moreover, long term effects of compressive stress in spheroids result also in loss of the caveolae component EHD2, acentral ATPase for caveolae stability on the membrane. Lastly, we found different pathways with altered gene transcription after compressive stress. Among them, we characterized the effect of caveolin-1 loss on the release of exosomes under 3Dcompression

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28

Buzio, Marco. "Structural effects of plasma instabilities on the JET tokamak." Thesis, Imperial College London, 1999. http://hdl.handle.net/10044/1/7574.

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29

Fink, Elliot G. "A stress-based fatigue life evaluation of two steel bridges along I-95 in Delaware." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file 3.03 Mb., ? p, 2006. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:1435862.

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30

Cross, Benjamin Thomas. "Analysis of the AASHTO fatigue design provisions for welded steel bridge details using reliability theory." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 101 p, 2007. http://proquest.umi.com/pqdweb?did=1338919111&sid=6&Fmt=2&clientId=8331&RQT=309&VName=PQD.

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31

Cai, Chao. "Analytical solutions for residual stresses in cold-formed steel circular hollow sections due to cold rolling." Thesis, University of Macau, 2009. http://umaclib3.umac.mo/record=b2148262.

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32

Salvati, Enrico. "Residual stress evaluation and modelling at the micron scale." Thesis, University of Oxford, 2017. https://ora.ox.ac.uk/objects/uuid:b737925e-a200-4a61-87f1-0d834d642d7b.

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The presence of residual stresses in engineering components may significantly affect damage evolution and progression towards failure. Correct evaluation of residual stress is of crucial importance for assessing mechanical components, predicting response and ensuring reliability. For example, when failure occurs due to cyclic loading, the underlying damage begins at the nano-, and then micro-scale. It is clear that improving engineering reliability at the micro-scale requires the ability to evaluate residual stress and mechanical properties at the appropriate scale. The key objective of the thesis is to advance the understanding and practice of residual stress evaluation at the micro-scale, and to examine the implications and applications that follow. Significant effort was devoted to the evaluation of two aspects of the relatively novel FIB-DIC micro-ring-core experimental technique: assessing the effects of Ga-ion damage and the quantification of uncertainty in stress evaluation due to unknown crystal orientation. FIB-DIC micro-ring-core milling was then used alongside with synchrotron XRD to study residual stress effects on fatigue crack growth propagation rate following the occurrence of overload or underload. The effects of the two principal mechanisms of crack retardation following an overload, residual stress and crack closure, were separated by testing samples at different loading ratios. Whilst, the acceleration after an underload was studied using validated non-linear FEM analyses. Conceptual focus was placed on the macro-micro-nano residual stress decomposition into Type I, II & III according to scale and, detailed examination was conducted experimentally and numerically. In the context of shot-peening surface treatment, residual stresses were modelled using a novel eigenstrain-based modelling procedure for arbitrarily shaped components. Furthermore, a fine scale characterisation was performed of the recast layer produced by EDM, with particular attention paid to the residual stress. The investigations presented in this thesis open new perspectives for the assessment of material reliability. Improved failure prediction models will be elaborated based on the insights obtained in the present study.

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33

Jara-Almonte, C. C. "Finite element analysis of subregions using a specified boundary stiffness/force method." Diss., Virginia Polytechnic Institute and State University, 1985. http://hdl.handle.net/10919/54448.

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The accurate finite element analysis of subregions of large structures is difficult to carry out because of uncertainties about how the rest of the structure influences the boundary conditions and loadings of the subregion model. This dissertation describes the theoretical development and computer implementation of a new approach to this problem of modeling subregions. This method, the specified boundary stiffness/force (SBSF) method, results in accurate displacement and stress solutions as the boundary loading and the interaction between the stiffness of the subregion and the rest of the structure are taken into account. This method is computationally efficient because each time that the subregion model is analyzed, only the equations involving the degrees of freedom within the subregion model are solved. Numerical examples are presented which compare this method to some of the existing methods for subregion analysis on the basis of both accuracy of results and computational efficiency. The SBSF method is shown to be more accurate than another approximate method, the specified boundary displacement (SBD) method and to require approximately the same number of computations for the solution. For one case, the average error in the results of the SBD method was +2.75% while for the SBSF method the average error was -0.3%. The comparisons between the SBSF method and the efficient and exact zooming methods demonstrate that the SBSF method is less accurate than these methods but is computationally more efficient. In one example, the error for the exact zooming method was -0.9% while for the SBSF method it was -3.7%. Computationally, the exact zooming method requires almost 185% more operations than the SBSF method. Similar results were obtained for the comparison of the efficient zooming method and the SBSF method. Another use of the SBSF method is in the analysis of design changes which are incorporated into the subregion model but not into the parent model. In one subregion model a circular hole was changed to an elliptical hole. The boundary forces and stiffnesses from the parent model with the circular hole were used in the analysis of the modified subregion model. The results of the analysis of the most refined mesh in this example had an error of only -0.52% when compared to the theoretical result for the modified geometry. The results of the research presented in this dissertation indicate that the SBSF method is better suited to the analysis of subregions than the other methods documented in the literature. The method is both accurate and computationally efficient as well as easy to use and implement. The SBSF method can also be extended to the accurate analysis of subregion models with design changes which are not incorporated into the parent model.
Ph. D.

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34

Filomeno, Coelho Rajan. "Multicriteria optimization with expert rules for mechanical design." Doctoral thesis, Universite Libre de Bruxelles, 2004. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/211184.

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Though lots of numerical methods have been proposed in the literature to optimize me-chanical structures at the final stage of the design process, few designers use these tools since the first stage. However, a minor modification at the first step can bring significant change to the global performances of the structure. Usually, during the initial stage, models are based on theoretical and empirical equations, which are often characterized by mixed variables: continuous (e.g. geometrical dimensions), discrete (e.g. the cross section of a beam available in a catalogue) and/or integer (e.g. the number of layers in a composite material). Furthermore, the functions involved may be non differentiable, or even discontinuous. Therefore, classical algorithms based on the computation of sensi-tivities are no more applicable.

Consequently, to solve these problems, the most wide-spread meta-heuristic methods are evolutionary algorithms (EAs), which work as follows: the best individuals among an initial population of randomly generated potential solutions are favoured and com-bined (by specific operators like crossover and mutation) in order to create potentially better individuals at the next generation. The creation of new generations is repeated till the convergence is reached. The ability of EAs to explore widely the design space is useful to solve single-objective unconstrained optimization problems, because it gener-ally prevents from getting trapped into a local optimum, but it is also well known that they do not perform very efficiently in the presence of constraints. Furthermore, in many industrial applications, multiple objectives are pursued together.

Therefore, to take into account the constrained and multicriteria aspects of optimization problems in EAs, a new method called PAMUC (Preferences Applied to MUltiobjectiv-ity and Constraints) has been proposed in this dissertation. First the user has to assign weights to the m objectives. Then, an additional objective function is built by linearly aggregating the normalized constraints. Finally, a multicriteria decision aid method, PROMETHEE II, is used in order to rank the individuals of the population following the m+1 objectives.

PAMUC has been validated on standard multiobjective test cases, as well as on the pa-rametrical optimization of the purge valve and the feed valve of the Vinci engine, both designed by Techspace Aero for launcher Ariane 5.

\
Doctorat en sciences appliquées
info:eu-repo/semantics/nonPublished

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35

Guzda, Mark Richard. "Development of site-specific fatigue truck weights and truck volume." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file 1.18 Mb., p, 2006. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:1435844.

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Mao, Baimin. "Predicting resilient modulus of highway subgrade soils in Ohio." Ohio : Ohio University, 1995. http://www.ohiolink.edu/etd/view.cgi?ohiou1179257407.

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Allen, Christine. "Role of end peeling in behavior of reinforced concrete beams with externally bonded reinforcement." Thesis, Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/33982.

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Aging bridges in the United States demand effective, efficient, and economical strengthening techniques to meet future traffic requirements. One such technique is to bond steel or fiber reinforced polymer (FRP) plates to the tension faces of reinforced concrete bridge beams with adhesives to strengthen them in flexure. However, beams that have been flexurally strengthened in this manner often fail prematurely, in particular by plate end peeling. The benefits of flexural strengthening by externally bonded reinforcement can only be fully realized by preventing premature failure modes so as to allow the development of composite action between the beam and the external reinforcement. With this goal in mind, several critical limit states of externally reinforced beams are examined in this thesis. Models developed by Roberts (1989) and by Colotti, Spadea, and Swamy (2004) that predict premature plate end debonding are examined in depth using data from previously conducted experimental programs that employed both steel and FRP external reinforcement. In addition, various parameters of the concrete beam, adhesive, and external reinforcement are analyzed in each model to determine the role of each parameter in failure prediction. A critical appraisal of the performance of the models using existing experimental data leads to the selection of the Roberts (1989) model. This model is used to develop recommended design guidelines for flexurally strengthening reinforced concrete bridge beams with externally bonded FRP plates and for preventing premature plate peeling.

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Nezamian, Abolghasem 1968. "Bond strength of concrete plugs embedded in tubular steel piles." Monash University, Dept. of Civil Engineering, 2003. http://arrow.monash.edu.au/hdl/1959.1/5601.

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Lokuge, W. P. (Weena Priyanganie) 1967. "Stress-strain behaviour of confined high strength concrete under monotonically increasing and cyclic loadings." Monash University, Dept. of Civil Engineering, 2003. http://arrow.monash.edu.au/hdl/1959.1/9425.

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Joaquim, Mauricio Martinelli. "Flexão e flexo-compressão em elementos de alvenaria estrutural." Universidade de São Paulo, 1999. http://www.teses.usp.br/teses/disponiveis/18/18134/tde-19042018-085707/.

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Este trabalho trata da verificação e dimensionamento de peças de alvenaria estrutural submetidas à flexão. Inicialmente são apresentados os conceitos básicos do método das tensões admissíveis e são desenvolvidos procedimentos para a análise do problema da flexão simples e composta reta. Em seguida discute-se o problema da flexão composta oblíqua, com ênfase à modelagem computacional necessária ao desenvolvimento de aplicativos para a análise de seções genéricas. São apresentados na seqüência dois programas computacionais, implementados a partir dos algoritmos e procedimentos desenvolvidos nos itens anteriores. Apresentam-se ainda tabelas e ábacos que permitem o cálculo das peças de alvenaria com rapidez, facilidade e segurança, algumas das quais nos moldes das já tradicionalmente utilizadas para o concreto armado. Por fim, diversos exemplos são apresentados, ilustrando a teoria exposta e a utilização de tabelas e ábacos apresentados.
This study deals with the design of structural masonry pieces subjected to bending loads. At first, basic concepts of the allowable stresses method are presented and procedures for the analysis of simple bending and composed bending are developed. Next, the oblique composed bending is discussed emphasising computational modelling for the analysis of generic cross sections. Two computational procedures based on the algorithms already developed are also shown. In addition, tables and abaci that allow analysing the design of masonry elements quickly, easily and safely are presented. Some of them are very similar to those used for reinforced concrete. Finally, several examples are presented.

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Heard, William Franklin. "Diagonal and horizontal stiffeners for shear transfer in rigid frame square knees." Master's thesis, Mississippi State : Mississippi State University, 2006. http://library.msstate.edu/etd/show.asp?etd=etd-11092006-214442.

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Bedynek, Agnieszka. "Structural behaviour of tapered steel plate girders subjected to shear." Doctoral thesis, Universitat Politècnica de Catalunya, 2014. http://hdl.handle.net/10803/145443.

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Tapered plate girders often form part of large-scale structures such as long continuous bridges or industrial buildings where due to considerable loads the higher resistance is required. There are several important reasons choosing non-prismatic girders. First of all, their tapered shape with gradually changing inertia allows for more effective stress distribution inside the web-panel and contributes to steel reduction and thereby to decrease the overall cost of the structure. Trapezoidal shape of such panels also may be desirable in structures with non-standard shape for example where pre-formed service openings are needed. Although rectangular plate girders were studied in many occasions in last few decades, the latest investigations have shown that the structural behaviour of tapered panels is more complex and different distribution of the internal forces takes place. Due to a lack of design rules for assessment of ultimate shear resistance of tapered plate structures with considerable angle of a slope (> 10 degrees), this research is focused on searching for a solution of the problem. The main body of the thesis is composed of four independent publications where each of them summarizes different phase of the research. The most relevant issues related to tapered panels discussed in the papers were: the critical shear load in tapered simple-supported plates, the influence of geometrical and structural imperfections, the optimal position of the longitudinal stiffener, the Resal effect, and finally the ultimate shear resistance of stiffened and unstiffened tapered plate girders. Nevertheless, the main objective of this work was the development of a reliable design tool to assess of the ultimate shear resistance of non-prismatic plate girders. The methodology applied in the research consists of the following stages: study of the bibliography and initial theoretical research, development of a numerical model, execution of two experimental programs, development of a wide parametric study, analysis of the experimental and numerical results, comparing them with those obtained according to EN 1993-1-5, and finally - development of a new design proposal for the assessment of the ultimate shear resistance for tapered steel plate girders. The PhD research was supported by two experimental programs focused on the structural behaviour of tapered plate girders. In the first program, transversally stiffened members subjected to shear and shear-bending interaction were tested. The second experimental program was focused on longitudinally stiffened tapered plate girders under shear. Results obtained from the experimental tests were used for the verification of the numerical model. Plate girders reveal tendency to possess a significant post-buckling resistance. This phenomenon can be observed as a diagonal tension field developing within the web-panel. In both experimental tests and numerical analyses, this characteristic behaviour was observed. Using verified the numerical model, a wide parametric study for a large number of tapered plate girders was carried out. All numerical results presented in this research were compared with those obtained according to EN 1993-1-5 and discussed. Finally, a new design method for the assessment of the ultimate shear resistance of tapered steel plate girders was presented. The new design proposal is based on the currently valid - Rotated Stress Field Method. The procedure maintains its simplicity and improves considerably results obtained for non-prismatic panels. This new reliable design tool, valid for any geometry and any typology of tapered steel plate girders, provides a solution of the main objective defined in this research

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Tran, Thi Thu Hang. "Combined application of structural geology, the mechanics of discrete media and the analysis of in situ stresses and displacements for the modelling of mechanical behaviour of fractured rock masses." Thesis, Montpellier 2, 2013. http://www.theses.fr/2013MON20018/document.

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Pour étudier le comportement mécanique des massifs rocheux, en prenant en compte le réseau des discontinuités au sein de la roche intacte, cette recherche a pour objectif la représentation du massif par des modèles géométriques basés sur des relevés de terrain et l'analyse de ces modèles par l'utilisation d'outils informatiques adaptés pour les milieux granulaires. Le premier chapitre fait l'état de l'art des roches fracturées, des méthodes numériques de la mécanique des roches et des approches du calcul de structure d'un tunnel. Ces études conduisent à la proposition d'une méthodologie depuis les recherches in situ jusqu'à la modélisation et l'analyse mécanique, présentée dans le deuxième chapitre. Le massif rocheux est d'abord représenté géométriquement par la distribution de ses discontinuités, et l'utilisation du logiciel RESOBLOK basé sur la méthode du Réseau de Fractures Discrètes. Les modèles mécaniques de massifs rocheux sont ensuite présentés à partir des données sur les études de l'histoire du massif, et des mesures faites sur site et en laboratoire. Les modèles numériques en 3D sont analysés par l'utilisation du logiciel LMGC90 basé sur la méthode de la Dynamique des Contacts Non Réguliers. Les premières applications de la méthodologie sont exposées : la création d'une roche numérique pour simuler un essai de compression triaxiale, et la simulation d'une excavation multi phases d'un tunnel au rocher. La méthodologie proposée a été appliquée sur le marbre blanc de Saint Béat (Haute Garonne, France) et les résultats préliminaires sont donnés dans le chapitre trois. Les réponses mécaniques de la roche numérique sont analysées et son comportement est caractérisé
Aimed at studying the mechanical behaviour of rock mass and considering the presence of the discontinuity network in the intact rock, this research concentrates on how the rock can be represented in suitable geometrical models, on the basis of site measurements, and then appropriately analysed using computer tools developed for the study of granular media. The first chapter deals with a bibliographical study on fractured rock and tunnel engineering. Different computational methods of rock mechanics are introduced. Simultaneously, three principal approaches for tunnel structural design are recalled. These studies lead to the proposition of a methodology from the in situ investigation to in-door modelling and mechanical analysis, presented in the second chapters. The rock mass is first geometrically represented through the distribution of discontinuities in the rock mass and the use of the RESOBLOK code based on the Discrete Fracture Network method. Mechanical models of rock mass are then presented from the data of historical studies on the rock mass and from laboratory and in situ measurements. The 3D computational models are analysed using the LMGC90 based on the Non Smooth Contact Dynamics method. The first two applications of the methodology are introduced: the generation of the numerical rock for the simulation of the triaxial compression test, and the simulation of multi-phase excavation of rock tunnel. The proposed methodology has been applied on the white marble of Saint Béat (Haute Garonne, France) and the initial results are given in the third chapter. The mechanical responses of the numerical rock mass are analysed and the bulk behaviour of the rock is evaluated

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Terdalkar, Sachin Sharad. "Graphically driven interactive stress reanalysis for machine elements in the early design stage." Link to electronic thesis, 2003. http://www.wpi.edu/Pubs/ETD/Available/etd-0818103-192248.

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Thesis (M.S.)--Worcester Polytechnic Institute.
Keywords: Stress Analysis; Machine Design; Combined Approximation Reanalysis; Structural Reanalysis; Design Process; FEM; Finite Element Analysis. Includes bibliographical references (p. 88-97).

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Santos, Elilde Medeiros dos. "Influência da alvenaria no comportamento estrutural de edifícios altos de concreto armado." Universidade Católica de Pernambuco, 2007. http://www.unicap.br/tede//tde_busca/arquivo.php?codArquivo=165.

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Apresenta-se neste trabalho a análise numérica de um edifício de 32 pavimentos, em concreto armado, situado na cidade do Recife. Primeiramente foi realizada a modelagem pelo método dos elementos finitos apenas para a estrutura em concreto. Em seguida realizou-se a modelagem considerando o efeito dos painéis de alvenaria de vedação no comportamento estrutural do edifício, através do modelo de barras diagonais equivalentes. E, depois, a modelagem mais refinada de alguns desses painéis, submetidos ao carregamento proveniente dos pórticos. Os resultados obtidos nos processamentos dos modelos com barras equivalentes e sem elas foram comparados entre si, a fim de se analisarem as reações de apoio e deslocamentos no topo do edifício para os dois modelos. Constatou-se um aumento na rigidez do edifício, bem como a redistribuição dos esforços. Foram analisados também os esforços nos painéis de alvenaria a fim de se verificar em que pavimentos e em que geometria de pórticos as alvenarias estavam sujeitas a maiores tensões
The work presents results from numerical analyses performed in a 32-storey reinforced concrete building in Recife. Numerical finite element analyses were performed taking into account the modeling of reinforced concrete members only as well as the masonry infill panels, considered as equivalent diagonal struts. It was also analyzed a more refined model consisting of isolated infill masonry panels subjected to frame loading from 3-D finite element analyses. Support reaction, stress resultants and displacements on the top of the buildings, obtained from performed analyses, were compared. An increase in building stiffness was observed as well as stress resultant redistribution. Infill masonry panel stresses were also investigated in order to find out the places where it is most stressed

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Agboka, Kossiga. "Développement d'un modèle thermomécanique axisymétrique en milieu semi-transparent avec transfert radiatif : application au fluage et à la trempe des verres." Thesis, Valenciennes, 2018. http://www.theses.fr/2018VALE0025/document.

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La majorité des produits verriers du marché sont issus d’une opération de mise en forme à hautes températures, suivie d’une phase de refroidissement contrôlé afin d’éliminer (verre recuit) ou générer (verre trempé) des contraintes résiduelles. Le comportement mécanique du verre étant fortement thermo-dépendant, le contrôle des températures est un élément déterminant pour le succès du procédé de fabrication. Lors de la simulation numérique, pour ce milieu semi-transparent, les échanges thermiques par conduction et par rayonnement sont à considérer. La résolution de l’ETR (Equation de Transfert Radiatif) est menée dans cette thèse par le biais de la « Méthode P1 » et le « Back Ray Tracing » (BRT). Les deux codes développés ont été validés par l’étude comparative avec les données en températures et en contraintes résiduelles issues de la littérature sur le refroidissement dans l’épaisseur du verre soumis à des conditions variées en convection naturelle et forcée. Une expérimentation qui consiste à refroidir un disque de verre sur un support métallique a été développée dans le but de comparer les températures et contraintes générées par l’expérimentation et par la modélisation issue du couplage thermomécanique avec les deux codes P1 et BRT. De manière plus originale, la méthode BRT a été étendue à des géométries de révolution. Une première approche a consisté à étudier le fluage d’une goutte de verre et à analyser l’influence du choix du modèle de résolution de l’ETR sur les températures et les géométries au cours de la mise en forme
Most of glass products on the market come from a high-temperature forming operation, followed by a controlled cooling phase to remove (annealed glass) or generate (tempered glass) residual stresses. Since the mechanical behaviour of the glass is highly thermo-dependent, temperature control is a determining factor for the success of the manufacturing process. During numerical simulations, for this semi-transparent medium, heat exchanges by conduction and radiation have to be considered. In this work, the resolution of the ETR (radiative transfer Equation) is carried out using the "P1 method" and the "Back Ray tracing" (BRT). The two developed codes were validated by the comparative study with the temperature and residual stresses data from the literature on cooling in the thickness of the glass subject to various conditions in natural and forced convection. An experimentation which consists in cooling a glass disk on a metal support was developed in order to compare the temperatures and stresses generated by the testing and by the modelling resulting from the thermomechanical coupling with the two codes P1 and BRT. In a more original way, the BRT method was extended to revolving geometries. A first approach was to study the creep of a glass gob and to analyze the influence of the choice of the ETR's resolution model on the temperatures and geometries during the forming

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Hwa, Ken. "Toward advanced analysis in steel frame design." Thesis, University of Hawaii at Manoa, 2003. http://proquest.umi.com/pqdweb?index=0&did=765960991&SrchMode=1&sid=1&Fmt=2&VInst=PROD&VType=PQD&RQT=309&VName=PQD&TS=1209158261&clientId=23440.

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Lao, Wai Keong. "Stress intensity factors for deep circumferential external surface cracks in hollow cylinders." Thesis, University of Macau, 2004. http://umaclib3.umac.mo/record=b1445132.

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Avachat, Siddharth. "Experimental and numerical analyses of dynamic deformation and failure in marine structures subjected to underwater impulsive loads." Thesis, Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/44904.

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The need to protect marine structures from the high-intensity impulsive loads created by underwater explosions has stimulated renewed interest in the mechanical response of sandwich structures. The objective of this combined numerical and experimental study is to analyze the dynamic response of composite sandwich structures and develop material-structure-property relations and design criteria for improving the blast-resistance of marine structures. Configurations analyzed include polymer foam core structures with planar geometries. A novel experimental facility to generate high-intensity underwater impulsive loads and carry out in-situ measurements of dynamic deformations in marine structures is developed. Experiments are supported by fully dynamic finite-element simulations which account for the effects of fluid-structure interaction, and the constitutive and damage response of E-glass/polyester composites and PVC foams. Results indicate that the core-density has a significant influence on dynamic deformations and failure modes. Polymeric foams experience considerable rate-effects and exhibit extensive shear cracking and collapse under high-magnitude multi-axial underwater impulsive loads. In structures with identical masses, low-density foam cores consistently outperform high-density foam cores, undergoing lesser deflections and transmitting smaller impulses. Calculations reveal a significant difference between the response of air-backed and water-backed structures. Water-backed structures undergo much greater damage and consequently need to absorb a much larger amount of energy than air-backed structures. The impulses transmitted through water-backed structures have significant implications for structural design. The thickness of the facesheets is varied under the conditions of constant material properties and core dimensions. The results reveal an optimal thickness of the facesheets which maximizes energy absorption in the core and minimizes the overall deflection of the structure.

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Yang, Yang. "Stress intensity factors of circumferential semi-elliptical internal surface cracks of tubular member subjected to axial tensile loading." Thesis, University of Macau, 2010. http://umaclib3.umac.mo/record=b2182941.

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Dissertations / Theses on the topic 'Stresses - structural'

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