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Havlíková, Marie. "Diagnostika systémů s lidským operátorem." Doctoral thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2009. http://www.nusl.cz/ntk/nusl-233473.
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The doctoral thesis is thematically focused to human operator systems significantly contributing to this system reliability and safety. The theoretical part of the thesis is concerned with human activities and communications in MMS system, valuation and estimation of human reliability probability in MSS. The important part of the thesis is also a description of human operator neuromuscular system as an executive powerful system on MMS system regulating activities and the summary of human driver models in compensative lateral car control. The practical part of the doctoral thesis is based on analyses created by experimental data of drives. Experimental drives were done on drivers set following different backgrounds and different sleep deprivation at whole day. All experimental data was realized from the cooperation and following the agreement of Faculty of Transportation Science research centre on Prague ČVUT. Another part of thesis includes driver simulation model proposals with nonlinear components for lateral car control. Simulation model drives are compared with real drives or drivers on drive-simulator and there are monitored identical and different dynamic movement characteristics. The main target of doctoral thesis is to detect and obtain significant dynamical drive experience characteristics based on experimental data analyses. As well to found drive characters variability owing to driver’s fatigue and determinated evaluated characteristics changes. Acquired results of thesis should help in assistant systems that in cooperation with other components alert to micro-sleep and run off drive possibility.
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Doheney, Shaun W. "Sleep logistics as a force multiplier : an analysis of reported fatigue factors from Southwest Asia warfighters /." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2004. http://library.nps.navy.mil/uhtbin/hyperion/04Sept%5FDoheney.pdf.
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Kweon, Young-Gak. "Influence de divers paramètres sur la fissuration par fatigue d'aciers de construction dans l'eau de mer sous protection cathodique." Châtenay-Malabry, Ecole centrale de Paris, 1986. http://www.theses.fr/1986ECAP0010.
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Etude du comportement en fissuration par fatigue dans l'eau de mer sous protection cathodique des aciers destinés à la construction de structures off-shore (acier E355, acier non allié 0,06%C, acier allié 1%AL1%CR0,06%C, acier allié 0,43%CU0,06%C). Influence des divers paramètres agissant sur la fatigue-corrosion sous polarisation cathodique: paramètres électrochimiques (marnage, potentiel de polarisation cathodique, circulation et ph de la solution), paramètres mécaniques (cyclage, surcharge), paramètres métallurgiques (composition chimique de l'acier, soudage)
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Güngör, Güven. "Biaxial Load Effects on Fatigue Properties." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2019. http://amslaurea.unibo.it/19079/.
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This study aims to aid many issues related to fatigue, namely biaxial loading, the definition of the finite geometry correction factor of the stress intensity factor and the understanding of the energy dissipation per fatigue crack growth. In our work, we are using the geometry correction factor definition that uses the ratio
of external work introduced to the material. Using different biaxiality ratios varies the external work done, thus makes it possible for us to observe how the geometry correction factor handles this variation. The trend of strain energy release rate per crack growth is also investigated through biaxiality. Moreover,
the common discussion of the effects of biaxiality on fatigue properties is aided with yet another study. For this purpose, cruciform shaped plate specimen from an aluminum alloy are manufactured and biaxially loaded. Crack growth is observed while load-to-displacement data is recorded to evaluate the external work done on the specimen. As a result, it is seen that biaxiality delays the fatigue failure. Crack growth rates decreases as the biaxiality increases for a given effective stress intensity factor. Making use of the work values for the calculation of the finite geometry correction factor handles the effects of
biaxiality well. Strain energy release rate increases as the crack propagates, but there is no trend between strain energy release rate and biaxiality of the loading. In the future works, observing also the crack tip plasticity and trying out a wider range of biaxiality ratios with different types of material would result in more generalizable conclusions. Moreover, more repetitions of the fatigue tests would give more accurate values for the amount work introduced to the material with changing biaxiality.
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Ciomber, Isabelle, and Roland Jakel. "Systematic Analysis and Comparison of Stress Minimizing Notch Shapes : Obtaining a stress concentration factor of Kt=1 without FEM-Code." Universitätsbibliothek Chemnitz, 2014. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-141533.
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Als Stand der Technik sind einfache, kreisförmige Verrundungen zur Reduktion von Kerbspannungen an Querschnittsübergängen bekannt, für die aus Tabellenwerken / Diagrammen in der Literatur die Formzahl einfach abgelesen werden kann. Die Effizienz der Spannungsreduktion solcher Lösungen ist jedoch sehr begrenzt. Ziel der Arbeit ist es daher, dem Konstrukteur bzw. Berechnungsingenieur ein Verfahren in die Hand zu geben, mit dem er für Standardquerschnittsübergänge und Standardlastfälle "Nicht-Kreiskerben" ohne teure und zeitaufwendige FEM-Analyse einfach durch Nutzung geeigneter Formzahldiagramme auslegen kann. Dabei sind sogar Formzahlen von nahezu eins möglich, d.h., in der "Kerbe" bleibt praktisch nur noch die Nennspannung übrig. Die Präsentation ist zweitgeteilt: Im ersten Teil werden die Arbeitsmethoden bzw. Softwarefunktionen und verwendeten Softwarewerkzeuge vorgestellt: Dies sind die Programme Creo Parametric als vollparametrisches CAD-Werkzeug und Creo Simulate als p-FEM-Programm der Parametric Technology Coprporation (PTC). Der zweite Teil der Präsentation beschreibt den Gültigkeitsbereich sowie die untersuchten Kerbgeometrien: Die einfache kreisförmige Verrundung als Stand der Technik, die Zwei-Radien-Kerbe, die Baud-Kurve, die Methode der Zugdreiecke nach Claus Mattheck, die elliptische Kerbe sowie die konische Rundung als generalisierte elliptische Kerbe. Es wird kurz eine Bibliothek vorgestellt, mit der solche Kerben einfach ausgelegt werden können, d.h. Ihre exakte Geometrie festgelegt sowie die zugehörige Formzahl αk bestimmt werden kannCircular (one-radius) fillets are known as state-of-the-art for reducing notch stresses at cross section transitions. The stress concentration factor Kt of such geometries can be read out from diagrams/tables given in the literature. However, the efficiency of stress reduction of circular notches is very limited. The goal of the work therefor is to present a method for the designer/analyst how to design non-circular notches/fillets just by using suitable Kt-diagrams without time-consuming and expensive FEM analyses. Kt-numbers of nearly one are possible, that means in the "notch" just the nominal stress appears and no stress concentration takes place. The presentation has two parts: Part one describes the working methods and software functions as well as software tools: Creo Parametric as fully-parametric CAD program and Creo Simulate as embedded p-FEM-tool from Parametric Technology Corporation (PTC) have been used. The second part describes the range of validity and the examined notch geometries: The one-radius fillet as state-of-the-art, the two-radii filet, the Baud-curve, the method of tensile triangles from Claus Mattheck, the standard elliptical fillet and the conical round as generalized elliptical fillet. A notch layout library is shortly presented that allows to design such fillets, that means exactly determine the notch geometry and the related stress concentration factor Kt
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Musinski, William D. "Novel methods for microstructure-sensitive probabilistic fatigue notch factor." Thesis, Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/34704.
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An extensive review of probabilistic techniques in fatigue analysis indicates that
there is a need for new microstructure-sensitive methods in describing the effects
of notches on the fatigue life reduction in cyclically loaded components. Of special
interest are notched components made from polycrystalline nickel-base superalloys,
which are used for high temperature applications in aircraft gas turbine engine disks.
Microstructure-sensitive computational crystal plasticity is combined with novel probabilistic
techniques to determine the probability of failure of notched components
based on the distribution of slip within the notch root region and small crack initiation
processes. The key microstructure features of two Ni-base superalloys, a fine and
coarse grain IN100, are reviewed and the method in which these alloys are computationally
modeled is presented. Next, the geometric model of the notched specimens
and method of finite element polycrystalline reconstruction is demonstrated. Shear-based
fatigue indicator parameters are used to characterize the shear-based, mode I
formation and propagation of fatigue cracks. Finally, two different probabilistic approaches
are described in this work including a grain-scale approach, which describes
the probability of forming a crack on the order of grain size, and a transition crack
length approach, which describes the probability of forming and propagating a crack
to the transition crack length. These approaches are used to construct cumulative
distribution functions for the probability of failure as a function of various notch root
sizes and strain load amplitudes.
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Weitzel, Thomas R. "Fatigue : investigation of a human factor for aviation curricula." Doctoral diss., University of Central Florida, 1997. http://digital.library.ucf.edu/cdm/ref/collection/RTD/id/20654.
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University of Central Florida College of Education ThesisThis descriptive study investigated the perceived problem of human fatigue as an operational consideration within the U.S. air carrier industry and the status of fatigue as content within U.S. aviation education/training curricula. An instrument was developed and expert-validated for self-completion by the following three groups (each with its sample size): (a) aviation higher education, represented by a mailing to 50 individuals; (b) air carrier training/management, represented by a mailing to 50 individuals; and (c) a professional training group of 58 general aviation flight instructors, with administration by the researcher during scheduled company meetings. The resultant SPSS data set consisted of 116 cases. Eight demographic variables were reported and analyzed with the analysis of variance; and the definition of fatigue, a multiple choice item, was tested for the chi-square goodness-of-fit distribution. The remaining 21 variables were subjected to a factor analysis, utilizing principal-azis fatoring for extraction; orthogonal rotation, which forced the derived factors to be uncorrelated; and varimax, a variance maximizing procedure. The resultant 8 factors removed the duplication from the 21 correlated variables and, when scored, became variables within the SPSS data set. The normalized factor scores were subjected to analysis of variance and post hoc comparison for any significance of difference between the three groups; minor group differences were found for three of the eight factors. The data supported the literature review with respect to human fatigue being perceived as an operational consideration on the flightdecks of U.S. air carriers. The data and the literature also indicated that fatigue is present as content within U.S. aviation curricula. However, the answers to beth research questions involved a matter of degree. Additionally, the data indicated that not all students within U.S. aviation have exposure to fatigue content within their curricula. Teaching the concepts and management of fatigue to some of these student may be as important as (more important than) fatigue as curricular content for flight crews. Future research in the development of a curriculum paradigm for human fatigue in U.S. aviation might utilize the eight factors derived as constructs by the factor analysis utilized in this study.
Ed.D.;
Educational Services;
Education;
133 p.
ix, 133 leaves, bound : ill. ; 28 cm.
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Robinson, Teresa Michelle. "Predictive Factors of Compassion Fatigue Among Firefighters." ScholarWorks, 2016. https://scholarworks.waldenu.edu/dissertations/2332.
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Few existing studies have examined compassion fatigue among emergency responders even though firefighters and emergency medical service (EMS) professionals have repetitive direct exposure to traumatic events. This study focused on identifying predictor variables for the development of compassion fatigue in firefighters. Karasek's demand-control model, a commonly used work stress model, was the study's theoretical framework as it focuses on specific construct interactions that predict employee well-being. Accordingly, this correlational study examined the predictive nature of EMS license level, years of service, and personality type on the development of compassion fatigue in career firefighters. Data collection occurred with surveys incorporating the Professional Quality of Life Scale and the Big Five Inventory. Mid-Michigan fire departments participated with 129 career firefighters returning completed surveys with results analyzed using logistic regression. Findings revealed a significant predictive relationship between personality traits and the development of compassion fatigue. These findings can inform preventative measures that protect the psychological well-being of these emergency responders by informing and educating the professionals and organizations as to who is at greatest risk and ultimately providing opportunity for risk mediation.
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Pannemaecker, Alix de. "Etude du phénomène d'arrêt de propagation des fissures au travers d'un couplage multi-échelles fretting, fretting fatigue et essai fatigue C(T)." Thesis, Ecully, Ecole centrale de Lyon, 2015. http://www.theses.fr/2015ECDL0010/document.
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De nombreuses structures aéronautiques telles que les contacts aube/disque, rivet/tôle, assemblages frettés ou boulonnés subissent des endommagements de fretting fatigue dus à des sollicitations vibratoires. Ces sollicitations, qui combinent des chargements de contact de fretting (micro déplacements alternés) et de fatigue, peuvent induire des phénomènes de fissuration. L’objectif de cette thèse est d’identifier les mécanismes de propagation et d’arrêt de fissuration pour différentes configurations, impliquant des chargements de fretting et de fatigue. Différents aspects seront étudiés : - Les essais de fretting simple, fretting fatigue et fatigue seront corrélés de manière à mesurer certaines propriétés mécaniques de matériaux. Dans cette démarche, une méthode inverse permettant l’identification du seuil d’arrêt de propagation des fissures longues et courtes en fatigue à partir d’essais de fretting simple et fretting fatigue est introduite. - L’effet du rapport de charge est pris en compte afin de quantifier la fermeture de fissure pour les essais de fretting et fretting fatigue. Un nouveau modèle de fermeture sera proposé. - L’effet d’échelle est étudié grâce au développement d’une nouvelle machine de fretting fatigue permettant le suivi in situ des propagations de fissures sur des éprouvettes millimétriques. Le comportement des fissures courtes en fretting pendant un essai de fretting fatigue a été observé pour la première fois. L’idée principale de ce travail est de considérer que lors d’un essai en fretting simple, une condition d’arrêt de propagation est systématiquement atteinte. Les facteurs d’intensités de contraintes seuils en fatigue peuvent ainsi être extraits par une méthode inverse à partir des essais de fretting. La méthodologie adoptée consiste à mesurer la longueur de fissure maximale obtenue lors d’un essai de fretting correspondant à une condition d’arrêt de propagation. En jouant sur les chargements de fretting, les domaine des fissures courtes et longues sont étudiés. Pour chaque condition d’arrêt, le facteur d’intensité de contraintes seuil correspondant est calculé. Enfin, en traçant l’évolution de ce dernier en fonction de la longueur de fissure, une description complète des seuils d’arrêt de fissuration en fatigue peut être obtenue. Cette méthodologie est appliquée sur plusieurs configurations de fretting simple et est étendue aux essais de fretting fatigue. Ainsi une large gamme de rapports de charge peut être étudiée. Des essais conventionnels de fatigue propagation sur éprouvettes C(T) ont été réalisés de manière à valider complètement la démarche d’identification inverse des conditions d’arrêt de fissuration. Le manuscrit est divisé en six chapitres adoptant une évolution linéaire. Le chapitre 1 traite d’une revue bibliographique concernant la propagation des fissures courtes et longues en fatigue dans les matériaux métalliques, introduisant les phénomènes de fermeture. L’analyse est étendue à la propagation des fissures en fretting et fretting fatigue. Le chapitre 2 présente l’ensemble des techniques et méthodes expérimentales utilisées au cours de ce travail. Une analyse numérique et la méthode inverse d’identification des conditions d’arrêt de propagation sont introduites dans le chapitre 3. Les chapitres suivants traitent les différents résultats obtenus. Le chapitre 4 présente les essais de fretting simples menés sur différents matériaux métalliques. Une corrélation entre les conditions d’arrêt de fretting simple avec celles de fissures longues en fatigue est obtenue pour rapports de charge négatifs. Cette analyse est étendue aux rapports de charge positifs au chapitre 5 en couplant les essais de fretting simple, fretting précontraints et essais de fatigue C(T). Enfin, les effets d’échelle et la cinétique de propagation des fissures de fretting fatigue sont étudiés au chapitre 6Aircraft structures such as blade/disk, rivet/sheet and fretted or bolted assembly contacts are subjected to fatigue fretting damage caused by vibratory loads. These loads combining fretting (alternating micro displacements) and fatigue contact loading can induce cracks. The objective of this thesis is to identify the propagation and crack arrest mechanisms for different configurations involving fretting and fatigue loads. Various aspects will be studied : - Simple fretting, fatigue fretting and fatigue tests will be correlated in a way to measure some material mechanical properties. A reverse approach allowing to identify the long and short fatigue crack propagation thresholds from simple fretting and fretting fatigue will be introduced. - A new closure model taking into account the effect of loading ratio on crack closure in fretting and fretting fatigue tests will be proposed. - The scaling effect will be studied thanks to the development of a new fretting fatigue machine allowing for in-situ monitoring of the propagation of small scale cracks. The behavior of fretting short cracks has been observed for the first time in a fretting fatigue test. The main idea behind the current work is the consideration that for a simple fretting test, the crack will always lead to a crack propagation arrest condition. Threshold stress intensity factors can thus be extracted from fretting tests using a reverse method. The methodology used consists in measuring the longest fretting crack corresponding to a crack propagation arrest condition. Short and long crack regimes are studied by varying fretting loads and geometries. The corresponding threshold stress intensity factor is calculated for each arrest condition. A complete description of fatigue crack arrest thresholds can be obtained from a plot depicting the evolution of the stress intensity factor range as a function of crack length. This methodology has been applied on multiple simple fretting configurations and was extended to fretting fatigue tests allowing to study a large range of loading ratios. Conventional fatigue crack propagation tests were carried out on C(T) specimens in order to validate the reverse method used for crack arrest conditions. The present thesis is divided into six main chapters. Chapter 1 provides a complete literature review on short and long crack propagation in metallic materials introducing crack closure. It provides a treatment for both fretting and fretting fatigue including a comparative analysis. Chapter 2 provides an overview of the different techniques and methodologies used as part of this research project. The reverse method used for the identification of crack propagation arrest conditions as well as a numerical analysis are presented in Chapter 3. The following Chapters provide a treatment of the various results obtained. Chapter 4 focuses on simple fretting tests carried out on different metallic materials. A correlation between simple fretting and long fatigue crack arrest conditions was obtained for negative loading ratios. This analysis is extended to positive loading ratios in Chapter 5 combining simple fretting, prestressed fretting and C(T) fatigue tests. Finally, scaling effects and fretting fatigue crack propagation kinetics are studied in Chapter 6
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Lozano, Minguez Estivaliz. "Fatigue and fracture mechanics of offshore wind turbine support structures." Thesis, Cranfield University, 2015. http://dspace.lib.cranfield.ac.uk/handle/1826/9756.
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Wind power, especially offshore, is considered to be one of the most promising sources of ‘clean’ energy towards meeting the EU targets for 2020 and 2050. However, its popularity has always fluctuated with the price of fossil fuels since nowadays wind electricity production cannot compete with nuclear or coal electricity production. Support structures are thought to be one of the main drivers for reducing costs in order to make the wind industry more economically efficient. Foundations and towers should be fit for purpose, extending their effective service life but avoiding costs of oversizing. An exhaustive review of the background and state of the art of the Fatigue-Life assessment approaches has been carried out, combining analysis of the gathered experimental data and the development of Finite Element models based on contemporary 3D solid models with diverse Regression Analyses, in order to identify their weakness and evaluate their accuracy. This research shows that the guides and practices currently employed in the design and during the operation of the offshore wind turbine support structures are obsolete and not useful for optimisation, which generally leads to conservationism and an unnecessary increase in costs. The basis for a comprehensive update of the Girth Weld and Tubular Joint S-N curves and the Stress Concentration Factors of Tubular Joints has been set out. Furthermore, a reliable methodology for deriving the Stress Intensity Factor at the deepest point of a semi-elliptical surface saddle crack in a tubular welded T-joint has been proposed.
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Fan, Zhengxuan. "Atomistic simulation of fatigue in face centred cubic metals." Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLX076/document.
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La fatigue induite par chargement cyclique est un mode d'endommagement majeur des métaux. Elle se caractérise par des effets environnementaux et de grandes dispersions de la durée de vie qui doivent être mieux comprises. Les matériaux analysés sont de type cfc : aluminium, cuivre, nickel et argent. Le comportement de marches naturellement créées en surface par le glissement cyclique de dislocations est examiné par simulations en dynamique moléculaire sous vide et sous environnement oxygène pour le cuivre et le nickel. Un phénomène de reconstruction est observé sur les marches en surface, qui peut induire une forte irréversibilité. Trois mécanismes de reconstruction des marches apparues en surface sont observés et décrits. L’irréversibilité de ces marches est ensuite analysé. Elles sont irréversibles pour des chargements expérimentaux, sauf arrivée de dislocations de signe opposé sur un plan de glissement directement voisin.Avec arrivée de dislocations sur des plans non voisins, l'irréversibilité s’accumule cycle par cycle et il est possible de reproduire l’apparition de fissures en surface dont la profondeur augmente graduellement.Un environnement oxygène modifie la surface (début d’oxydation) mais pas l’irréversibilité parce que l’oxygène n’a pas d'influence majeure sur les différents mécanismes liés à l’évolution du relief.Une estimation grossière de l'irréversibilité est faite pour des dislocations coin pures dans une bande de glissement persistante pour les matériaux dits ondulés. On obtient un facteur d’irréversibilité entre 0,5 et 0,75 pour le cuivre, sous vide et sous l’environnement oxygène, en accord avec des mesures récentes en microscopie à force atomique.La propagation de fissures est simulée en environnement inerte. Les fissures peuvent se propager à cause de l'irréversibilité des dislocations générées, liée à leurs interactions allant jusqu’à la création de jonctionsFatigue is one of the major damage mechanisms of metals. It is characterized by strong environmental effects and wide lifetime dispersions which must be better understood. Different face centred cubic metals, Al, Cu, Ni, and Ag are analyzed. The mechanical behaviour of surface steps naturally created by the glide of dislocations subjected to cyclic loading is examined using molecular dynamics simulations in vacuum and in air for Cu and Ni. An atomistic reconstruction phenomenon is observed at these surface steps which can induce strong irreversibility. Three different mechanisms of reconstruction are defined. Surface slip irreversibility under cyclic loading is analyzed. All surface steps are intrinsically irreversible under usual fatigue laboratory loading amplitude without the arrival of opposite sign dislocations on direct neighbor plane.With opposite sign dislocations on non direct neighbour planes, irreversibility cumulates cycle by cycle and a micro-notch is produced whose depth gradually increases.Oxygen environment affects the surface (first stage of oxidation) but does not lead to higher irreversibility as it has no major influence on the different mechanisms linked to surface relief evolution.A rough estimation of surface irreversibility is carried out for pure edge dislocations in persistent slip bands in so-called wavy materials. It gives an irreversibility fraction between 0.5 and 0.75 in copper in vacuum and in air, in agreement with recent atomic force microscopy measurements.Crack propagation mechanisms are simulated in inert environment. Cracks can propagate owing to the irreversibility of generated dislocations because of their mutual interactions up to the formation of dislocation junctions
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Taylor, Janice D., University of Western Sydney, College of Social and Health Sciences, and of Nursing Family and Community Health School. "Exploring postnatal fatigue : influential factors and management strategies for women." THESIS_CSHS_NFC_Taylor_J.xml, 2003. http://handle.uws.edu.au:8081/1959.7/740.
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Caring for a new child is a significant, demanding, and time consuming role, often associated with increased stress. Postnatal depression is one possible outcome of increased stress and research has highlighted the importance of detecting depression in new mothers. However fatigue a correlate of depression, has only recently become a focus of research among health professionals. Understanding the nature of fatigue and its management within the postnatal period, the focus of this study, may reduce its impact on women’s lives. This longitudinal study explores changes in intensity, physical, mental and emotional dimensions of fatigue, factors associated with higher levels of fatigue, the impact of fatigue on women’s usual activities, and strategies for managing fatigue. Self-administered structured questionnaires gathered data form 504 women at 1, 6, 12 and 24 weeks after birth. Reliable and valid instruments were used to measure the relationship between the defined factors and the outcome of fatigue at the various time points. State anxiety was a consistently strong predictor of fatigue intensity across time and group. Women sought to manage their fatigue by using self-care practices and asking for help from family and friends. This research highlights two issues for health professionals – care of new mothers must include recognition that higher levels of state anxiety are associated with higher levels of postnatal fatigue: ongoing assessment of fatigue and the strategies used to manage it is essential beyond the early postnatal periodDoctor of Philosophy (PhD)
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Juneja, Lokesh Kumar. "Multiaxial fatigue damage model for random amplitude loading histories." Thesis, Virginia Tech, 1992. http://hdl.handle.net/10919/41522.
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In spite of many multiaxial fatigue life prediction methods proposed over decades of
research, no universally accepted approach yet exists. A multiaxial fatigue damage
model developed for approximately proportional random amplitude loading is proposed
in this study. A normal strain based analysis incorporating the multiaxial state
of stress is conducted along a critical orientation assuming a constant strain ratio.
The dominant deformation direction is chosen to be the critical orientation which
is selected with the help of a principal strain histogram generated from the given
multiaxial loading history. The uniaxial cyclic stress-strain curve is modified for the
biaxial state of stress present along the critical orientation for the plane stress conditions.
Modified versions of Morrow's and of Smith, Watson, and Topper's (SWT)
mean-stress models are used to incorporate mean stresses. A maximum shear strain
based analysis is, in addition, conducted to check for the shear dominant fatigue
crack growth possibility along the critical direction. The most damaging maximum
shear strain is chosen after analyzing the in-plane and the two out-of-plane shear
strains.
The minimum of the two life values obtained from SWT model and the shear
strain model is compared with the life estimated by the proposed model with the
modified Morrow's mean stress model. The former is essentially the life predicted by
Socie. The results of the proposed model, as reduced to the uniaxial case, are also
compared with the experimental data obtained by conducting one-channel random
amplitude loading history experiments.
Master of Science
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David, Daniel P. "Resilience as a Protective Factor Against Compassion Fatigue in Trauma Therapists." ScholarWorks, 2011. https://scholarworks.waldenu.edu/dissertations/1027.
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Many adults in the United States experience posttraumatic stress disorder (PTSD) within their lifetimes. Researchers have identified compassion fatigue (CF), which debilitates mental health providers as a result of being exposed to their clients' traumatic experiences, as an occupational hazard. The purpose of this study was to examine whether a correlation exists between the presence of CF and the level of resilience. A confidential survey using the Connors-Davidson Resilience Scale, the Professional Quality of Life Scale Version 5, and a demographic questionnaire were given to graduate-level mental health clinicians who self-identified as routinely working with and/or treating trauma victims in the past 6 months. Participants were recruited from the New England Society for the Treatment of Trauma and Dissociation, the Metropolitan Atlanta Therapists Network, Dallas Chapter NASW listserv, and the Georgia Therapist Network. A multivariate analysis on the collected data was conducted to determine whether a relationship exists between the resilience scale and the subscales of CF within these population samples. According to study findings, there is a correlation between resilience and the 3 compassion fatigue subscales---CF, burnout, and compassion satisfaction. This study may lead to positive social change by helping guide clinicians to find ways to enhance resilience, and therefore, decrease risks of CF.
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Hobson, Ruth M. "Central fatigue during exercise : potential manipulations and limiting factors." Thesis, Loughborough University, 2010. https://dspace.lboro.ac.uk/2134/6975.
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The development of fatigue has been an area of interest to athletes and scientists alike for many years. Often, particularly during prolonged exercise in the heat, there is no obvious peripheral reason for fatigue and the central nervous system is cited as the source. The mechanisms and potential manipulations of this fatigue remain largely unclear. Chapters Three and Four attempted to reduce the transport of the serotonin precursor tryptophan into the brain in order to reduce or delay serotonin synthesis and therefore increase exercise capacity. In Chapter Three branched-chain amino acid drinks were fed before and during prolonged cycling to exhaustion in the heat on two occasions and control drinks were fed on two other occasions. There was no effect of the branched-chain amino acids on exercise capacity and the intra-individual variability in seven of the eight participants was small. One participant did appear to cycle for longer on the branched-chain amino acid trials compared to the control trials. In Chapter Four a 104 g bolus of amino acids, designed to deplete plasma tryptophan concentration, was fed seven hours before a prolonged cycle to exhaustion in the heat. There was no difference in exercise capacity between the tryptophan depletion trial and the control trial in which tryptophan was also ingested. These findings suggest that the delivery of tryptophan to the central nervous system is not the only factor influencing the onset of fatigue. The investigation undertaken in Chapter Five looked at the serotonin transporter density on the blood platelets of current and retired international level athletes competing in either endurance or sprint running events and a sedentary control group. Using the platelet as an accessible and reliable model for the serotonergic neuron, the maximum number of binding sites was assessed using the radio-labelled serotonin reuptake inhibitor [3H]Paroxetine. Those currently training for endurance events had a greater number of binding sites than any of the other groups. This supports previous findings and suggests that endurance training can increase the number of serotonin transporters on blood platelet membranes. During resting heat exposure in Chapter Six, the application of a 1 % menthol solution to the skin of the forearms, back and forehead elicited a warming sensation in some individuals and a cooling sensation in other individuals, but never any change in skin or core temperature nor skin blood flow. A small proportion of individuals did not perceive any change in skin thermal sensation. Chapter Seven applied these findings to a pre-loaded twenty minute exercise performance test in the heat. It was hypothesised that those who perceived a warming effect may perform worse when a menthol solution was applied compared to a control solution and conversely, those who perceived a cooling sensation may perform better with a menthol solution than with a control solution. There was no difference in exercise performance between those who felt a warming sensation and those who felt a cooling sensation. Those who felt a warming sensation felt significantly warmer on the menthol trial than the control trial but this did not affect their performance. However, those who reported a cooling sensation tended to feel cooler on the menthol trial than the control trial, and there was a tendency for an improvement in performance on the menthol trial compared to the control trial. Due to the experimental protocols adopted in this thesis it was possible to assess the reliability of an exercise capacity test compared to an exercise performance test. Chapter Three showed a coefficient of variation of 11.0 ± 11.2 % and Chapter Four showed a 11.5 ± 12.4 % variability for exercise capacity tests. Chapter Seven showed a coefficient of variation in a pre-loaded time-trial exercise performance test of 3.9 ± 9.6 % suggesting that an exercise performance test may be more reliable than an exercise capacity test. However, the aims of an investigation are still likely to be the main factor influencing the choice of protocol. It seems likely that no single mechanism will be responsible for the cessation of exercise. The investigations undertaken in this thesis also highlight many avenues for future exploration.
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Shi, Zhijun. "Predicting fatigue crack growth life in integral metallic skin-stringer panels." Thesis, Cranfield University, 2012. http://dspace.lib.cranfield.ac.uk/handle/1826/7281.
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During the past few years, in comparison to traditional riveted structures, integral metallic skin stringer structures have played more and more important roles in aircraft design due to the fact they are economical and also have the ability to reduce weight. Their wide application in aircraft, especially large integral structures is limited because of the fact that they have shortcomings in damage tolerance performance. Hence, calculating the crack growth lives and improving the damage tolerance performance of integral structures by selecting appropriate materials or choosing rational structures is a critical work. Therefore the purpose of this thesis is to find effective analysis methods of integral metallic skin-stringer panels for the use in engineering. Cont/d.
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Svensson, Tysell Sarah, and Charlotte Andersson. "Compassion Fatigue hos sjuksköterskor : En litteraturöversikt." Thesis, Högskolan Dalarna, Omvårdnad, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:du-27054.
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Bakgrund: För att sjuksköterskor ska kunna tillhandahålla en god personcentrerad vård krävs ett empatiskt förhållningssätt, vilket kan äventyras om sjuksköterskorna drabbas av compassion fatigue. Compassion fatigue är ett relativt nybildat begrepp som handlar om ett tillstånd i form av att vara för trött för att bry sig samt behöva avstå från att bry sig för att skydda sig själv. Detta kan uppkomma hos sjuksköterskor till följd av att vårda svårt sjuka patienter. Inom vård och omsorg är det vanligt med långtidssjukskrivningar på grund av psykisk ohälsa. Syfte: Syftet med denna litteraturöversikt var att beskriva vilka faktorer som påverkar uppkomst av compassion fatigue hos sjuksköterskor samt även beskriva hur sjuksköterskor upplever att drabbas av compassion fatigue. Metod: En litteraturöversikt där resultatet är baserat på 16 artiklar. Resultat: Resultatet delades upp i två huvudkategorier: faktorer som påverkar uppkomst av compassion fatigue samt sjuksköterskors upplevelse av att drabbas av compassion fatigue. Dessa delades sedan upp i subkategorier där de olika faktorerna och upplevelserna presenterades. Slutsats: Sjuksköterskor och annan vårdpersonal samt studenter bör erbjudas utbildning för att bredda kunskapen om compassion fatigue. Det skulle kunna leda till ett lyckat preventivt arbete, vilket i sin tur skulle resultera i färre sjukskrivningar.Background: For nurses to be able to provide a high quality personcentered care it takes an empathetic approach., which can be jeopardized as a consequence of compassion fatigue among nurses. Compassion fatigue is a relatively new term which is about a condition of being too tired to care and needing to abstain from caring to protect oneself. This condition can develop among nurses due to caring for critically ill patients. In healthcare it is common with long term sick leave from psychological illness. Aim: The purpose of this literature review was to describe the factors that can influence the occurance of compassion fatigue among nurses, and to further describe how nurses experience the suffering from compassion fatigue. Method: A literature review where the result is based on 16 articles. Result: The result was divided in to two major categories: factors that influence the occurance of compassion fatigue and nurses experiences of suffering from compassion fatigue. These were then divided in to subcategories where the factors and experiences were presented. Conclusion: Nurses, other healthcare providers and students should be offered education to widen their knowledge about compassion fatigue. This could lead to a successful preventive work, which in turn could result in less sick leaves.
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Aidibi, Ali. "Stress Concentration Factor and Fatigue Life Evaluation in offshore tubular KT-Joints." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2020.
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In the last few decades, offshore field has grown fast especially after the notable development of technologies, explorations of oil and gas in deep water and the high concern of offshore companies in renewable energy mainly Wind Energy. Fatigue damage was noticed as one of the main problems causing failure of offshore structures. The purpose of this research is to focus on the evaluation of Stress Concentration Factor and its influence on Fatigue Life for 2 tubular KT-Joints in offshore Jacket structure using different calculation methods. The work is done by using analytical calculations, mainly Efthymiou’s formulations, and numerical solutions, FEM analysis, using ABAQUS software. As for the analytical formulations, the calculations were done according to the geometrical parameters of each method using excel sheets. As for the numerical model, 2 different types of tubular KT-Joints are present where for each model 5 shell element type, 3 solid element type and 3 solid-with-weld element type models were built on ABAQUS. Meshing was assigned according to International Institute of Welding (IIW) recommendations, 5 types of mesh element, to evaluate the Hot-spot stresses. 23 different types of unitary loading conditions were assigned, 9 axial, 7 in-plane bending moment and 7 out-plane bending moment loads. The extraction of Hot-spot stresses and the evaluation of the Stress Concentration Factor were done using PYTHON scripting and MATLAB. Then, the fatigue damage evaluation for a critical KT tubular joint based on Simplified Fatigue Damage Rule and Local Approaches (Strain Damage Parameter and Stress Damage Parameter) methods were calculated according to the maximum Stress Concentration Factor conducted from DNV and FEA methods. In conclusion, this research helped us to compare different results of Stress Concentration Factor and Fatigue Life using different methods and provided us with a general overview about what to study next in the future.
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Sorensen, Bristol. "Exercise as a contributing factor to complement activation in Chronic Fatigue Syndrome." Connect to online resource, 2007. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3284419.
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Thesis (Ph.D.)--University of Colorado at Boulder, 2007.Source: Dissertation Abstracts International, Volume: 68-11, Section: B, page: 7236. Adviser: James F. Jones. Includes supplementary digital materials.
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Sun, Ye. "NON-CONTACT WEARABLE BODY AREA NETWORK FOR DRIVER HEALTH AND FATIGUE MONITORING." Case Western Reserve University School of Graduate Studies / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=case1405119991.
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Gräns, Hanna. "Transcriptome analysis of patients with chronic fatigue syndrome /." Stockholm, 2005. http://diss.kib.ki.se/2005/91-7140-448-1/.
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Taylor, Janice D. "Exploring postnatal fatigue : influential factors and management strategies for women /." View thesis, 2003. http://library.uws.edu.au/adt-NUWS/public/adt-NUWS20051125.152732/index.html.
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Toulas, N. "Safety factors and risk in fatigue substantiation of helicopter componenets." Thesis, Cranfield University, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.438956.
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Profant, Judith. "Fatigue and sleep complaints in women treated for breast cancer /." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2004. http://wwwlib.umi.com/cr/ucsd/fullcit?p3129934.
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Boussattine, Zaid. "Consequences of the thermal effects generated during fatigue crack growth on the mode one stress intensity factor." Thesis, Paris, ENSAM, 2018. http://www.theses.fr/2018ENAM0047/document.
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Lors du chargement cyclique d’une pièce métallique fissurée, un champ de température hétérogène est créé à la pointe de la fissure. Ce champ de température est dû à trois types de sources de chaleur : (i) la première source est une source de couplage thermoélastique liée à la partie hydrostatique du tenseur des contraintes résultant de la sollicitation mécanique cyclique. Elle fluctue périodiquement dans le temps et l’énergie qui lui est associée est nulle à la fin de chaque cycle de chargement ; (ii) la deuxième source de chaleur est une source dissipative et intrinsèque au comportement du matériau. Elle est reliée au phénomène de l’auto-échauffement dû à la microplasticité dissipée en chaleur dans le matériau à l’échelle microscopique. Elle est positive et s’accumule dans le temps ; (iii) enfin, la troisième source de chaleur a les mêmes origines et propriétés que la deuxième source, mais elle est associée à la plasticité, à l’échelle macroscopique, qui se dissipe en chaleur dans la zone de plasticité cyclique à la pointe de la fissure. En présence de ces trois sources de chaleur, le champ de température résultant génère un champ de contrainte dû au phénomène de la dilatation thermique. Ce nouveau champ des contraintes s’ajoute au champ des contraintes dû au chargement mécanique cyclique, et donc l’état des contraintes sur la fissure est modifié. En conséquence, le facteur d’intensité des contraintes, qui est un paramètre clé dans la modélisation de la propagation des fissures, est modifié. D’où l’objectif de cette thèse qui vise à quantifier les conséquences de ces trois sources de chaleur sur le facteur d’intensité des contraintes, et ce dans le cas d’une fissure longue de fatigueBy subjecting a cracked specimen to a cyclic loading, thermal effects take place and create a heterogeneous temperature field around the crack tip. Those thermal effects are associated with coupling and dissipative heat sources, namely: (i) the heat source due to thermoelastic coupling generated by the hydrostatic part of the stress tensor related to cyclic mechanical loading; (ii) the heat source due to intrinsic dissipation associated with the self-heating phenomena originating from plasticity at the microscopic scale; (iii) and the heat source due to cyclic plasticity, at the macroscopic scale, which occurs in the reverse cyclic plastic zone ahead of the crack tip, and dissipates into heat. The overall heterogeneous temperature field resulting from the heat sources induces a heterogeneous stress field due to thermal expansion phenomena. As a consequence, the stress state over the crack is modified and leads to modify the stress intensity factor, which is a key parameter in modeling fatigue crack growth. Therefore, the aim of this PhD thesis is to quantify the consequences of the heat sources on the stress intensity factor, in the case of a long propagating fatigue crack
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BOUVET, ERIC. "Prevention des facteurs extra-scolaires de fatigue chez l'enfant scolarise : elaboration d'une campagne d'information destinee aux parents dans les ecoles primaires du departement du rhone." Lyon 1, 1990. http://www.theses.fr/1990LYO1M189.
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Ventura, Antunes Fernando Jorge. "Influence of frequency, stress ratio and stress state on fatigue crack growth in nickel base superalloys at elevated temperature." Thesis, University of Portsmouth, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.285929.
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Tucker, David C. "Metabolic factors influencing fatigue during a 90 second maximum muscle contraction." Birmingham, Ala. : University of Alabama at Birmingham, 2009. https://www.mhsl.uab.edu/dt/2009m/tucker.pdf.
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Rahnama, Nader. "Effects of fatigue on selected injury risk factors in Association Football." Thesis, Liverpool John Moores University, 2003. http://researchonline.ljmu.ac.uk/4970/.
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Stubbs, Anthony Pooley. "Fatigue Behaviour of Hot Mix Asphalt for New Zealand Pavement Design." Thesis, University of Canterbury. Civil and Natural Resources Engineering, 2011. http://hdl.handle.net/10092/6520.
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Asphalt’s fatigue and modulus characteristics play an important role in pavement design. Ultimately they govern the required thickness of asphalt to structurally support heavy vehicles. The thickness of the asphalt layer is a major contributor to the cost of construction. In New Zealand, the design of structural asphalt layers has been a problem for some time and gives rise to two areas of concern. First, the present fatigue failure criterion, the Shell fatigue transfer function, which has been adopted from overseas, not only underestimates the fatigue life of the country’s asphalts, but does not accurately characterise the fatigue behaviour of our local asphalt mixes. Consequently, asphalt thicknesses are overdesigned. Second, asphalt’s fatigue behaviour is influenced by numerous factors and therefore can be difficult to characterise. The primary objective of this thesis is to develop fatigue and modulus models, by carrying out fatigue and modulus tests, to characterise the behaviour of two typical New Zealand structural asphalts. Both resilient and stiffness moduli tests were performed at a range of temperatures and loading rates developing moduli master curves, which predict the asphalt’s modulus for any pavement temperature and vehicle speed. A general full factorial experiment was carried out utilising the four-point flexural beam fatigue test. Tests were carried out at different strain levels, temperatures, and loading rates. An analysis of variance showed that the impacts of strain amplitude, temperature, binder type, the interaction of strain amplitude and temperature, and the interaction of strain amplitude and binder type have a significant effect on fatigue behaviour. The developed models, which account for temperature effects give the pavement engineer the ability to undergo a more accurate assessment of fatigue damage than at present for different climatic temperatures demonstrated by using an incremental damage analysis approach. The research shows that with such characterisation for the given pavement’s design life, thinner and less expensive roads can be constructed in New Zealand.
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Warrior, N. A. "The prediction of stress intensity factors by three-dimensional photoelasticity." Thesis, University of Nottingham, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.254390.
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Shohel, Muhammad Shah Newaz. "Panting Fatigue of Welded Steel Tee Details." University of Akron / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=akron1428328220.
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Hannah, Beatrice. "Risk factors associated with high levels of compassion fatigue in foster carers." Thesis, King's College London (University of London), 2016. https://kclpure.kcl.ac.uk/portal/en/theses/structurefunction-relationship-of-the-epidermal-growth-factor-receptor-on-the-cell-surface(87029de4-c941-4271-a63d-66ca21250f53).html.
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CEVOULE, BERNARD. "Implication du facteur passionnel dans la fatigue en planeur." Nice, 1988. http://www.theses.fr/1988NICE6038.
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Jimenez, Acosta Carlos Efren. "Assessment of weld residual stress effects on fatigue crack propagation in ferritic pressure vessel steels." Thesis, University of Manchester, 2016. https://www.research.manchester.ac.uk/portal/en/theses/assessment-of-weld-residual-stress-effects-on-fatigue-crack-propagation-in-ferritic-pressure-vessel-steels(ef8f4e14-3b9c-4f45-876b-dca5d5e9c121).html.
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This project aims to characterise the fatigue behaviour of a crack propagating in a residual stress field changing from tension to compression in the welded zone of a ferritic pressure vessel steel. The fatigue tests were carried out keeping the applied stress intensity factor range constant to determine the role of residual stresses on fatigue crack growth. The residual stresses prior to crack growth were evaluated by X-ray diffraction. The weight function method was used to infer the expected influence of the residual stress on the crack tip in terms of the residual stress intensity factor. Two metrics were used to quantify the crack driving force local to the fatigue crack. Firstly the stress intensity amplitude expressed in terms of the change in the J-integral between maximum and minimum load and secondly the change in the crack opening displacement COD to estimate closure stress intensity factor. The displacement fields local to a fatigue crack were obtained by Digital Image Correlation (DIC) and then analysed by JMAN, an in-house developed algorithm to extract the J-integral based on finite element method and implemented using MATLAB. The difference between the applied stress intensity factor range and the effective crack driving force at the crack tip was determined in order to understand the interaction between the prior residual stresses and crack closure phenomena. Three different R-ratios were evaluated during the experiment (R=0.1, R=0.3 and R=0.5) in order to quantify the effect of residual stress on crack tip stress intensity and crack opening displacement. R-ratio plays a very important role on the fatigue crack growth rate (FCGR): as R increases, FCGR also increases. The COD was assessed by means of the displacements obtained by DIC local to the crack faces. The COD method turned out to be more insightful than the JMAN method for characterising the crack propagation, this is due to the presence of plasticity in the ligament which breaks the non-linear elastic conditions, causing the path-dependence on the J-integral. The FCGR is influenced to a greater degree by the R-ratio and to a lesser degree by the residual stress effect. There is a direct relationship between R and FCGR: as R increases, FCGR also increases, irrespective of the presence of tensile or compressive residual stresses, with the crack closure showing more tendency to occur at low R (i.e. R=0.1) than at high R (i.e. R=0.5). The relationship between R and the residual stress effects on FCGR is inversely proportional: as R increases, the effect of RS decreases.
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Gray, Camille C. "Relationship Between Vocal Fatigue and Physical/Psychological Factors in Prospective Vocal Professionals." Scholar Commons, 2018. https://scholarcommons.usf.edu/etd/7298.
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Background: To date, research has primarily focused on the subjective and objective measurement of vocal fatigue in professional voice users such as teachers and singers. However, these studies have not examined the effects of psychosocial factors (e.g., lack of sleep, emotional distress) leading to vocal fatigue in depth. Much like the professional voice users, students seeking to be professional voice users may face several psychosocial difficulties, may also experience similar vocal demands, and may develop vocal fatigue.
Goal: The purpose of this study is to identify the relationship between psychosocial factors and vocal fatigue in students majoring in Communication Sciences and Disorders.
Methods: During this study, graduate and undergraduate students completed a survey consisting of questions on employment, general health, vocal demands, and several standardized measures, (e.g., Beck’s Depression Inventory, Perceived Stress Scale, and the Vocal Fatigue Index). Vocal fatigue was induced using an adapted LingWAVES vocal loading task (~30-min duration) where participants had to meet a specific intensity goal as well as modify their pitch and voice quality. Recordings of phonation and passage reading were also made pre- and post-loading to evaluate the effects of vocal exertion. The VFI score and two objective measures (fundamental frequency and sound pressure level) were acquired and analyzed in addition to the scores from the surveys.
Results: Results revealed that all students were moderately stressed, while graduate students reported more depression. All students demonstrated vocal fatigue in both subjective and objective outcome measures. Moderate-high correlation between total psychosocial scores and VFI as well as phonation Sound Pressure Level (SPL) were observed.
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Chalder, Trudie. "Factors contributing to the development and maintenance of fatigue in primary care." Thesis, King's College London (University of London), 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.702326.
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Mannion, Anne Frances. "Limiting factors to high intensity exercise : the role of intramuscular pH and skeletal muscle buffering." Thesis, University of Salford, 1990. http://usir.salford.ac.uk/26797/.
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Within the context of a metabolic model of fatigue, formulated from a review of the literature, a decrease in intramuscular pH was identified as a potential limiting factor to the performance of high intensity exercise (HIE). This suggested a role for skeletal muscle buffering (B) in retarding the intramuscular acidosis typically incurred during HIE. Previous studies on human muscle, were largely unable to confirm this role, partly due to the lack of a clearly defined and consistently utilised method of measurement of B. The validity of the procedures currently employed in the determination of B was therefore investigated, revealing that many of the individual differences in B, previously attributed physiological significance, may have originated from inappropriate methodology. In a cross-sectional examination of the vastus lateralis muscle of young, active individuals, low correlations (p<0.05) between the muscle carnosine concentration ([CAR]) and in the 'in vitro B' (Bvit) (r=0.30), and between either [CAR] or Bvit and the % type II fibre area were observed. An elevated Bvit was shown to be of importance in minimising the decrement in pH during HIE, but did not per se permit the accumulation of a higher muscle lactate concentration, or allow for an enhanced HIE performance; these factors were more dependent on the % type II fibre area. The muscle pH, following dynamic HIE was highly variable between individuals, and showed a significant (p<0.05) negative correlation with the % type II fibre area. 16 weeks of isokinetic training of the quadriceps resulted in significant improvements (p<0.05) in dynamic HIE performance with no concomitant improvements in [CAR] or Bvit. The data suggest that the muscle buffer value per se, is not a major limiting factor to HIE, and that rather, the glycolytic capacity and pH tolerance of the muscle may be the more important factors to consider.
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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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Bergman, Erika, and Wiblom Fanny Täckholm. "COMPASSION FATIGUE BLAND SJUKSKÖTERSKOR : EN LITTERATURÖVERSIKT ÖVER FAKTORER SOM KAN BIDRA TILL DESS UTVECKLANDE." Thesis, Ersta Sköndal Bräcke högskola, Institutionen för vårdvetenskap, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:esh:diva-7171.
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BAKGRUND: Det råder idag brist på sjuksköterskor i Sverige, denna brist förväntas öka under de kommande åren till följd av en ökad befolkning i landet. Enligt en undersökning av Statistiska Centralbyrånstatistik från 2014 arbetar en av tio legitimerade sjuksköterskor inte inom vården och en av de största anledningarna till detta är stress. Ett tämligen nbytt begrepp i Sverige, Compassion Fatigue, är ett tillstånd av sekundär traumatisk stress som drabbar personer i vårdgivande roller. Detta tillstånd är relativt outforskat inom svensk sjukvård. SYFTE: Syftet var att belysa faktorer som kan bidra till utvecklandet av compassion fatigue bland sjuksköterskor. METOD: En litteraturöversikt enligt Fribergs metod som baserades på sju studier av kvantitativ metod, två studier av kvalitativ metod och en studie som använt mixad metod. RESULTAT: Resultatet presenteras utifrån fem huvudkategorier: Demografiska faktorer (ålder, kön och civilstånd); Miljörelaterade faktorer (betydelsen av ledarskap, arbetsbelastning och personalomsättning); Yrkesrelaterade faktorer (utbildningsnivå, yrkeserfarenhet, arbetstid och avdelning); Coping (hälsosamma och ohälsosamma hanteringsstrategier); Bekräftelse och stöd (från kollegor, ledning och anhöriga). DISKUSSION:I diskussionen uppmärksammasidentifieras bristen av kunskap om compassion fatigue, bland såväl sjuksköterskor som ledning, som ett betydelsefullt bifynd vilket kan vara en bakomliggande orsak till utvecklandet. Utbildning och stödjande åtgärder kan utformas baserade på Watsons teori om mänsklig omsorg för att förebygga utvecklandet av Compassion Fatigue.BACKGROUND: There is currently a shortage of nursing staff in Sweden. Following on from a population increase, this shortage is expected to increase in upcoming years. According to 2014 statistics, one out of ten licensed nurses do not work within a healthcare setting, and one of the main contributing factors to this is stress. Stress is also the main reason for sick leave among nurses. A fairly new concept in Sweden, Compassion Fatigue, is a condition of secondary traumatic stress, which affects healthcare professionals. This condition is relatively unexplored in Sweden. AIM: The aim of this literature review was to shed light onhighlight factors that may impact on the development of compassion fatigue among nurses. METHOD: A literature review according to Friberg’s method which was based on seven quantitative studies, two qualitative studies and one study of mixed methods. RESULTS: The results are presented based on five main categories: Demographic factors (age, gender and marital status); Environmental factors (importance of leadership, work load and staff turnover); Occupational factors (level of education, professional experience, working hours and department); Coping (healthy and unhealthy management strategies); Acknowledgement and support (from colleagues, management and relatives). DISCUSSION: A lack of knowledge about Compassion Fatigue among nurses as well as management is the main reason for its developtment. Education and supportive measures, based on Watson’s theory of human caring, can be used to prevent Compassion Fatigue.
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Newman, John Andrew. "Life prediction of spot-welds : a fatigue crack growth approach /." Thesis, This resource online, 1996. http://scholar.lib.vt.edu/theses/available/etd-11012008-063415/.
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Dafeeah, Elnour Elnaiem. "A comparative study of the relationship between psychosocial factors and subjective reports of health." Thesis, University of Bristol, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.245364.
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Gillings, Kirsty Louise. "The role of cognitive, emotional and behavioural factors in chronic fatigue and chronic fatigue syndrome/myalgic encephalomyelitis : content, process and therapeutic outcome." Thesis, University of Birmingham, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.486634.
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This thesis is presented in two volumes. In Volume I, the effectiveness of cognitive-behavioural therapy and graded exercise therapy in the management of chronic fatigue are reviewed. The impact of these treatments compared to no treatment and other active therapy is assessed using meta-analytic techniques. The findings indicate that both cognitive-behavioural therapy and graded exercise therapy are effective in reducing fatigue and increasing physical functioning in the short term. Neither approach significantly improved mood disturbance. The findings are discussed with reference to treatment models for chronic fatigue and future research directions are identified. The second paper in Volume I presents an empirical study examining information processing in chronic fatigue syndrome/myalgic encephalomyelitis (CFS/ME). Individuals with CFS/ME, rheumatoid arthritis and healthy controls completed measures of core schema and current mood, in addition to an emotional Stroop task and facial affect recognition task. Stronger core schema were reported by the CFS/ME group. The illness groups both displayed systematic biases in their processing of emotional information. The findings are interpreted with reference to cognitive models of CFS/ME. Volume II contains five individual clinical practice reports completed during Forensic, Child, Older Adult and Learning Disability placements respectively.
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Biegler, Mark Warren. "Determination of stress concentration factors using experimental methods." Thesis, Virginia Polytechnic Institute and State University, 1988. http://hdl.handle.net/10919/80145.
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Several experimental methods are examined for stress concentration factor determination. Tests are performed on a chosen 2-D specimen using strain gages, brittle coating, brittle specimen failure, photoelasticity, and Moire interferometry.
Results are compared to each other and to finite element analysis performed on the same geometry. Strain gaging and photoelasticity were chosen as the best methods for stress concentration factor determination.Master of Science
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Montebello, Claudio. "Analysis of the stress gradient effect in Fretting-Fatigue through a description based on nonlocal intensity factors." Thesis, Université Paris-Saclay (ComUE), 2015. http://www.theses.fr/2015SACLN019/document.
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Nous proposons dans ce manuscrit une nouvelle méthode pour prendre en compte l’effet du gradient en Fretting-fatigue. Les champs mécaniques présents à proximité du front de contact sont décrits à travers des facteurs d’intensité non locaux. L’objectif est d’aboutir à une description du champ de vitesse sous la forme d’une somme de termes exprimés chacun comme le produit d’un facteur d’intensité (Is, Ia, Ic), qui dépend des chargements macroscopiques appliqués à l’ensemble et d’une fonction de forme (ds, da, dc), qui est liée à la géométrie locale du contact. Cette description est obtenue à travers un processus non intrusif de post-processing des résultats obtenus avec des calculs à éléments finis. De plus, elle a été pensée pour être implémentée dans un contexte industriel. En pratique, pour chaque chargement macroscopique et pour chaque géométrie, il est possible de calculer un ensemble de facteurs d’intensité non locaux qui permettent de décrire les champs mécaniques locaux près du front de contact. Cette description non locale a l’avantage d’être (i) indépendante de la géométrie du contact employé et (ii) utilisable dans des modèles à éléments finis utilisés dans l’industrie qui sont caractérisés par des maillages plus grossiers par rapport à ceux utilisés pour étudier le fretting-fatigue dans des milieux académiques. Une étude est menée pour vérifier que les facteurs d’intensité non locaux peuvent être utilisés pour transposer les résultats expérimentaux d’une géométrie à une autreIn this manuscript a new method to describe the stress gradient effect in fretting-fatigue is proposed. It is based on the description of the mechanical fields arising close to the contact edges through nonlocal intensity factors. For this purpose, the kinetic field around the contact ends is partitioned into a summation of multiple terms, each one expressed as the product between intensity factors, Is, Ia, Ic, depending on the macroscopic loads applied to the mechanical assembly, and spatial reference fields, ds, da, dc, depending on the local geometry of the part. This description is obtained through nonintrusive post-processing of FE computation and is conceived in order to be easily implementable in the industrial context. As a matter of fact, for any given macroscopic load and geometry, a set of nonlocal intensity factors is computed that permits to characterize the mechanical fields close to the contact edges. Such nonlocal description has the advantage of being (i) geometry independent so that the nonlocal intensity factors can be used to compare laboratory test with real-scale industrial assembly, (ii) applicable to industrial FE models usually characterized by rougher meshes compared to the ones used to describe fretting-fatigue in the academic context. The procedure is applied to fretting-fatigue test data in order to verify whether the nonlocal intensity factors can be used to transpose experimental results to different contact geometries from the one in which they have been obtained
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Orr, Barry. "Psychological factors in social relationships and home functioning of patients with chronic fatigue syndrome." Thesis, University of Hull, 2008. http://hydra.hull.ac.uk/resources/hull:1679.
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Background: Emotional expressivity has received recent research attention in studying behavioural outcomes, in non-clinical samples and clinical samples alike. However, it has not been tested with chronic fatigue syndrome patients, to see if positive expressivity predicts better social relationships. Secondly, dysfunctional attitudes concerning attainment and achievement, and poor everyday routine, have been associated with poorer functioning in different clinical conditions, such as cancer and diabetes. These have not been examined in chronic fatigue syndrome, for whether they predict worse patient functioning in their home duties. This study primarily aims to explore these relationships. The relationship between attainment/achievement attitudes and routine in this patient group was also explored. Method: This explorative, cross sectional study measured 57 patients' levels of positive expressive behaviour, attainment and achievement attitudes, routine, and levels of social relationship functioning and home functioning via self-report measures. Levels of CFS symptoms and depressive symptoms were also controlled for in each question. Results: Hierarchical regressions indicated positive expressivity did not significantly predict worse or better relationships with friends. Increased positive expressivity did predict worse relationships with family members. Attainment and achievement attitudes did not predict better home functioning, but better routine did. No relationship was found between attitudes and routine. Depressive symptoms predicted greater variance than CFS symptoms in the regressions. Conclusions: Depression appears to be of importance in relationship and home functioning difficulties. Positive expressivity also appears to have a special role for CFS patients, reducing quality of family relationships. Increased routine may help patients to manage their home duties better, but attainment and achievement attitudes appear to make little difference. Such attitudes do not appear to influence routine. Implications of findings for present theory and clinical treatment for patients are discussed, with further research following these findings suggested.
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Armes, Stephanie E. "The Mindfully Attached Therapist: Factors that Predict and Prevent the Development of Compassion Fatigue." UKnowledge, 2014. http://uknowledge.uky.edu/hes_etds/17.
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Characterized as a loss of empathy, compassion fatigue is experienced by many in the helping professions. Also known as secondary traumatic stress, compassion fatigue occurs when those in the helping professions experience trauma through interacting with the traumatic experiences of the people they are helping. Previous literature has found the development of compassion fatigue to be inevitable due to the amount of empathy those professionals must utilize on a daily basis. Mindfulness practices, such as Mindfulness Based Cognitive Therapy (MBCT) and Mindfulness Based Stress Reduction (MBSR) have been found to be a helpful learning tool for those in the helping professions to reduce their levels of stress. Using a convenience sample of 74 therapists, the present study utilized attachment as a framework for exploring factors of predicting and preventing compassion fatigue. Attachment styles in romantic relationships was predicted to be associated with the development of compassion fatigue, while mindfulness levels were predicted to be preventative in the development of compassion fatigue. Findings indicated that levels of compassion fatigue were higher for females, and that higher levels of mindfulness was associated with lower levels of compassion fatigue for both males and females. Implications for therapists, supervisors, and therapists-in-training are addressed.
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Wilson, Flora. "Psychological factors associated with self-reported sleep disturbance in Chronic Fatigue Syndrome and insomnia." Thesis, University of Bath, 2015. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.675711.
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Objectives: Reports of tiredness and poor quality sleep are common to both Chronic Fatigue Syndrome (CFS) and insomnia, despite evidence that sleep structure is not objectively impaired in these groups. Similar vulnerability and maintenance factors have been identified in both conditions, such as perfectionism, unhelpful beliefs and misattributions about symptoms. The aim of this study was to compare CFS and insomnia groups in terms of subjective sleep and fatigue symptoms and associated cognitive factors. Method: Using a cross-sectional design, CFS patients (n=18), community insomnia participants (n=18) and healthy community controls (n=19) were compared on a range of self-report questionnaires, including measures of psychological wellbeing (depression, anxiety, worry), insomnia, sleepiness and fatigue severity, cognitions about sleep and fatigue, and other cognitive variables associated with CFS and insomnia. Results: Between-group analyses identified that CFS and Insomnia participants did not differ significantly on the majority of variables. Compared to controls, both groups reported poorer psychological wellbeing and higher levels of insomnia, sleepiness, and sleep-related cognitions. Both groups also reported elevated perfectionism and unhelpful beliefs about emotions. Compared to the Insomnia group, CFS participants reported higher levels of fatigue, fatigue-related cognitions, and pre-sleep somatic experiences. Conclusions: This study found similarities between CFS and insomnia participants in terms of cognitive processes known to maintain insomnia. This indicates that it may be appropriate to use a transdiagnostic cognitive-behavioural approach to treating sleep disturbance in CFS. The results also indicate the importance of assessing for unhelpful fatigue-related beliefs and pre-sleep somatic complaints when working with the CFS population. Implications for further research are discussed.
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Tarighi, Arash. "Dynamic Behavior and Fatigue Life of Highway Bridges Due to Doubling Heavy Vehicles." FIU Digital Commons, 2015. http://digitalcommons.fiu.edu/etd/1827.
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An increase in the demand for the freight shipping in the United States has been predicted for the near future and Longer Combination Vehicles (LCVs), which can carry more loads in each trip, seem like a good solution for the problem. Currently, utilizing LCVs is not permitted in most states of the US and little research has been conducted on the effects of these heavy vehicles on the roads and bridges. In this research, efforts are made to study these effects by comparing the dynamic and fatigue effects of LCVs with more common trucks.
Ten Steel and prestressed concrete bridges with span lengths ranging from 30’ to 140’ are designed and modeled using the grid system in MATLAB. Additionally, three more real bridges including two single span simply supported steel bridges and a three span continuous steel bridge are modeled using the same MATLAB code. The equations of motion of three LCVs as well as eight other trucks are derived and these vehicles are subjected to different road surface conditions and bumps on the roads and the designed and real bridges. By forming the bridge equations of motion using the mass, stiffness and damping matrices and considering the interaction between the truck and the bridge, the differential equations are solved using the ODE solver in MATLAB and the results of the forces in tires as well as the deflections and moments in the bridge members are obtained.
The results of this study show that for most of the bridges, LCVs result in the smallest values of Dynamic Amplification Factor (DAF) whereas the Single Unit Trucks cause the highest values of DAF when traveling on the bridges. Also in most cases, the values of DAF are observed to be smaller than the 33% threshold suggested by the design code. Additionally, fatigue analysis of the bridges in this study confirms that by replacing the current truck traffic with higher capacity LCVs, in most cases, the remaining fatigue life of the bridge is only slightly decreased which means that taking advantage of these larger vehicles can be a viable option for decision makers.
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Theander, Kersti. "Fatigue, functional status, health and pulmonary rehabilitation in patients with chronic obstructive pulmonary disease." Doctoral thesis, Linköping : Univ, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-8268.
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