21 research outputs found
Low cost infrared thermography for automated crack monitoring in fatigue testing
No full textThe potential of using infrared thermography in the assessment of crack-tip parameters is described. The use of microbolometers is studied specifically to establish their suitability for use in thermoelastic stress analysis (TSA) for establishing the crack-tip parameters and for automatically monitoring crack growth using temperature measurement. To compare the behaviour of the two types of infrared cameras a camera model is devised, which is used to predict the thermoelastic response. A new automatic crack growth monitoring approach is developed based on the temperature measurement from the raw thermal data collected using the microbolometer. The thermoelastic response model and the crack monitoring procedure are demonstrated on 316 L stainless steel single edge notch tension (SENT) specimens. Cracks were established in the specimens, grown and monitored using both types of infrared detector. The procedure is validated using measurements from the photon detector and it is shown that accurate stress intensity factors (SIFs) can be obtained from growing cracks using directly the live readings from the microbolometer. The procedure provides a new means for non-contact measurements in fatigue testing, establishing crack growth rate and the SIFs with the potential for actuator control.</p
Sources of Variation in JIC Measurements of Ductile Fracture Toughness Using Unloading Compliance
No full textAbstractThis paper presents an evaluation of calculative and experimental effects which can lead to inter- and intra-laboratory variation in toughness measurement. Physical tests were conducted on specimens of an austenitic steel, and the effects of realistic test conditions are demonstrated. Different (permitted) calculation methods produce a significant effect which has been evaluated both for the real data and for an idealised model dataset in development for use in international standards.Ductile fracture of metals has been a topic of increasing interest over several years, primarily due to growing investment in many parts of the energy industry. This has coincided with several international testing standards, in this area, coming up for periodic review. Among efforts to clarify standard test and calculation methods it became clear that differences between methods which are all deemed “acceptable” (and are necessary for different test scenarios) can lead to significant variation in results when applied to comparable tests
Application of strain-controlled fatigue testing methods to polymer matrix composites
No full textAbstractThis paper presents a short investigation of the benefits of non-contact strain measurement for monitoring and control of fatigue tests on composites. Recent developments in measurement technology offer the means to effectively measure both axial and transverse strain, instantly, throughout cyclic and highly dynamic tests. Several test scenarios are examined which demonstrate potential benefits of current state-of-the-art video extensometry, for strain controlled fatigue tests on thermoplastic composites.Live extensometry enables continuous monitoring and live calculations throughout the test and provides the option to automatically collect additional data for loading cycles with anomalous behaviour. It also allows a good control system to safely apply accurately strain-controlled loading of specimens. Digital image correlation techniques can offer complimentary information on the full-field strain behaviour of a specimen, but the data processing and storage requirements are considerably too large for live or continuous measurements during fatigue tests.Composites fatigue investigations, to date, have generally been focused on high cycle fatigue, typically under sinusoidal stress-controlled conditions. The authors propose that there is a growing need to understand composite behaviour, at well-defined strain-rates and under conditions of occasional, non-catastrophic, overload; furthermore that non-contact extensometry is an important enabling technology for such investigations
Les marqueurs de prolifération en oncologie vétérinaire : applications à l'étude pronostique du mastocytome cutané canin
No full textLe mastocytome cutané représente un type tumoral dominant de la cancérologie du chien mais demeure l'une des tumeurs canines au comportement clinique les plus imprévisibles. L'auteur évalue dans une étude rétrospective portant sur 120 chiens porteurs de mastocytome cutané, la valeur pronostique de la détection immunohistochimique des marqueurs de prolifération PCNA et Ki-67. Il montre que la détermination de l'expression de l'antigène Ki-67 permet de prédire avec une grande fiabilité l'évolution clinique post-chirurgicale de ce type tumoral
Mort ne au 4 Avril
No full textHip hop song sung in English, French and Wolof, accompanied by traditional Senegalese kora and tama musical instruments, as well as Western instrument
Fuck le 6 theme
No full textHip hop song sung in English, French and Wolof, accompanied by traditional Senegalese kora and tama musical instruments, as well as Western instrument
Wow wow
No full textHip hop song sung in English, French and Wolof, accompanied by traditional Senegalese kora and tama musical instruments, as well as Western instrument
Libre Ego
No full textHip hop song sung in English, French and Wolof, accompanied by traditional Senegalese kora and tama musical instruments, as well as Western instrument
Na gueneu metti
No full textHip hop song sung in English, French and Wolof, accompanied by traditional Senegalese kora and tama musical instruments, as well as Western instrument
PBS 2000
No full textHip hop song sung in English, French and Wolof, accompanied by traditional Senegalese kora and tama musical instruments, as well as Western instrument
