Documents disponibles écrits par cet auteur

Experiments and analytical modeling of frequency - targeted laser elastic wave generation and detection in aluminum structures / David Hurley in Journal of engineering mechanics, Vol. 139 N° 3 (Mars 2013) 

Public ISBD [article]  in Journal of engineering mechanics > Vol. 139 N° 3 (Mars 2013) . - pp.248–255. Titre : Experiments and analytical modeling of frequency - targeted laser elastic wave generation and detection in aluminum structures Type de document : texte imprimé Auteurs : David Hurley, Auteur ; Dryver Huston, Auteur Année de publication : 2013 Article en page(s) : pp.248–255. Note générale : Applied mechanics Langues : Anglais (eng) Mots-clés : Inspection  Experimentation  Lasers  Structural  health  monitoring  Aluminum  (material) Résumé : Propagating solid elastic waves forms the basis of multiple nondestructive evaluation (NDE) and structural health monitoring techniques. The majority require direct sensor contact with the material or structure being tested. Conventional NDE methods such as ultrasonic testing have rigorous coupling requirements and limited ranges for damage or defect detection. These requirements and limitations make inspection of large areas or complex geometries slow and cumbersome or altogether impractical. Removing the requirement for contact between the sensor and structure could greatly relax the geometric and size limitations of current elastic wave–based NDE techniques. Laser-based excitation and detection of solid elastic waves are demonstrated capabilities; however, existing laser-based excitation techniques lack the precision and flexibility required by NDE methods that target specific wave modes or frequencies. This proof-of-concept study investigates using a pulsing laser for frequency controlled excitation of elastic waves. Low-frequency experiments demonstrate the principle of matching the excitation laser-pulse frequency to resonances of the tested component. An analytical thermoelastic analysis confirms that low-frequency results extend to higher-frequency ranges commonly used for NDE. The pairing of frequency-tuned, noncontacting laser-based excitation with existing noncontacting laser-based detection equipment could offer new possibilities for NDE of large areas and complex geometries ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29EM.1943-7889.0000515 [article] Experiments and analytical modeling of frequency - targeted laser elastic wave generation and detection in aluminum structures [texte imprimé] / David Hurley, Auteur ; Dryver Huston, Auteur . - 2013 . - pp.248–255. Applied mechanics Langues : Anglais (eng) in Journal of engineering mechanics > Vol. 139 N° 3 (Mars 2013) . - pp.248–255. Mots-clés : Inspection  Experimentation  Lasers  Structural  health  monitoring  Aluminum  (material) Résumé : Propagating solid elastic waves forms the basis of multiple nondestructive evaluation (NDE) and structural health monitoring techniques. The majority require direct sensor contact with the material or structure being tested. Conventional NDE methods such as ultrasonic testing have rigorous coupling requirements and limited ranges for damage or defect detection. These requirements and limitations make inspection of large areas or complex geometries slow and cumbersome or altogether impractical. Removing the requirement for contact between the sensor and structure could greatly relax the geometric and size limitations of current elastic wave–based NDE techniques. Laser-based excitation and detection of solid elastic waves are demonstrated capabilities; however, existing laser-based excitation techniques lack the precision and flexibility required by NDE methods that target specific wave modes or frequencies. This proof-of-concept study investigates using a pulsing laser for frequency controlled excitation of elastic waves. Low-frequency experiments demonstrate the principle of matching the excitation laser-pulse frequency to resonances of the tested component. An analytical thermoelastic analysis confirms that low-frequency results extend to higher-frequency ranges commonly used for NDE. The pairing of frequency-tuned, noncontacting laser-based excitation with existing noncontacting laser-based detection equipment could offer new possibilities for NDE of large areas and complex geometries ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29EM.1943-7889.0000515

Remote monitoring of harsh environments using acoustic emissions / David Hurley in Journal of engineering mechanics, Vol. 139 N° 3 (Mars 2013) 

Public ISBD [article]  in Journal of engineering mechanics > Vol. 139 N° 3 (Mars 2013) . - pp.286–295. Titre : Remote monitoring of harsh environments using acoustic emissions Type de document : texte imprimé Auteurs : David Hurley, Auteur ; David Huston, Auteur ; Douglas Fletcher, Auteur Année de publication : 2013 Article en page(s) : pp.286–295. Note générale : Applied mechanics Langues : Anglais (eng) Mots-clés : Waveguide  Acoustic  Emissions  Ablation Résumé : This paper presents the results of studies assessing waveguided acoustic emission techniques for remotely sensing the condition of structures operating in extreme environments. A particularly acute challenge to sensing in extreme conditions is that the sensor and associated electronics are not sufficiently robust to withstand the structural test conditions. Instead, it is necessary to use signal transduction methods to carry the signal from the structure to a remote and more hospitable sensor location. In the studies reported here an inductively coupled plasma torch creates a simulated environment for the testing of hypervelocity vehicle heat shield materials. Stresses within the material generate acoustic emissions (AEs) that propagate as elastic waves. Waveguides coupled to the sample material and AE sensors allow sample material tests to be monitored remotely. The data were analyzed using multiple statistical methods. The results show that various testing conditions produce repeatable differences in the AE data set, providing evidence that AE testing is sensitive to changes in the thermal degradation of the sample material. AE testing currently offers the potential for real-time in situ monitoring of thermal degradation in laboratory testing conditions and represents progress toward a deployable diagnostic system for aerospace applications. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29EM.1943-7889.0000477 [article] Remote monitoring of harsh environments using acoustic emissions [texte imprimé] / David Hurley, Auteur ; David Huston, Auteur ; Douglas Fletcher, Auteur . - 2013 . - pp.286–295. Applied mechanics Langues : Anglais (eng) in Journal of engineering mechanics > Vol. 139 N° 3 (Mars 2013) . - pp.286–295. Mots-clés : Waveguide  Acoustic  Emissions  Ablation Résumé : This paper presents the results of studies assessing waveguided acoustic emission techniques for remotely sensing the condition of structures operating in extreme environments. A particularly acute challenge to sensing in extreme conditions is that the sensor and associated electronics are not sufficiently robust to withstand the structural test conditions. Instead, it is necessary to use signal transduction methods to carry the signal from the structure to a remote and more hospitable sensor location. In the studies reported here an inductively coupled plasma torch creates a simulated environment for the testing of hypervelocity vehicle heat shield materials. Stresses within the material generate acoustic emissions (AEs) that propagate as elastic waves. Waveguides coupled to the sample material and AE sensors allow sample material tests to be monitored remotely. The data were analyzed using multiple statistical methods. The results show that various testing conditions produce repeatable differences in the AE data set, providing evidence that AE testing is sensitive to changes in the thermal degradation of the sample material. AE testing currently offers the potential for real-time in situ monitoring of thermal degradation in laboratory testing conditions and represents progress toward a deployable diagnostic system for aerospace applications. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29EM.1943-7889.0000477