The Experts below are selected from a list of 75 Experts worldwide ranked by ideXlab platform
Ming Hong - One of the best experts on this subject based on the ideXlab platform.
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locating fatigue Damage using temporal signal features of nonlinear lamb waves
Mechanical Systems and Signal Processing, 2015Co-Authors: Ming Hong, Ye Lu, Hoon Sohn, Zhongqing Su, Xinlin QingAbstract:Abstract The temporal signal features of linear guided waves, as typified by the time-of-flight (ToF), have been exploited intensively for identifying Damage, with proven effectiveness in locating Gross Damage in particular. Upon re-visiting the conventional, ToF-based detection philosophy, the present study extends the use of temporal signal processing to the realm of nonlinear Lamb waves, so as to reap the high sensitivity of nonlinear Lamb waves to small-scale Damage (e.g., fatigue cracks), and the efficacy of temporal signal processing in locating Damage. Nonlinear wave features (i.e., higher-order harmonics) are extracted using networked, miniaturized piezoelectric wafers, and reverted to the time domain for Damage localization. The proposed approach circumvents the deficiencies of using Lamb wave features for evaluating undersized Damage, which are either undiscernible in time-series analysis or lacking in temporal information in spectral analysis. A probabilistic imaging algorithm is introduced to supplement the approach, facilitating the presentation of identification results in an intuitive manner. Through numerical simulation and then experimental validation, two Damage indices (DIs) are comparatively constructed, based, respectively, on linear and nonlinear temporal features of Lamb waves, and used to locate fatigue Damage near a rivet hole of an aluminum plate. Results corroborate the feasibility and effectiveness of using temporal signal features of nonlinear Lamb waves to locate small-scale fatigue Damage, with enhanced accuracy compared with linear ToF-based detection. Taking a step further, a synthesized detection strategy is formulated by amalgamating the two DIs, targeting continuous and adaptive monitoring of Damage from its onset to macroscopic formation.
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fatigue Damage localization using time domain features extracted from nonlinear lamb waves
Proceedings of SPIE, 2014Co-Authors: Ming Hong, Li ChengAbstract:Nonlinear guided waves are sensitive to small-scale fatigue Damage that may hardly be identified by traditional techniques. A characterization method for fatigue Damage is established based on nonlinear Lamb waves in conjunction with the use of a piezoelectric sensor network. Theories on nonlinear Lamb waves for Damage detection are first introduced briefly. Then, the ineffectiveness of using pure frequency-domain information of nonlinear wave signals for locating Damage is discussed. With a revisit to traditional Gross-Damage localization techniques based on the time of flight, the idea of using temporal signal features of nonlinear Lamb waves to locate fatigue Damage is introduced. This process involves a time-frequency analysis that enables the Damage-induced nonlinear signal features, which are either undiscernible in the original time history or uninformative in the frequency spectrum, to be revealed. Subsequently, a finite element modeling technique is employed, accounting for various sources of nonlinearities in a fatigued medium. A piezoelectric sensor network is configured to actively generate and acquire probing Lamb waves that involve Damageinduced nonlinear features. A probability-based diagnostic imaging algorithm is further proposed, presenting results in diagnostic images intuitively. The approach is experimentally verified on a fatigue-Damaged aluminum plate, showing reasonably good accuracy. Compared to existing nonlinear ultrasonics-based inspection techniques, this approach uses a permanently attached sensor network that well accommodates automated online health monitoring; more significantly, it utilizes time-domain information of higher-order harmonics from time-frequency analysis, and demonstrates a great potential for quantitative characterization of small-scale Damage with improved localization accuracy.
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acousto ultrasonics based fatigue Damage characterization linear versus nonlinear signal features
Mechanical Systems and Signal Processing, 2014Co-Authors: Chao Zhou, Ming Hong, Li Cheng, Qiang Wang, Xinlin QingAbstract:Abstract Engineering structures are prone to fatigue Damage over service lifespan, entailing early detection and continuous monitoring of the fatigue Damage from its initiation through growth. A hybrid approach for characterizing fatigue Damage was developed, using two genres of Damage indices constructed based on the linear and the nonlinear features of acousto-ultrasonic waves. The feasibility, precision and practicability of using linear and nonlinear signal features, for quantitatively evaluating multiple barely visible fatigue cracks in a metallic structure, was compared. Miniaturized piezoelectric elements were networked to actively generate and acquire acousto-ultrasonic waves. The active sensing, in conjunction with a diagnostic imaging algorithm, enabled quantitative evaluation of fatigue Damage and facilitated embeddable health monitoring. Results unveiled that the nonlinear features of acousto-ultrasonic waves outperform their linear counterparts in terms of the detectability. Despite the deficiency in perceiving small-scale Damage and the possibility of conveying false alarms, linear features show advantages in noise tolerance and therefore superior practicability. The comparison has consequently motivated an amalgamation of linear and nonlinear features of acousto-ultrasonic waves, targeting the prediction of multi-scale Damage ranging from microscopic fatigue cracks to macroscopic Gross Damage.
Xinlin Qing - One of the best experts on this subject based on the ideXlab platform.
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locating fatigue Damage using temporal signal features of nonlinear lamb waves
Mechanical Systems and Signal Processing, 2015Co-Authors: Ming Hong, Ye Lu, Hoon Sohn, Zhongqing Su, Xinlin QingAbstract:Abstract The temporal signal features of linear guided waves, as typified by the time-of-flight (ToF), have been exploited intensively for identifying Damage, with proven effectiveness in locating Gross Damage in particular. Upon re-visiting the conventional, ToF-based detection philosophy, the present study extends the use of temporal signal processing to the realm of nonlinear Lamb waves, so as to reap the high sensitivity of nonlinear Lamb waves to small-scale Damage (e.g., fatigue cracks), and the efficacy of temporal signal processing in locating Damage. Nonlinear wave features (i.e., higher-order harmonics) are extracted using networked, miniaturized piezoelectric wafers, and reverted to the time domain for Damage localization. The proposed approach circumvents the deficiencies of using Lamb wave features for evaluating undersized Damage, which are either undiscernible in time-series analysis or lacking in temporal information in spectral analysis. A probabilistic imaging algorithm is introduced to supplement the approach, facilitating the presentation of identification results in an intuitive manner. Through numerical simulation and then experimental validation, two Damage indices (DIs) are comparatively constructed, based, respectively, on linear and nonlinear temporal features of Lamb waves, and used to locate fatigue Damage near a rivet hole of an aluminum plate. Results corroborate the feasibility and effectiveness of using temporal signal features of nonlinear Lamb waves to locate small-scale fatigue Damage, with enhanced accuracy compared with linear ToF-based detection. Taking a step further, a synthesized detection strategy is formulated by amalgamating the two DIs, targeting continuous and adaptive monitoring of Damage from its onset to macroscopic formation.
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acousto ultrasonics based fatigue Damage characterization linear versus nonlinear signal features
Mechanical Systems and Signal Processing, 2014Co-Authors: Chao Zhou, Ming Hong, Li Cheng, Qiang Wang, Xinlin QingAbstract:Abstract Engineering structures are prone to fatigue Damage over service lifespan, entailing early detection and continuous monitoring of the fatigue Damage from its initiation through growth. A hybrid approach for characterizing fatigue Damage was developed, using two genres of Damage indices constructed based on the linear and the nonlinear features of acousto-ultrasonic waves. The feasibility, precision and practicability of using linear and nonlinear signal features, for quantitatively evaluating multiple barely visible fatigue cracks in a metallic structure, was compared. Miniaturized piezoelectric elements were networked to actively generate and acquire acousto-ultrasonic waves. The active sensing, in conjunction with a diagnostic imaging algorithm, enabled quantitative evaluation of fatigue Damage and facilitated embeddable health monitoring. Results unveiled that the nonlinear features of acousto-ultrasonic waves outperform their linear counterparts in terms of the detectability. Despite the deficiency in perceiving small-scale Damage and the possibility of conveying false alarms, linear features show advantages in noise tolerance and therefore superior practicability. The comparison has consequently motivated an amalgamation of linear and nonlinear features of acousto-ultrasonic waves, targeting the prediction of multi-scale Damage ranging from microscopic fatigue cracks to macroscopic Gross Damage.
Höfling-lima, Ana Luisa - One of the best experts on this subject based on the ideXlab platform.
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Avaliação da toxicidade na superfície ocular após instilação tópica de doadores de óxido nítrico
Conselho Brasileiro de Oftalmologia, 2015Co-Authors: Cariello, Angelino Julio, Gabriela Freitas Pereira De ,souza, Lowen, Márcia Serva, Marcelo Ganzarolli De ,oliveira, Höfling-lima, Ana LuisaAbstract:PURPOSE: To evaluate the ocular surface toxicity of two nitric oxide donors in ex vivo and in vivo animal models: S-nitrosoglutathione (GSNO) and S-nitroso-N-acetylcysteine (SNAC) in a hydroxypropyl methylcellulose (HPMC) matrix at final concentrations 1.0 and 10.0 mM. METHODS: Ex vivo GSNO and SNAC toxicities were clinically and histologically analyzed using freshly excised pig eyeballs. In vivo experiments were performed with 20 albino rabbits which were randomized into 4 groups (5 animals each): Groups 1 and 2 received instillations of 150 µL of aqueous HPMC solution containing GSNO 1.0 and 10.0 mM, respectively, in one of the eyes; Groups 3 and 4 received instillations of 150 µL of aqueous HPMC solution-containing SNAC 1.0 and 10.0 mM, respectively, in one of the eyes. The contralateral eyes in each group received aqueous HPMC as a control. All animals underwent clinical evaluation on a slit lamp and the eyes were scored according to a modified Draize eye test and were histologically analyzed. RESULTS: Pig eyeballs showed no signs of perforation, erosion, corneal opacity or other Gross Damage. These findings were confirmed by histological analysis. There was no difference between control and treated rabbit eyes according to the Draize eye test score in all groups (p>0.05). All formulations showed a mean score under 1 and were classified as non-irritating. There was no evidence of tissue toxicity in the histological analysis in all animals. CONCLUSION: Aqueous HPMC solutions containing GSNO and SNAC at concentrations up to 10.0 mM do not induce ocular irritation.OBJETIVO: Avaliar a toxidade na superfície ocular de dois compostos doadores de óxido nítrico em modelos ex vivo e in vivo: S-nitrosoglutationa (GSNO) e S-nitroso-N-acetilcisteína (SNAC), em uma matriz de hidroxipropil metilcelulose (HPMC) nas concentrações finais de 1,0 and 10,0 mM. MÉTODOS: As toxicidades de GSNO e SNAC foram avaliadas clinicamente e histologicamente em modelo ex vivo usando globos oculares porcinos recém excisados. Experimentos in vivo foram realizados com 20 coelhos albinos que foram randomizados em 4 grupos (5 animais em cada): Os grupos 1 e 2 receberam instilações de 150 µL de solução aquosa de HPMC contendo GSNO 1,0 e 10,0 mM, respectivamente, em um dos olhos; Os grupos 3 e 4 receberam instilações de 150 µL de solução aquosa de HPMC contendo SNAC 1,0 and 10,0 mM, respectivamente, em um dos olhos. Os olhos contralaterias em cada grupo receberam solução aquosa de HPMC como controle. Todos os animais foram clinicamente avaliados em lâmpada de fenda e os olhos foram pontuados de acordo com o teste de Draize modificado e analisados histologicamente. RESULTADOS: Os globos oculares porcinos não apresentaram sinais de perfuração, erosão, opacidade da córnea ou outros danos graves. Esses resultados foram confirmados pela análise histológica. Não houve diferença entre os olhos dos coelhos tratados e controles de acordo com a pontuação do teste de Draize em todos os grupos (p>0,05). Todas as formulações apresentaram um escore médio menor do que 1 e foram classificadas como não-irritantes. Não houve evidência de toxicidade tecidual nas análises histológicas em todos os animais. CONCLUSÃO: Soluções aquosas de HPMC contendo GSNO e SNAC em concentrações até 10,0 mM não induzem irritação ocular
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Avaliação da toxicidade na superfície ocular após instilação tópica de doadores de óxido nítrico
'FapUNIFESP (SciELO)', 2015Co-Authors: Cariello, Angelino Julio, Gabriela Freitas Pereira De ,souza, Lowen, Márcia Serva, Marcelo Ganzarolli De ,oliveira, Höfling-lima, Ana LuisaAbstract:PURPOSE: To evaluate the ocular surface toxicity of two nitric oxide donors in ex vivo and in vivo animal models: S-nitrosoglutathione (GSNO) and S-nitroso-N-acetylcysteine (SNAC) in a hydroxypropyl methylcellulose (HPMC) matrix at final concentrations 1.0 and 10.0 mM. METHODS: Ex vivo GSNO and SNAC toxicities were clinically and histologically analyzed using freshly excised pig eyeballs. In vivo experiments were performed with 20 albino rabbits which were randomized into 4 groups (5 animals each): Groups 1 and 2 received instillations of 150 µL of aqueous HPMC solution containing GSNO 1.0 and 10.0 mM, respectively, in one of the eyes; Groups 3 and 4 received instillations of 150 µL of aqueous HPMC solution-containing SNAC 1.0 and 10.0 mM, respectively, in one of the eyes. The contralateral eyes in each group received aqueous HPMC as a control. All animals underwent clinical evaluation on a slit lamp and the eyes were scored according to a modified Draize eye test and were histologically analyzed. RESULTS: Pig eyeballs showed no signs of perforation, erosion, corneal opacity or other Gross Damage. These findings were confirmed by histological analysis. There was no difference between control and treated rabbit eyes according to the Draize eye test score in all groups (p>0.05). All formulations showed a mean score under 1 and were classified as non-irritating. There was no evidence of tissue toxicity in the histological analysis in all animals. CONCLUSION: Aqueous HPMC solutions containing GSNO and SNAC at concentrations up to 10.0 mM do not induce ocular irritation.OBJETIVO: Avaliar a toxidade na superfície ocular de dois compostos doadores de óxido nítrico em modelos ex vivo e in vivo: S-nitrosoglutationa (GSNO) e S-nitroso-N-acetilcisteína (SNAC), em uma matriz de hidroxipropil metilcelulose (HPMC) nas concentrações finais de 1,0 and 10,0 mM. MÉTODOS: As toxicidades de GSNO e SNAC foram avaliadas clinicamente e histologicamente em modelo ex vivo usando globos oculares porcinos recém excisados. Experimentos in vivo foram realizados com 20 coelhos albinos que foram randomizados em 4 grupos (5 animais em cada): Os grupos 1 e 2 receberam instilações de 150 µL de solução aquosa de HPMC contendo GSNO 1,0 e 10,0 mM, respectivamente, em um dos olhos; Os grupos 3 e 4 receberam instilações de 150 µL de solução aquosa de HPMC contendo SNAC 1,0 and 10,0 mM, respectivamente, em um dos olhos. Os olhos contralaterias em cada grupo receberam solução aquosa de HPMC como controle. Todos os animais foram clinicamente avaliados em lâmpada de fenda e os olhos foram pontuados de acordo com o teste de Draize modificado e analisados histologicamente. RESULTADOS: Os globos oculares porcinos não apresentaram sinais de perfuração, erosão, opacidade da córnea ou outros danos graves. Esses resultados foram confirmados pela análise histológica. Não houve diferença entre os olhos dos coelhos tratados e controles de acordo com a pontuação do teste de Draize em todos os grupos (p>0,05). Todas as formulações apresentaram um escore médio menor do que 1 e foram classificadas como não-irritantes. Não houve evidência de toxicidade tecidual nas análises histológicas em todos os animais. CONCLUSÃO: Soluções aquosas de HPMC contendo GSNO e SNAC em concentrações até 10,0 mM não induzem irritação ocular.3841Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq
Cariello, Angelino Julio - One of the best experts on this subject based on the ideXlab platform.
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Avaliação da toxicidade na superfície ocular após instilação tópica de doadores de óxido nítrico
Conselho Brasileiro de Oftalmologia, 2015Co-Authors: Cariello, Angelino Julio, Gabriela Freitas Pereira De ,souza, Lowen, Márcia Serva, Marcelo Ganzarolli De ,oliveira, Höfling-lima, Ana LuisaAbstract:PURPOSE: To evaluate the ocular surface toxicity of two nitric oxide donors in ex vivo and in vivo animal models: S-nitrosoglutathione (GSNO) and S-nitroso-N-acetylcysteine (SNAC) in a hydroxypropyl methylcellulose (HPMC) matrix at final concentrations 1.0 and 10.0 mM. METHODS: Ex vivo GSNO and SNAC toxicities were clinically and histologically analyzed using freshly excised pig eyeballs. In vivo experiments were performed with 20 albino rabbits which were randomized into 4 groups (5 animals each): Groups 1 and 2 received instillations of 150 µL of aqueous HPMC solution containing GSNO 1.0 and 10.0 mM, respectively, in one of the eyes; Groups 3 and 4 received instillations of 150 µL of aqueous HPMC solution-containing SNAC 1.0 and 10.0 mM, respectively, in one of the eyes. The contralateral eyes in each group received aqueous HPMC as a control. All animals underwent clinical evaluation on a slit lamp and the eyes were scored according to a modified Draize eye test and were histologically analyzed. RESULTS: Pig eyeballs showed no signs of perforation, erosion, corneal opacity or other Gross Damage. These findings were confirmed by histological analysis. There was no difference between control and treated rabbit eyes according to the Draize eye test score in all groups (p>0.05). All formulations showed a mean score under 1 and were classified as non-irritating. There was no evidence of tissue toxicity in the histological analysis in all animals. CONCLUSION: Aqueous HPMC solutions containing GSNO and SNAC at concentrations up to 10.0 mM do not induce ocular irritation.OBJETIVO: Avaliar a toxidade na superfície ocular de dois compostos doadores de óxido nítrico em modelos ex vivo e in vivo: S-nitrosoglutationa (GSNO) e S-nitroso-N-acetilcisteína (SNAC), em uma matriz de hidroxipropil metilcelulose (HPMC) nas concentrações finais de 1,0 and 10,0 mM. MÉTODOS: As toxicidades de GSNO e SNAC foram avaliadas clinicamente e histologicamente em modelo ex vivo usando globos oculares porcinos recém excisados. Experimentos in vivo foram realizados com 20 coelhos albinos que foram randomizados em 4 grupos (5 animais em cada): Os grupos 1 e 2 receberam instilações de 150 µL de solução aquosa de HPMC contendo GSNO 1,0 e 10,0 mM, respectivamente, em um dos olhos; Os grupos 3 e 4 receberam instilações de 150 µL de solução aquosa de HPMC contendo SNAC 1,0 and 10,0 mM, respectivamente, em um dos olhos. Os olhos contralaterias em cada grupo receberam solução aquosa de HPMC como controle. Todos os animais foram clinicamente avaliados em lâmpada de fenda e os olhos foram pontuados de acordo com o teste de Draize modificado e analisados histologicamente. RESULTADOS: Os globos oculares porcinos não apresentaram sinais de perfuração, erosão, opacidade da córnea ou outros danos graves. Esses resultados foram confirmados pela análise histológica. Não houve diferença entre os olhos dos coelhos tratados e controles de acordo com a pontuação do teste de Draize em todos os grupos (p>0,05). Todas as formulações apresentaram um escore médio menor do que 1 e foram classificadas como não-irritantes. Não houve evidência de toxicidade tecidual nas análises histológicas em todos os animais. CONCLUSÃO: Soluções aquosas de HPMC contendo GSNO e SNAC em concentrações até 10,0 mM não induzem irritação ocular
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Avaliação da toxicidade na superfície ocular após instilação tópica de doadores de óxido nítrico
'FapUNIFESP (SciELO)', 2015Co-Authors: Cariello, Angelino Julio, Gabriela Freitas Pereira De ,souza, Lowen, Márcia Serva, Marcelo Ganzarolli De ,oliveira, Höfling-lima, Ana LuisaAbstract:PURPOSE: To evaluate the ocular surface toxicity of two nitric oxide donors in ex vivo and in vivo animal models: S-nitrosoglutathione (GSNO) and S-nitroso-N-acetylcysteine (SNAC) in a hydroxypropyl methylcellulose (HPMC) matrix at final concentrations 1.0 and 10.0 mM. METHODS: Ex vivo GSNO and SNAC toxicities were clinically and histologically analyzed using freshly excised pig eyeballs. In vivo experiments were performed with 20 albino rabbits which were randomized into 4 groups (5 animals each): Groups 1 and 2 received instillations of 150 µL of aqueous HPMC solution containing GSNO 1.0 and 10.0 mM, respectively, in one of the eyes; Groups 3 and 4 received instillations of 150 µL of aqueous HPMC solution-containing SNAC 1.0 and 10.0 mM, respectively, in one of the eyes. The contralateral eyes in each group received aqueous HPMC as a control. All animals underwent clinical evaluation on a slit lamp and the eyes were scored according to a modified Draize eye test and were histologically analyzed. RESULTS: Pig eyeballs showed no signs of perforation, erosion, corneal opacity or other Gross Damage. These findings were confirmed by histological analysis. There was no difference between control and treated rabbit eyes according to the Draize eye test score in all groups (p>0.05). All formulations showed a mean score under 1 and were classified as non-irritating. There was no evidence of tissue toxicity in the histological analysis in all animals. CONCLUSION: Aqueous HPMC solutions containing GSNO and SNAC at concentrations up to 10.0 mM do not induce ocular irritation.OBJETIVO: Avaliar a toxidade na superfície ocular de dois compostos doadores de óxido nítrico em modelos ex vivo e in vivo: S-nitrosoglutationa (GSNO) e S-nitroso-N-acetilcisteína (SNAC), em uma matriz de hidroxipropil metilcelulose (HPMC) nas concentrações finais de 1,0 and 10,0 mM. MÉTODOS: As toxicidades de GSNO e SNAC foram avaliadas clinicamente e histologicamente em modelo ex vivo usando globos oculares porcinos recém excisados. Experimentos in vivo foram realizados com 20 coelhos albinos que foram randomizados em 4 grupos (5 animais em cada): Os grupos 1 e 2 receberam instilações de 150 µL de solução aquosa de HPMC contendo GSNO 1,0 e 10,0 mM, respectivamente, em um dos olhos; Os grupos 3 e 4 receberam instilações de 150 µL de solução aquosa de HPMC contendo SNAC 1,0 and 10,0 mM, respectivamente, em um dos olhos. Os olhos contralaterias em cada grupo receberam solução aquosa de HPMC como controle. Todos os animais foram clinicamente avaliados em lâmpada de fenda e os olhos foram pontuados de acordo com o teste de Draize modificado e analisados histologicamente. RESULTADOS: Os globos oculares porcinos não apresentaram sinais de perfuração, erosão, opacidade da córnea ou outros danos graves. Esses resultados foram confirmados pela análise histológica. Não houve diferença entre os olhos dos coelhos tratados e controles de acordo com a pontuação do teste de Draize em todos os grupos (p>0,05). Todas as formulações apresentaram um escore médio menor do que 1 e foram classificadas como não-irritantes. Não houve evidência de toxicidade tecidual nas análises histológicas em todos os animais. CONCLUSÃO: Soluções aquosas de HPMC contendo GSNO e SNAC em concentrações até 10,0 mM não induzem irritação ocular.3841Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq
Zhongqing Su - One of the best experts on this subject based on the ideXlab platform.
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characterizing hypervelocity impact hvi induced pitting Damage using active guided ultrasonic waves from linear to nonlinear
Materials, 2017Co-Authors: Kai Wang, Qiang Wang, Cliff J Lissenden, Qingming Zhang, Renrong Long, Zhongqing SuAbstract:Hypervelocity impact (HVI), ubiquitous in low Earth orbit with an impacting velocity in excess of 1 km/s, poses an immense threat to the safety of orbiting spacecraft. Upon penetration of the outer shielding layer of a typical two-layer shielding system, the shattered projectile, together with the jetted materials of the outer shielding material, subsequently impinge the inner shielding layer, to which pitting Damage is introduced. The pitting Damage includes numerous craters and cracks disorderedly scattered over a wide region. Targeting the quantitative evaluation of this sort of Damage (multitudinous Damage within a singular inspection region), a characterization strategy, associating linear with nonlinear features of guided ultrasonic waves, is developed. Linear-wise, changes in the signal features in the time domain (e.g., time-of-flight and energy dissipation) are extracted, for detecting Gross Damage whose characteristic dimensions are comparable to the wavelength of the probing wave; nonlinear-wise, changes in the signal features in the frequency domain (e.g., second harmonic generation), which are proven to be more sensitive than their linear counterparts to small-scale Damage, are explored to characterize HVI-induced pitting Damage scattered in the inner layer. A numerical simulation, supplemented with experimental validation, quantitatively reveals the accumulation of nonlinearity of the guided waves when the waves traverse the pitting Damage, based on which linear and nonlinear Damage indices are proposed. A path-based rapid imaging algorithm, in conjunction with the use of the developed linear and nonlinear indices, is developed, whereby the HVI-induced pitting Damage is characterized in images in terms of the probability of occurrence.
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locating fatigue Damage using temporal signal features of nonlinear lamb waves
Mechanical Systems and Signal Processing, 2015Co-Authors: Ming Hong, Ye Lu, Hoon Sohn, Zhongqing Su, Xinlin QingAbstract:Abstract The temporal signal features of linear guided waves, as typified by the time-of-flight (ToF), have been exploited intensively for identifying Damage, with proven effectiveness in locating Gross Damage in particular. Upon re-visiting the conventional, ToF-based detection philosophy, the present study extends the use of temporal signal processing to the realm of nonlinear Lamb waves, so as to reap the high sensitivity of nonlinear Lamb waves to small-scale Damage (e.g., fatigue cracks), and the efficacy of temporal signal processing in locating Damage. Nonlinear wave features (i.e., higher-order harmonics) are extracted using networked, miniaturized piezoelectric wafers, and reverted to the time domain for Damage localization. The proposed approach circumvents the deficiencies of using Lamb wave features for evaluating undersized Damage, which are either undiscernible in time-series analysis or lacking in temporal information in spectral analysis. A probabilistic imaging algorithm is introduced to supplement the approach, facilitating the presentation of identification results in an intuitive manner. Through numerical simulation and then experimental validation, two Damage indices (DIs) are comparatively constructed, based, respectively, on linear and nonlinear temporal features of Lamb waves, and used to locate fatigue Damage near a rivet hole of an aluminum plate. Results corroborate the feasibility and effectiveness of using temporal signal features of nonlinear Lamb waves to locate small-scale fatigue Damage, with enhanced accuracy compared with linear ToF-based detection. Taking a step further, a synthesized detection strategy is formulated by amalgamating the two DIs, targeting continuous and adaptive monitoring of Damage from its onset to macroscopic formation.
