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Kamil Kowalczyk - One of the best experts on this subject based on the ideXlab platform.
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perspective of structural health monitoring for military aviation in poland
International Committee on Aeronautical Fatigue, 2019Co-Authors: Krzysztof Dragan, Artur Kurnyta, Michal Dziendzikowski, Kamil KowalczykAbstract:About 40 years have passed from introducing non-destructive testing inspections (NDI) as an inherent component of damage tolerant Approach in order to ensure structural integrity of aircrafts. Over the years, non-destructive testing (NDT) methods became very accurate and reliable in damage detection and assessment, allowing to achieve very high level of safety in the aerospace. However, still there are some issues of this aircraft design paradigm which need to be addressed in the future. First, NDI are scheduled based on assumed or statistically represented loads spectrum, which doesn’t necessarily fit to the way which a given aircraft is operated. This jeopardize the safety, but also is connected with not scheduled inspections, whose costs are much higher than regular ones. In fact, the fraction of unexpected NDI prevail over scheduled inspections. Furthermore, application of new lightweight materials, e.g. composites, introduces new damage evolution pathways, making it difficult to use low cost NDT techniques like visual testing, which account for about 60% of overall NDI. Therefore, there is a strong need from the industry sector to introduce Structural Health Monitoring (SHM) and Operational Load Monitoring (OLM) systems, based on sensors permanently integrated with the aircraft structure. Application of such systems would definitely increase safety, especially when considering hardly accessible ‘hot-spots’, but it could also save up to 50% of necessary inspections time depending on the aircraft type. Furthermore, possessing the knowledge about the current state of an aircraft as well as the way it is used, would allow to predict its further performance and determine the optimal time for its overhauls. Clearly, damage detection and damage assessment capabilities of SHM systems, e.g. expressed in terms of PoD curves, are the most important ones. However, from the cost analysis perspective, also a very important property of SHM systems is their false calls ratio. Damage indication by SHM system will be verified with classical NDT methods, at least at their early stage of development, which would increase the number of unplanned NDI and could rise aircraft maintenance costs, if there would be too much false positive findings. Both, the improvement of damage detection capabilities as well as the reduction of false calls ratio of SHM systems, are as much important for their applicability.
Krzysztof Dragan - One of the best experts on this subject based on the ideXlab platform.
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perspective of structural health monitoring for military aviation in poland
International Committee on Aeronautical Fatigue, 2019Co-Authors: Krzysztof Dragan, Artur Kurnyta, Michal Dziendzikowski, Kamil KowalczykAbstract:About 40 years have passed from introducing non-destructive testing inspections (NDI) as an inherent component of damage tolerant Approach in order to ensure structural integrity of aircrafts. Over the years, non-destructive testing (NDT) methods became very accurate and reliable in damage detection and assessment, allowing to achieve very high level of safety in the aerospace. However, still there are some issues of this aircraft design paradigm which need to be addressed in the future. First, NDI are scheduled based on assumed or statistically represented loads spectrum, which doesn’t necessarily fit to the way which a given aircraft is operated. This jeopardize the safety, but also is connected with not scheduled inspections, whose costs are much higher than regular ones. In fact, the fraction of unexpected NDI prevail over scheduled inspections. Furthermore, application of new lightweight materials, e.g. composites, introduces new damage evolution pathways, making it difficult to use low cost NDT techniques like visual testing, which account for about 60% of overall NDI. Therefore, there is a strong need from the industry sector to introduce Structural Health Monitoring (SHM) and Operational Load Monitoring (OLM) systems, based on sensors permanently integrated with the aircraft structure. Application of such systems would definitely increase safety, especially when considering hardly accessible ‘hot-spots’, but it could also save up to 50% of necessary inspections time depending on the aircraft type. Furthermore, possessing the knowledge about the current state of an aircraft as well as the way it is used, would allow to predict its further performance and determine the optimal time for its overhauls. Clearly, damage detection and damage assessment capabilities of SHM systems, e.g. expressed in terms of PoD curves, are the most important ones. However, from the cost analysis perspective, also a very important property of SHM systems is their false calls ratio. Damage indication by SHM system will be verified with classical NDT methods, at least at their early stage of development, which would increase the number of unplanned NDI and could rise aircraft maintenance costs, if there would be too much false positive findings. Both, the improvement of damage detection capabilities as well as the reduction of false calls ratio of SHM systems, are as much important for their applicability.
Fabrizio Ricci - One of the best experts on this subject based on the ideXlab platform.
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damage localization in composite structures using a guided waves based multi parameter Approach
Aerospace, 2018Co-Authors: Vittorio Memmolo, N D Boffa, L Maio, Ernesto Monaco, Fabrizio RicciAbstract:Aerospace vehicles are demanded to withstand harsh conditions with a low weight impact. Composites have been increasingly adopted to meet such performances but they are affected by sudden and barely visible failures when subjected to low velocity impacts. The design criteria and the maintenance tasks in a damage tolerant Approach are unavoidably compromised. Structural Health Monitoring is expected to avoid typical accommodations employed during design and lifetime management by achieving a cost-effective and on condition maintenance. This paper describes the use of guided ultrasonic waves excited and sensed by permanently attached piezoelectric transducers for detection and localization of unforeseen and hidden flaws in composite structures. A composite stiffened structures designed for real scale components is investigated to test a multi-parameter detection technique capable of predicting different wave features affected by hidden failures to detect any possible change in the structure. Usually, propagation behavior is exploited to detect changes in the waveguide focusing on the analysis of an intrinsic feature of the propagating wave. Numerical simulations and measurements carried out on a real-scale aircraft structure demonstrate that increasing the observed characteristics improves the result making efficient the diagnosis. Furthermore, it is shown that accounting a multi-parameter analysis of ultrasonic data enhances the localization reliability making use of the same reconstruction algorithm with data fusion Approach while facing with different kind of damages.
J D Achenbach - One of the best experts on this subject based on the ideXlab platform.
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optimization of inspection schedule for a surface breaking crack subject to fatigue loading
Probabilistic Engineering Mechanics, 2007Co-Authors: Salil S Kulkarni, J D AchenbachAbstract:Abstract Inspections play an essential role in the damage tolerance Approach to control fatigue damage. In this paper a method is presented to optimize the cost-effectiveness of inspection scheduling for single and multiple inspections during the expected lifetime. Detailed results are given for a surface-breaking crack of depth a in a cyclic tension field. The original crack depth is treated as a random variable with a known probability density function. The crack growth is governed by the Paris law, and the inspection technique has a known probability of detection. The component fails when the crack depth reaches a critical value a cr . As a part of the Damage-Tolerant Approach, the component is replaced only when the depth of the detected crack is larger than a pre-defined value a r . For a pre-determined number of cycles that defines the expected lifetime the optimal number of cycles for the inspection scheduling has been obtained by minimizing a total cost function. The total cost function is the sum of the cost functions for failure, component replacement and inspection. These functions have been expressed is terms of the relevant probabilities. Analytical and numerical results are given for one, two and multiple inspections. These results show the effects of the magnitude of a r , and the probability of detection (POD) of the inspection technique on the optimum schedule of inspections.
Artur Kurnyta - One of the best experts on this subject based on the ideXlab platform.
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perspective of structural health monitoring for military aviation in poland
International Committee on Aeronautical Fatigue, 2019Co-Authors: Krzysztof Dragan, Artur Kurnyta, Michal Dziendzikowski, Kamil KowalczykAbstract:About 40 years have passed from introducing non-destructive testing inspections (NDI) as an inherent component of damage tolerant Approach in order to ensure structural integrity of aircrafts. Over the years, non-destructive testing (NDT) methods became very accurate and reliable in damage detection and assessment, allowing to achieve very high level of safety in the aerospace. However, still there are some issues of this aircraft design paradigm which need to be addressed in the future. First, NDI are scheduled based on assumed or statistically represented loads spectrum, which doesn’t necessarily fit to the way which a given aircraft is operated. This jeopardize the safety, but also is connected with not scheduled inspections, whose costs are much higher than regular ones. In fact, the fraction of unexpected NDI prevail over scheduled inspections. Furthermore, application of new lightweight materials, e.g. composites, introduces new damage evolution pathways, making it difficult to use low cost NDT techniques like visual testing, which account for about 60% of overall NDI. Therefore, there is a strong need from the industry sector to introduce Structural Health Monitoring (SHM) and Operational Load Monitoring (OLM) systems, based on sensors permanently integrated with the aircraft structure. Application of such systems would definitely increase safety, especially when considering hardly accessible ‘hot-spots’, but it could also save up to 50% of necessary inspections time depending on the aircraft type. Furthermore, possessing the knowledge about the current state of an aircraft as well as the way it is used, would allow to predict its further performance and determine the optimal time for its overhauls. Clearly, damage detection and damage assessment capabilities of SHM systems, e.g. expressed in terms of PoD curves, are the most important ones. However, from the cost analysis perspective, also a very important property of SHM systems is their false calls ratio. Damage indication by SHM system will be verified with classical NDT methods, at least at their early stage of development, which would increase the number of unplanned NDI and could rise aircraft maintenance costs, if there would be too much false positive findings. Both, the improvement of damage detection capabilities as well as the reduction of false calls ratio of SHM systems, are as much important for their applicability.
