A Method for Monitoring Vibrational Fatigue of Structure and Components

A vibration fatigue monitoring system has been developed by Framatome to assess, in real time, the evolution of industrial structures, systems and components lifetime expectancy. Its originality comes from the fact that only one or a few acceleration measurements are necessary to re-construct the complete stress history in the whole structure, including on welds or bolted connections that could not have been directly instrumented. From this stress history, a fatigue analysis with a rainflow counting algorithm is conducted and the cumulative usage factor of each weld or bolt is determined. The remaining life duration is then estimated. The method has been numerically and experimentally validated in that sense that the reconstructed stress histories were successfully compared to direct stress calculations and measurements. The system was then installed on five industrial structures submitted to transient dynamic excitations. It is expected that it will soon find further applications notably in monitoring vibrations induced during power plants transients that may induce some temporary resonance of piping equipment. Finally, the vibration monitoring system can also be combined with a thermal fatigue monitoring system, many of which are already deployed, at least on nuclear power plants, and the reconstructed stresses might include both thermal and mechanical effects. Installing such a fatigue monitoring on a set of sensitive systems and components could be a valuable brick in the present trend of building digital twins of power plants or other industrial structures.

Effect of Shot Peening on the Surface Oxidation of P92 Steel in the Steam Environment at 600°C

A vibration fatigue monitoring system has been developed by Framatome to assess, in real time, the evolution of industrial structures, systems and components lifetime expectancy. Its originality comes from the fact that only one or a few acceleration measurements are necessary to re-construct the complete stress history in the whole structure, including on welds or bolted connections that could not have been directly instrumented. From this stress history, a fatigue analysis with a rainflow counting algorithm is conducted and the cumulative usage factor of each weld or bolt is determined. The remaining life duration is then estimated. The method has been numerically and experimentally validated in that sense that the reconstructed stress histories were successfully compared to direct stress calculations and measurements. The system was then installed on five industrial structures submitted to transient dynamic excitations. It is expected that it will soon find further applications notably in monitoring vibrations induced during power plants transients that may induce some temporary resonance of piping equipment. Finally, the vibration monitoring system can also be combined with a thermal fatigue monitoring system, many of which are already deployed, at least on nuclear power plants, and the reconstructed stresses might include both thermal and mechanical effects. Installing such a fatigue monitoring on a set of sensitive systems and components could be a valuable brick in the present trend of building digital twins of power plants or other industrial structures.

Fatigue Monitoring Through Wearables: A State-of-the-Art Review

The objective measurement of fatigue is of critical relevance in areas such as occupational health and safety as fatigue impairs cognitive and motor performance, thus reducing productivity and increasing the risk of injury. Wearable systems represent highly promising solutions for fatigue monitoring as they enable continuous, long-term monitoring of biomedical signals in unattended settings, with the required comfort and non-intrusiveness. This is a p rerequisite for the development of accurate models for fatigue monitoring in real-time. However, monitoring fatigue through wearable devices imposes unique challenges. To provide an overview of the current state-of-the-art in monitoring variables associated with fatigue via wearables and to detect potential gaps and pitfalls in current knowledge, a systematic review was performed. The Scopus and PubMed databases were searched for articles published in English since 2015, having the terms “fatigue,” “drowsiness,” “vigilance,” or “alertness” in the title, and proposing wearable device-based systems for non-invasive fatigue quantification. Of the 612 retrieved articles, 60 satisfied the inclusion criteria. Included studies were mainly of short duration and conducted in laboratory settings. In general, researchers developed fatigue models based on motion (MOT), electroencephalogram (EEG), photoplethysmogram (PPG), electrocardiogram (ECG), galvanic skin response (GSR), electromyogram (EMG), skin temperature (Tsk), eye movement (EYE), and respiratory (RES) data acquired by wearable devices available in the market. Supervised machine learning models, and more specifically, binary classification models, are predominant among the proposed fatigue quantification approaches. These models were considered to perform very well in detecting fatigue, however, little effort was made to ensure the use of high-quality data during model development. Together, the findings of this review reveal that methodological limitations have hindered the generalizability and real-world applicability of most of the proposed fatigue models. Considerably more work is needed to fully explore the potential of wearables for fatigue quantification as well as to better understand the relationship between fatigue and changes in physiological variables.

Force-Velocity Profile of Competitive Kayakers: Evaluation of a Novel Single Kayak Stroke Test

The assessment of the force-velocity (F-V) profile in athletes may have important applications for training prescription, injury management, and fatigue monitoring. This study aimed to assess whether a novel single kayak stroke test (SKST) is able to provide the F-V relationship variables (maximum force, maximum velocity and maximum power) of competitive kayakers with acceptable reliability and external validity. Six female (age: 20.3 ± 3.7 years) and eight male (age: 20.8 ± 2.4 years) elite kayakers performed the SKST, bench press, bench pull, and short Wingate kayak test. The individual F-V relationships were highly linear [median r (range): left stroke = 0.986 (0.897 - 0.998); right stroke = 0.987 (0.971 - 0.999)]. The reliability of the F-V relationship parameters obtained during the SKST was high (within-session: CV ≤ 4.48% and ICC ≥ 0.93; between-session: CV ≤ 8.06% and ICC ≥ 0.65). The validity of the F-V relationship parameters obtained during the SKST was generally very high for maximum power (r range = 0.825 - 0.975), high for maximum force during both the bench press and the bench pull (r range = 0.751 - 0.831), and high or moderate for maximal velocity during the bench pull (r = 0.770 - 0.829) and the bench press (r = 0.355 - 0.471), respectively. The SKST can be considered a feasible procedure for testing the maximal upper-body muscle mechanical capacities of kayakers.

Method of biocontrol of vehicle driver fatigue

This article describes an example of negligence of drivers transporting passengers and methods of solving it using modern inventions. One of these troubles is driving a car and moving passengers by taxi driver in a tired state. Since not every driver can correctly assess their psycho-physical condition, so to do this, scientists began to create devices for tracking human behavior when he drives vehicle. The purpose of implementing driver fatigue monitoring systems is to ensure road safety and preserve lives and property of citizens. The use of these systems is to facilitate the work of emergency services and taxi company owners, taxi drivers and their passengers. In our article we want to touch on the problem of overwork, specifically taxi drivers, since their work activity is socially significant and non-compliance with the norms of work and rest periods can lead to tragic consequences. Modern taxi drivers often rely on a strong body of car and electronic gadgets in an unexpected situation on the road. Therefore, when driving a car, despite being overworked, they allow themselves to relax beyond the limit and dont react in time if an emergency occurs. We have studied options for implementing driver fatigue monitoring systems and offer to install them on a taxi car.

The Risk Related to the Influence of Sleep Deprivation on the Reliability of Human on the Example of Pilot

The purpose of this publication is to discuss the issues related to the operator sleep deficiency, its effects and the resulting risk. The issue is discussed on the example of a pilot, as a position in which the probability of occurrence of the phenomenon is high, with consequences of its occurrence that can be very severe. Despite the fact, the authors try to present the issues in a universal way enabling reference to a wide spectrum of different types of operators. In the article, concepts such as risk and fatigue are characterized. Furthermore, short and long-term fatigue are discussed, as well as the impact of shift work on human health and reliability. The second part presents methods of fatigue monitoring useful in aviation. The summary emphasizes the need for a holistic approach to the issue of crew fatigue in the management and the need for actions before commencing with work.