PSI - Issue 36

M. Karuskevich et al. / Procedia Structural Integrity 36 (2022) 92–99 M. Karuskevich, T. Maslak, Ie. Gavrylov et al. / Structural Integrity Procedia 00 (2021) 000 – 000

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Application of the Finite Elements Analysis allows for the providing the compromise in the two controversial tasks: a) increase of the sensitivity to ensure the fracture of the overstress indicator at the unallowable strain; b) prevention of the overstress indicator loss of the stability under the compression. The fracture of the overstress indicator must occur when the structural stress reaches the elastic limit for the structural material. For indicator made of the same metal as the surveyed structural element, it means the local multiplication of s tress for “necked” section of the indicator must be equal to the ratio of tensile strength to the yield strength . If the indicator and structural element of the aircraft are made of different metals the simple calculations are required based on the relation of their mechanical properties, considering the same general strain of the structural element and indicator on the base equal to the distance between the indicator’s attachments points. Transmitting overstress indicator’s signal into the cabin doesn’t require very much sophisticated arrangement. The direct current used in the onboard system can be used to supply information regarding the state of the indicator. The electrical system on most aeroplanes is either a 14- or 28-volt system. 14-volt systems have 12-volt batteries. 28-volt systems utilize 24-volt batteries. The Overstress indicator is incorporated into the special electrical circuit with relays, providing green and red lamps light. As it is known from the light aeroplanes design there is enough space for upgrading instrument panel by the installation Overstress Indicator indicating lamps. 8. Conclusion Fatigue and overstress of the principal structural element is a crucial problem for all categories of aircraft. Light aircraft have limited opportunities for the application of advanced Structural Health Monitoring Systems. That is why the autonomous Surface Relief Fatigue Indicator (SRFI) may be considered as a reliable tool for fatigue monitoring. Light aircraft due to the action of the unallowable accelerations in manoeuvers meet the overstress conditions for the components. The excessive stresses can lead to the deformation of the structure, loss of the aerodynamic characteristics and even to an aircraft crash. The overstress can be revealed by the simple proposed device, called here Overstress Indicator. It allows for the prevention of the flight with damaged structure, thus increases the safety of the operation. Acknowledgments The presented research is carried out due to the memorandums of understanding between National Aviation University (Ukraine) and Bydgoszcz University of Science and Technology (Poland). References Aero-news, 2015: http://www.aero-news.net/index.cfm?do=main.textpost&id=7ba6dcbb-aeb7-41b2-a8e1-3754e6ff94b9 Aviation Investigation Report In-flight Break-up Cessna 210L Centurion C-GPMC. 2001. Report Number A01O0165. Easy Access Rules for Light Sport Aeroplanes (CS-LSA) (Amendment 1) 2018, EASA eRules, 24. Karuskevich M., Ignatovich S., Maslak T., Karuskevich O., Pejkowski Ł., Kurdel P. 2020. Fatigue and overstress i ndicators for ultralight and light aircraft Fatigue Fract Eng Mater Struct 44 (2), 595-598. Karuskevich, M., Karuskevich, O., Maslak, T., Schepak, S. 2012. Extrusion/intrusion structures as quantitative indicators of accumulated fatigue damage. Int J Fatigue 39, 116-121. Karuskevich, M.V., Ignatovich, S.R., Maslak, Т .P. , Menou, A. Maruschak, P. О ., Panin, S.V., Berto, F. 2016. Multi-purpose fatigue sensor. Part 1. Uniaxial and multiaxial fatigue. “Frattura ed Integrita Strutturale” 38, 198 -204. Karuskevich, M.V., Ignatovich, S.R., Maslak, Т .P. , Menou, A. Maruschak, P. О ., Panin, S.V., Berto, F. 2016. Multi-purpose fatigue sensor. Part 2. Physical backgrounds for damages accumulation and parameters of their assessment. “ Frattura ed Integrita Strutturale ” 38 , 205-214. Man, J., Obrtlik K., Polak V. 2009. Extrusions and intrusions in fatigued metals. Part 1. State of the art and history. Philosophical Magazine 89(16) 1295 – 1336. Pejkowski, Ł., Karuskevich, M. Maslak, T. 2019. Extrusion/intrusion structure as a fatigue indicator for uniaxial and multiaxial loading. Fatigue Fract Eng Mater Struct. 42 (10), 2315-2324. TomarkAero: http://tomarkaero.com/en/