Assessment of the limits of signs of health and usage monitoring system for helicopter transmission

Nedel’ko, D. V.; Urbahs, Aleksandrs; Turko, Vladislav; Urbaha, Margarita; Carjova, Kristīne; Nagaraj, Pavithra

doi:10.1016/j.procs.2019.01.131

Cited by 8 publications

(6 citation statements)

References 2 publications

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“…This integrated method allows monitoring a rather extensive area free of NDT Operator in the online regime [14]. When diagnostic signs of incipient fracture appear, it becomes possible for the Operator to periodically use other methods of instrumental control of a suspicious area, but already in specific places of destruction [15], [16].…”

Section: Resultsmentioning

confidence: 99%

Three Stages of Composite Specimen Destruction in Static Failure

Urbaha

Agafonovs

Turko

et al. 2021

Latvian Journal of Physics and Technical Sciences

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The paper presents the results of standard specimen fracture made of anisotropic carbon fiber plastic with an epoxy matrix. Static stepwise loading of the specimen was carried out on an Instron 8801 testing machine to determine the characteristics of ductile fracture G1C in the first mode in accordance with ASTM D5528. During loading, the parameters of acoustic emission (AE) signals, such as AE impulse amplitudes and their energy were synchronously recorded. At the same time, the magnitude of the opening and the growth of the crack initiated by the artificial cut at the end of the specimen were recorded. According to the analysis of the acoustic emission signals, three zones with different G1C behaviour were identified: initial crack propagation, its stationary growth and accelerated fracture of the specimen. The zonal character of the change in the acoustic emission signals made it possible to determine the energy of the acoustic emission signals as diagnostic evidence for the onset of rapid destruction of the specimen. The amplitude of the AE-signals in the zones, however, remained constant. Online monitoring of changes in the energy of acoustic emission signals will prevent the onset of rapid destruction of an object in places of its deformations. The paper does not aim at defining G1C as usual. It presents the investigation of the fracture stages for a composite material using an acoustic emission method.

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Section: Resultsmentioning

confidence: 99%

Three Stages of Composite Specimen Destruction in Static Failure

Urbaha

Agafonovs

Turko

et al. 2021

Latvian Journal of Physics and Technical Sciences

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“…So we can draw a conclusion that as single compression and symmetrical loads applied ahead the regular cyclic loads have the most damaging effect to fatigue live of specimens. It is worth pointing out that the compression single peak loads simulate the impact (impulse) influence to the design and its structure elements in working (operational) condition [12].…”

Section: Resultsmentioning

confidence: 99%

Experimental evaluation of static and fatigue strength of aluminium-based structural metallic alloys

Urbaha

Turko

Agafonovs

et al. 2020

19th International Scientific Conference Engineering for Rural Development Proceedings

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The paper presents the results of the research for the static and fatigue strength of specimens made of aluminum-based high-strength alloys В95 and 1163. Specimens of different thickness sized 220 mm х 36 mm with a hole in the middle with a diameter of 6 mm have been loaded by using INSTRON 8801 and 8802 testing machines. The total sample volume worked out 400 specimens. The fatigue tests were carried out at cyclic regular loading with a frequency of 5 Hz. For the estimation of the effect of single-shot tensile and compressive static peak loads have been applied in blocks. S-N fatigue curves for various configurations of loading blocks have been plotted based on the results of the fatigue tests, the influence of various loading blocks on fatigue life have been compared for samples of two aluminum alloys.

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“…Considering the complex shafting structural designs of helicopters, any slight changes in the relative positions of shafting will lead to changes in the transmission characteristics of the entire transmission system, which will accelerate the wear of support bearings, shorten the service life of the bearings, and greatly impact the tooth surface friction at the gear meshing. As a result, vibration impacts will be produced which will negatively affect the performances of the transmission systems [11,12]. Due to the aforementioned tendencies, the transmission systems of helicopters may be subjected to additional excitation force, which will significantly reduce the working life of the transmission systems.…”

Section: Introductionsmentioning

confidence: 99%

An Analysis of the Gear Meshing Characteristics of the Main Planetary Gear Trains of Helicopters Undergoing Shafting Position Changes

Jiang

Dengrong

et al. 2021

International Journal of Aerospace Engineering

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The complex three-shaft three-reducer structural designs of helicopter transmission systems are prone to changes in the relative positions of shafting under the conditions of main rotor and tail rotor loads. These changes will affect the transmission characteristics of the entire transmission system. In this study, the planetary gear trains of helicopters were examined. Due to the fact that these structures are considered to be the most representative structures of the main reducers of helicopters, they were selected as the study objects for the purpose of examining the meshing characteristics of planetary gear trains when the relative positions of the shafting changed due to the position changes of the main rotor shafts under variable load conditions. It was found that by embedding the comprehensive time-varying meshing stiffness values of the main rotor shafts at different positions, a dynamic model of the relative position changes of the planetary gear trains could be established. Then, combined with the multibody dynamics software, the meshing characteristics of the sun gears, and the planetary gears, the planetary gears and the inner ring gears were simulated and analyzed under different inclinations and offsets of the shafting. The results obtained in this study revealed the following: (1) the average meshing force of the gears increased with the increases in the angle inclinations, and the meshing force between the sun gears and the planetary gears increased faster than the meshing force between the planetary gears and the inner ring gears. It was observed that during the changes in the shafting tilt positions, obvious side frequency signals had appeared around the peak of the meshing frequency in the spectrum. Then, with the continuous increases in the tilt position, the peak was gradually submerged; (2) the average meshing force of the gears increased with the increases in the offset, and the increasing trend of the meshing force between the sun gears and the planetary gears was similar to that observed between the planetary gears and the inner ring gears. It was found that when the shafting offset position changed, there were obvious first and second frequency doubling in the spectrum; (3) the mass center orbit radii of the sun gears increased with the increases in the shafting position changes, and the changes in the angular tilt position were found to have greater influencing effects on the mass center orbit radii of the sun gears than the changes in the offset positions. This study’s research findings will provide a theoretical basis for future operational status monitoring of the main transmission systems of helicopters and are of major significance for improvements in the operational stability of helicopter transmission systems, which will potentially ensure safe and efficient operations.

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Assessment of the limits of signs of health and usage monitoring system for helicopter transmission

Cited by 8 publications

References 2 publications

Three Stages of Composite Specimen Destruction in Static Failure

Three Stages of Composite Specimen Destruction in Static Failure

Experimental evaluation of static and fatigue strength of aluminium-based structural metallic alloys

An Analysis of the Gear Meshing Characteristics of the Main Planetary Gear Trains of Helicopters Undergoing Shafting Position Changes

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