New Technology | GRGTEST Successfully Developed Fault Analysis Technology For Main Reducers Based On Sound Signals

The main reducer is one of the most important components of the helicopter transmission system, responsible for power steering and variable speed tasks. It is connected to the engine, main rotor, hydraulic system, etc., and affects multiple key performance of the helicopter. Under long-term mission execution, the components of the main reducer will inevitably experience fatigue and aging, which can easily lead to malfunctions and cause flight accidents. In order to timely warn of main reducer faults and ensure helicopter flight safety, the Institute of Radio and Television Metrology Reliability and Environmental Engineering has established a special research group to carry out research on main reducer fault analysis technology based on sound signals, ensuring helicopter flight safety.

The main reducer is now fatigued, and helicopters are prone to accidents
According to statistics, over 50% of helicopter flight accidents caused by mechanical failures can be attributed to the failure of the main moving components (rotor system, engine, and transmission system). Among them, the maintenance cost of the transmission system accounts for about 30% of the total maintenance cost and is a key monitoring and maintenance object.

The main reducer, as one of the most important components of the transmission system, is mainly composed of a shaft, bearings, and gears. During the work process, due to internal factors such as gaps, friction, and interaction forces between components, as well as external factors such as material defects, manufacturing and assembly errors, and harsh working environments, the main reducer will inevitably experience fatigue and aging during long-term operation. Once a malfunction occurs during helicopter flight, it will threaten normal flight and personnel safety, bringing great losses and unpredictable impacts.

【1】 Yuan Zhiwen, Zhao Yun, Jin Xiaoqiang, etc Testability modeling analysis of helicopter transmission system based on TEAMS [J] China Science and Technology Information, 2021 (5): 24-26 DOI:10.3969/j.issn.1001-8972.2021.05.004.

【2】 Ding Wenqiang Overview of the Development of Helicopter Transmission Systems [J] Aviation Power, 2018 (3): 65

Fault mode "audible" acoustic signal "visible"

At present, the fault diagnosis of the main reducer is mostly based on the vibration signals collected by sensors stuck on the surface of the components, and can only diagnose the faults of the components in the gearbox by testing the vibration signals at the bearing seat. Under this method, high-intensity operation can easily damage the vibration sensors, leading to poor signal-to-noise and distortion. In order to improve the quality of signal collection and diagnose main reducer faults in a timely manner, the research team has conducted research on acoustic signal based main reducer fault analysis technology and developed a set of acoustic signal based main reducer fault analysis technology.

This technology can achieve clear extraction and recognition of acoustic signal characteristics of typical faults in the main reducer under 5 typical fault modes (including gear erosion, gear tooth breakage, gear cracks, bearing cage fracture, shaft loosening, etc.), and construct a sound field imaging cloud atlas to achieve visual recognition of acoustic faults. It has the advantages of non-contact, nondestructive measurement, no need to modify equipment, and high monitoring efficiency. It has published 3 journal papers, applied for 2 invention patents to the China National Intellectual Property Administration, and obtained 4 software copyrights. It has mature technical capabilities, and is suitable for the application scenarios where it is inconvenient to modify or add sensors to installed helicopters, and maintenance personnel need to monitor on site at any time.

Assist in the rapid development of the transportation industry

This technology can be directly applied to the fault identification and early warning of key components such as helicopter gears, bearings, and shafts, which is of great significance for the safe use and efficiency of helicopters. At the same time, it can also ensure the quality of key components that undertake power steering and variable speed tasks in other products, such as transportation products such as cars, rail trains, and aviation that use gear and bearing components, and help promote the rapid development of the transportation industry.