PSI - Issue 54

Vasiliki Panagiotopoulou et al. / Procedia Structural Integrity 54 (2024) 482–489 Vasiliki Panagiotopoulou/ Structural Integrity Procedia 00 (2023) 000 – 000

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1. Heritage of SAMAS 2 Several projects, including HECTOR (2009-2011), ASTYANAX (2012-2015), and SAMAS (2017-2020), have contributed to the development of Structural Health Monitoring (SHM) methodologies for monitoring damage in aircraft structures. The latest project in this series, SAMAS 2, aims to advance the technology's readiness level (TRL) to 6-7 by applying it to a real military helicopter. This involves conducting laboratory and flight tests to assess damage from both corrosion and ballistic impact. The project focuses on AW139/189 helicopters of Leonardo Helicopter Division (LHD) and a Mil Mi17 Polish helicopter, with specific attention to the tail rotor shaft and certain structural components. SAMAS 2 is considered a challenging project, as it involves the implementation of cutting edge algorithms, models, and sensing technologies based on accelerometers. 2. General introduction The primary objective of this project is to employ state-of-the-art modeling techniques for the analysis of signals acquired by sensors, with the aim of developing a robust and comprehensive method for identifying, monitoring, and predicting potential damage in the tail transmission line of a helicopter. Specifically, military helicopters are exposed to various types of damage and degradation as a result of their operational conditions and mission scenarios. In particular, the helicopter's tail rotor drive line (TRDL) serves as the sole transmission pathway for the engine to transfer power to the tail rotor, without any redundant backup. On top of that, due to its length and inherent vulnerability, the TRDL is the system most susceptible to damage, which could potentially compromise the entire structural integrity and the safety of the crew. At the same time, corrosion damages can significantly affect the structural integrity of the helicopter if inspections and maintenance activities are not conducted at frequent intervals. So far, the structural safety of helicopters is ensured based on a series of analyses during the design phase and a strict schedule of inspections during life. Only few attempts have been carried out to directly monitor the structure in operation by implementing robust and reliable methods. The motivation for suggesting Structural Health and Ballistic Impact Monitoring and Prognosis lies in its potential to enhance helicopter and crew safety by mitigating accidents before they occur and increasing helicopter availability through improved maintenance planning.

The purpose of SAMAS 2 is the development of a corrosion SHMP system for evaluating the corrosion level of the different structural elements and estimate the residual life before their substitution is required. Additionally, the creation of an advanced tool for ballistic impact, load, and damage monitoring is an integral part of the defined SHMP. This system is entitled to identify the occurrence of a ballistic impact, localize it, and estimate the damage progression under the measured load spectrum. One main goal is the development of a Digital-Twin and a Health & Usage Monitoring System (HUMS) able to extract relevant damage features from sensors’ signal and to provide both the actual healthy condition of the structure and prognosis life estimation. The Digital-Twin is based either on Fig. 1 Framework of SAMAS 2 project