1,720,967 research outputs found
Optical fiber sensor fusion for aerospace systems lifecycle management
Get PDFOptical fiber is a material that can transport light signals, so resulting useful for data transmission and sensing applications. Fiber Bragg Gratings (FBG) are a specific type of optical sensors that can measure parameters like temperature, strain, and vibration. The PhD program focuses on developing a sensing and monitoring strategy for aerospace systems using FBG sensors networks. The study will include material selection, optical fiber manufacturing, sensors packaging and integration, calibration and interrogation techniques and smart logics development for acquiring and controlling phenomena affecting the equipment under test. Some experimental activities have already been conducted to analyse thermal and mechanical sensing and to define a reliable methodology for integrating sensors into various systems. During the tests, FBGs were found to have high accuracy and sensitivity for thermal variations, mechanical strain and shortterm thermal transients. The crucial role of bounding technique was also enhanced. Additionally, more complex tests have been conducted for sensor more realistic systems, both for space and aeronautic environments. The results gained in this first period are positive and encouraging, suggesting further developments during PhD progra
Innovative sensor networks for massive distributed thermal measurements in space applications under different environmental testing conditions
Get PDFOptical fiber has seen significant development in the technical fields where it has been used in the last years. In the first place, obviously, for the Internet and, more broadly, to improve communication efficiency; but, more recently, for medicinal, structural, or lighting engineering applications. Furthermore, many optical solutions are beginning to be researched in the aerospace sector. The use of optical fiber, in particular, is strongly related to the employment of FBG type optical sensors, which may be particularly suitable for specific measurements of relevant physical parameters to be performed on specimens with typical aeronautical and/ or space employment. More specifically, the performance of several FBG sensors for temperature measurement in vacuum for validation tests of space products has been examined during this work. Unlike typical thermocouples, the adoption of this new type of sensor can provide substantial benefits, beginning with a significant gain in terms of the size of the fiber, which ensures a minimum disturbance on thermal data. Furthermore, if supplied with a suitable coating (in polyimide), the optical fiber may guarantee a very high operating temperature range, which is extensively compatible with the high-temperature range existent in space. The measurements were divided into two independent phases. First, a preliminary test was performed in the laboratory using a climatic chamber to evaluate several sensor network integration methodologies on the specimens and select the most effective one for the vacuum test. The test demonstrated that a simple adhesive bonding of the fiber to the specimens ensures a precise temperature measurement under vacuum and stable conditions. The following vacuum test program confirmed that FBGs could be used as temperature sensors even at very high temperatures. The good results of this test encourage us to consider FBG strategic for space applications and, particularly, for thermal characterizations, thanks to the high number of available sensors, combined with the minimal cable's size. However, further studies are required in cryogenic cases to validate the entire range of extreme temperatures that characterize the space environment
Thermomechanical calibration of FBG sensors for aerospace applications
Get PDFOptical fibers have found widespread use in engineering, from communication to sensors. Among them, Fiber Bragg Gratings are allowed to detect several parameters. Scope of this work is to assess their performances as temperature and mechanical strain sensors for aerospace: in this regard, an experimental calibration is discussed. Then, alternative approaches are tested in order to distinguish thermal from mechanical contributes. This is first addressed by using a hybrid system of digital and optical sensors, and then then with a fully optical system. Both the presented solutions reached the scope. A concept of a third, innovative approach, is also described
PROGNOSTICS OF AEROSPACE ELECTROMECHANICAL ACTUATORS USING THE FAILURE MAPS TECHNIQUE
Get PDFThe gradual deployment of Electro Mechanical Actuators (EMAs) as primary flight controls actuators, driven by the “more electric” approach, must be paired up with a solid prognostic background in order to overcome the limited experience and to support the system during his lifecycle. In fact, assessing EMAs actual states thanks to Prognostic and Health Monitoring (PHM) systems and detecting potential failures is crucial to guarantee the compliance to the relative safety requirements. The research activity described in this paper focuses on the development of a model-driven deterministic methodology based on Failure Modes Maps (FMMs). Thanks to data obtained through a Numerical Test Bench (NTB) and a Simplified Model (SM), the proposed prognostic algorithm is proved capable of detecting and identifying the source and magnitude of two different failures: rotor eccentricity and increased friction. After a short description of the implemented models and a general overview of typical EMA failure modes as well as FMMs development, the proposed algorithm is explained in detail. This is followed by a comprehensive study of the two simulated failures as well as the creation of the relative FMMs. Finally, the proposed prognostic algorithm is successfully applied on the obtained FMMs
A genetic-based prognostic method for aerospace electromechanical actuators
Get PDFPrior awareness of impending failures of primary flight command electromechanical actuators (EMAs) utilizing prognostic algorithms can be extremely useful. Indeed, early detection of the degradation pattern might signal the need to replace the servomechanism before the failure manifests itself. Furthermore, such algorithms frequently use a model-based approach based on a direct comparison of the real (High Fidelity) and monitor (Low Fidelity) systems to discover fault characteristics via optimization methods. The monitor model enables the gathering of accurate and exact data while requiring a minimal amount of processing. This work describes a novel simplified monitor model that accurately reproduces the dynamic response of a typical aerospace EMA. The task of fault detection and identification is carried out by comparing the output signal of the reference system (the high fidelity model) with that acquired from the monitor model. The Genetic Algorithm is then used to optimize the matching between the two signals by iteratively modifying the fault parameters, getting the global minimum of a quadratic error function. Once this is found, the optimization parameters are connected with the assumed progressive failures to assess the system's health. The high-fidelity reference model examined in this study is previously conceptualized, developed, implemented in MATLAB-Simulink and finally experimentally confirmed
Analysis of FBG Sensors Performances When Integrated Using Different Methods for Health and Structural Monitoring in Aerospace Applications
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Experimental development and evaluation of a fiber bragg grating-based outside air temperature sensor for aircraft applications
No full textThis study presents the development and rigorous evaluation of a Fiber Bragg Grating (FBG)-based Outside Air Temperature (OAT) sensor designed for aircraft applications. Employing a Design of Experiments (DoE) approach, the research optimized the sensor's performance for reliability, accuracy, and durability in aviation environments. Experimental assessment covered detailed installation of the FBG sensor on an aircraft, considering influential parameters such as outside dimensions and varying temperature. The OAT sensor's design focused on robustness and precision for accurate real-time temperature recording, vital for operational efficiency and safety. Extensive statistical analysis assessed the sensor's performance under differing conditions, providing valuable insights into operational capabilities and overall efficacy. Thermo-climatic chamber tests simulated extreme environmental conditions to validate the sensor's durability and function under potential aircraft operational scenarios. This research enhances understanding of FBG-based OAT sensors for aircraft applications, demonstrating their superior robustness and performance capabilities, thereby contributing to aviation safety, operational efficiency, and data precision
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Smart Composites Manufacturing and Testing by Insertion of Fiber Bragg Gratings Sensors
No full textThe development of aerospace systems requires to consider the complex challenge of having a wide network of sensors capable of ensuring high performance even in hostile environments. Fiber Bragg Grating (FBG) optical sensors effectively meet this goal, providing immunity to electromagnetic interference, minimal invasiveness, sensitivity to various physical parameters and a high operating temperature range. In particular, the minimal cable size of optical fiber lets the integration of optical sensing directly during the part manufacturing phase. This innovative approach could ensure the development of smart components, capable of autonomously providing fundamental data for the development of control algorithms, diagnostics, and predictive maintenance. This article describes the procedure for the fabrication and thermal testing of a composite material specimen, where the FBG was directly positioned during the lamination phase. Once successfully prepared, the specimen was tested in a climatic chamber through repeated thermal cycles. The measurements proved excellent thermal sensitivity, with a well-linear calibration curve unaffected by the lamination process. Moreover, the experimental campaign allowed for the calculation of the thermal flux trend within the specimen through-out the thermal cycle. The study, therefore, enhanced the huge potential of this method, from real-time monitoring to be data source for Artificial Intelligence or Augmented Reality
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