Load monitoring is a key component of structural health monitoring. In fact, knowing the value of the loads acting on a structure, it is possible, using a numerical model, to reconstruct values of strain, stress and displacement in all the structures. In this work, inspired by an international research project called “SAMAS” and from the work of thesis “Design and implementation of a load monitoring system for aeronautical structures based on a calibration matrix approach”, load monitoring is applied practically to two structures. The first is a stabilizer of a military Unmanned Air Vehicle. On the specimen are installed strain sensors, and through two hydraulic actuators can provide the required forces. Effectiveness of load monitoring is tested using data collected during an on-ground experimental program. In this way, different sensors and acquisition systems, including strain sensors based on fiber optics technology like Fiber Bragg Gathering (FBG) and Rayleigh backscattering sensor (RBS), temperature sensors, and load cells, can be applied on the specimen neglecting weight issues. Moreover, temperature changes are slower, there is no effect of direct sun or wind pressure, and the forces are well known. The second structure, referred to as “Hornet”, is a complete Unmanned Air Vehicle. Strain measures acquired during flight test are analyzed to determine the effectiveness of the load monitoring system based on the calibration matrix approach. Forces acting on the structure due to aerodynamics are unknown. Thus, the effectiveness of the reconstruction is based on the comparison between measured and reconstructed strain, compensating thermal effects.
Il monitoraggio dei carichi è una delle componenti fondamentali per il concetto di monitoraggio strutturale. Infatti, conoscendo il valore dei carichi agenti su una struttura, è possibile, tramite un modello numerico, ricostruire i valori di sforzi, deformazioni e spostamenti. In questo lavoro, che prende spunto da un progetto di ricerca internazionale denominato “SAMAS”, e dal lavoro di tesi “Design and implementation of a load monitoring system for aeronautical structures based on a calibration matrix approach” il concetto di monitoraggio carichi è applicato in termini pratici a due strutture. La prima è uno stabilizzatore di coda di un drone militare. Su questo provino sono applicati dei sensori di deformazione in fibra ottica, basati sulla tecnologia Fiber Bragg Gathering (FBG) e Rayleigh backscattering sensor (RBS), sensori di temperatura e celle di carico. Tramite due attuatori si andrà a sollecitare la struttura. Dopo la campagna sperimentale, si andrà a verificare l’efficacia della ricostruzione tramite matrici di calibrazione numeriche, ottenute da simulazioni, e sperimentali, ottenute dalle misure effettuate. Il vantaggio di avere questa struttura a terra è il fatto di poterci collegare tutti i dispositivi di acquisizione senza preoccupazioni per il peso. Inoltre, essendo al chiuso, i cambi di temperatura avvengono lentamente, e non c’è effetto del deretto irraggiamento solare, della pressione del vento, e le forze appicate sono misurabili. La seconda struttura è un Unmanned Air Vehicle (UAV), un drone militare completo soprannominato “Hornet”. Di questo, si andranno ad analizzare le misure acquisite durante i test di volo. Le difficoltà, in questo caso, sono date dal fatto che i carichi dovuti al campo aerodinamico non si possono ne controllare direttamente, ne misurare. Perciò, l’efficacia della ricostruzione si baserà solo sul confronto tra deformazioni misurate e ricostruite, compensando gli effetti termici.
Implementation of load monitoring based on a calibration matrix approach on aerospace composite structures
NARDI, ETTORE
2018/2019
Abstract
Load monitoring is a key component of structural health monitoring. In fact, knowing the value of the loads acting on a structure, it is possible, using a numerical model, to reconstruct values of strain, stress and displacement in all the structures. In this work, inspired by an international research project called “SAMAS” and from the work of thesis “Design and implementation of a load monitoring system for aeronautical structures based on a calibration matrix approach”, load monitoring is applied practically to two structures. The first is a stabilizer of a military Unmanned Air Vehicle. On the specimen are installed strain sensors, and through two hydraulic actuators can provide the required forces. Effectiveness of load monitoring is tested using data collected during an on-ground experimental program. In this way, different sensors and acquisition systems, including strain sensors based on fiber optics technology like Fiber Bragg Gathering (FBG) and Rayleigh backscattering sensor (RBS), temperature sensors, and load cells, can be applied on the specimen neglecting weight issues. Moreover, temperature changes are slower, there is no effect of direct sun or wind pressure, and the forces are well known. The second structure, referred to as “Hornet”, is a complete Unmanned Air Vehicle. Strain measures acquired during flight test are analyzed to determine the effectiveness of the load monitoring system based on the calibration matrix approach. Forces acting on the structure due to aerodynamics are unknown. Thus, the effectiveness of the reconstruction is based on the comparison between measured and reconstructed strain, compensating thermal effects.File | Dimensione | Formato | |
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https://hdl.handle.net/10589/165133