Towards structural health monitoring of space vehicles

Abstract

Purpose The purpose of this paper is to report the results of a recent project of complex tests on the survival of structural health monitoring (SHM) technology with piezo wafer active sensors (PWAS) and electromechanical impedance spectroscopy (EMIS) at simulating the concomitant action of harsh conditions of outer space: extreme temperatures, radiations, vacuum. Design/methodology/approach The tests were conducted on PWAS, consists in adhesive and aluminium discs as structural specimens, with PWAS bonded on them. The substantiating of PWAS-EMIS-based SHM technique consists the fact that real part of the PWAS electromechanical impedance spectrum follows with fidelity the resonance behaviour of the structure vibrating under the PWAS excitation. This EMIS signature is very sensitive to any structural changes and, on this basis, can be monitored the onset and progress of structural damages such as fatigue, cracks, corrosion, etc. Findings The conclusion of the tests is that the cumulative impact of severe conditions of temperature, radiation and vacuum has not generated decommissioning of sensors or adhesive, which would have meant the compromise of the methodology. A second important outcome is linked to the capability of this methodology to distinguish between the damages of mechanical origin and the false ones, caused by environmental conditions, which are, basically, harmless. Originality/value The question of transfer of PWAS-EMIS-based SHM technology to space vehicles and applications received, as a novelty, a first and encouraging response.

New results concerning structural health monitoring technology qualification for transfer to space vehicles

“…At first sight, the conclusion is no longer valid in the case of the extreme temperature tests, see Table and Figure . However, by applying the compensation technique, the values in Table will be reduced to relatively small sizes that will not count in a potential online application using the method to identify the real damage. Indeed, the changes in the EMIS signature caused by extreme temperatures can be statistically summarized by two shifts: one horizontal and one vertical.…”

“…Toader, Ursu and Enciu show, among other things, a detailed online method for identifying damage based on neural networks, and Rugina, Enciu and Tudose focus on a detailed numerical and experimental study of EMIS signature changes due to structural damage and sensor degradation. Ursu, Toader and Enciu report the developments and the results of the first two years of the project, the main interest being focused on the description of the test protocols. Given that the project has enabled a very consistent database, Giurgiutiu, Tudose and Postolache propose an analytical approach for EMIS signature sensitivity in the presence of temperatures that simulate the conditions in outer space.…”

Assessment of Damage in Composite Pressure Vessels Using Guided Waves

“…This aspect is even more important for COPVs for space applications because structural component release is not feasible and the non-destructive evaluation should be undertaken during the mission. This is the main reason why SHM approaches have been recently introduced in the space field [ 13 ]. However, exploiting ultrasonic waves for condition monitoring is far from simple in such multilayered structures due to the complex propagation behavior.…”