Proof of concept for impact and flaw detection in airborne structures

Abstract

All structures are subject to unwanted and uncontrolled bumps. For instance, when considering airborne vehicles, birds, hail, and meteors are usual sources of collision. Depending on the location and energy of the impacts, they can weaken the structure critically. On the other hand, ageing, scratching, corrosion, and manufacturing flaws also weaken structures. Furthermore, the subsequent damage could not be visible, as it usually happens in composite material made structures. This paper focuses on the detection of impacts and flaws of structures in airborne vehicles with an electronic prototype developed specifically for SHM (Structural Health Monitoring). Two types of tests were performed, the ones to detect impacts, and those to detect flaws. Both are based on the propagation of ultrasound acoustic waves. The setup of the tests includes the structure under test, a set of transducers, a structural health monitoring ultrasound system (SHMUS), and the software to control the monitoring tool. The first type of tests are based on the Impact Detection System (IDS) included in SHMUS. Any impact on the structure under test generates an acoustic wave that IDS detects. The parameters of the waveform generated depend on the energy that the impact provides. The second type of tests, the flaw detection tests, are performed with SHMUS, which generates and acquires electric signals, and simplify them for further analysis and health diagnosis of the structure. Once an impact is detected, it is critical to know the degree of damage caused to the structure. To this end, SHMUS can perform an SHM test, the second type one. The results show that the monitoring system SHMUS satisfactorily detects impacts and flaws as well as measures the damage as a decrease of the health of the structure under test. Furthermore, the decrease detected is proportional to the severity of the damage.