Damage location systems based on electromechanical impedance and baseline-free guided waves under low signal-to-noise ratio conditions

Abstract

Nowadays, the development of monitoring systems capable of providing a reliable diagnosis of the integrity of civil, mechanical, naval and aerospace infrastructure is a critical concern in the society and a challenge for the research community. The advent of the intelligent materials, modern techniques of the digital signal processing have improved effectiveness of the Structural Health Monitoring (SHM) engineering field. The current challenge is to refine the capabilities of this type of engineering systems in order to ride out the gaps of real world, where several physical variables, such as the environmental noise, can harm the effectiveness of these methodologies. On the other hand, current advances and challenges are also focused on intelligent and independent SHM systems. The new objection and trend are to develop baseline-free systems because, in many situations, the past structure condition is not available or was already accomplished in a structural damaged condition. Based on this facts, providing a methodology which allows a deeper knowledge of electro-mechanical impedance (EMI) technique, the currently PhD Brazil scholarship sponsored by FAPESP (grant #2015/24903-5), is focused on expand this promising SHM technique in the real applications, where the structure noise harms the correct failures diagnosis. Although the efforts of currently research achieving in Brazil are concentered in the actual SHM industry and academic challenges, the project is focused on damage detection, not on damage localization. On the other hand, EMI relies a pre-stored knowledge of the structural condition to perform the damage detection, and, therefore, it is not a type of independent system due the need of extraction of a baseline impedance signature of impedance extraction. Instead of EMI, baseline-free guided waves (BFGW) is an independent system which aims the damage location by a set of pitch-catch piezoelectric sensors that emit Lamb waves on structure. A reconstruction algorithm for the probabilistic inspection of damage accomplishes the location, by applying the time reversal approach for each set of piezoelectric transducers attached on a host structure. Although many studies also proved the effectiveness of this baseline-free damage location system, one of the most problems can be the variations of the acoustic emission signals due the external noises, which is common to occur in the real applications. Based on these issues, this BEPE project aims to improve the currently PhD Brazil project, by developing of a damage localization EMI-based in noisy inspections and also compare and improve the performance of baseline-free guided waves approach under low signal-to-noise ratio (SNR) conditions. Therefore, this BEPE project aims to improve and extend these structural monitoring approaches in a low signal-to-noise ratio (SNR) applications once the actually goal and challenge of the SHM field is to develop system capabilities to respond correctly to gaps in the structure's knowledge and environmental changes. The student will be under the supervision of Professor Francesco Ciampa, whom is actually a second supervisor of Mr. Bruno and has already established guidelines for methodological development that allow a deep knowledge of baseline-free and damage location methodology. This project will depend on resources available on the Centre for Engineering Materials (CEM), University of Surrey, Guilford, United Kingdom, institution where have a partnership signed with FAPESP. Research activities at CEM are also synergetic to the Surrey Space Centre, a world leading centre of excellence in space engineering. Thus, the proposed research will have an important contribution in the improvement of the damage location systems based on EMI and baseline-free guided waves, especially in applications with low SNR.