Ultrasonic data transmission across metal structures affected by environmental conditions

Abstract

Variable environmental conditions present a major hurdle for Structural Health Monitoring (SHM) systems which involve the signal processing of Ultrasonic Guided Waves (UGW). Two important cases of variable conditions are investigated in this article: (i) The effect of changing temperature and (ii) the impact of water surrounding a technical structure. In two complementary case studies, an aluminum plate and a steel pipe with flange are examined. The article concentrates on the emerging task of UGW-based data transmission across these solid waveguides. In particular, permanently attached piezoelectric transceivers are deployed for digital communication using amplitude modulation, namely on-off keying (OOK). The laboratory experiments are accompanied by a mathematical treatment as well as numerical simulations. Successful data transmission is established and analyzed. Based on the provided analysis, distinct strategies are identified for reliable communication in the presence of changing environmental conditions. The results are of eminent importance in the framework of SHM where, apart from monitoring, the supplementary capability of the transceivers to exchange health-related information across the waveguide itself, represents an innovative feature for the design of future intelligent SHM systems.