Active SHM for composite pipes using piezoelectric sensors

Abstract

Composite materials, in addition to the high specific mechanical properties, have properties enabling their applications in high-pressure, high-temperature (HPHT) and corrosive environment as occurs in deep water. Their use for manufacturing pipelines and offshore risers can provide relevant performance advantages over steel such as lower weight, improved fatigue capacity, corrosion resistance and higher strain limits. However, composite materials are more complex to use in design than metallic materials due to their anisotropic properties and lack of accurate failure prediction models. Thus, a continuous in-situ and in real-time Structural Health Monitoring (SHM) of composite components would be necessary and useful to promote their use in a wider range of operational conditions. In this work, an FRP pipe sample was instrumented with Piezoelectric Wafer Active Sensors (PWAS) used either as passive receivers or as transmitters of guided waves for active health monitoring in pitch-catch configuration. The propagation properties of guided waves in glass fibres reinforced composites were studied by developing MATLAB scripts, running FE simulation and experiments. The numerical and experimental signals were post-processed in MATLAB by Short Time Fourier Transform (STFT) in order to evaluate their frequency and time-frequency content. Furthermore, the guided waves were used to detect artificial defects imposed on the structure identifying their location. Several testcases were studied to find out the limitations and the most suitable conditions of using guided waves for defects monitoring in a composite pipe. The work proposes effective methods for pipe structural health evaluation by non-destructive techniques and ultrasonic guided waves.