Acoustic Emission-Based Structural Health Monitoring Framework for High Temperature Piping Systems

Wave-based Nondestructive Evaluation (NDE) of metallic piping systems in high-temperature environments faces challenges such as sensor temperature limitation, changes in wave characteristics due to temperature-induced material property, fluid-structure interactions, and geometric complexities including pipe elbows. The common form of damage that occurs in such critical piping systems is creep, which is the time-dependent deformation of metallic materials under sustained stress at high temperatures. Detecting and monitoring creep damage is essential for maintaining structural integrity. Acoustic Emission (AE) is an NDE method that detects propagating elastic waves released by active flaws in solids and enables real-time monitoring. This research provides a structural health monitoring (SHM) framework for monitoring and detecting creep damage in piping systems under high temperatures using AE, studied both numerically and experimentally through tests on metallic structures ranging from small dog-bone samples to a large-scale piping system. This research has four main outcomes: (1) Linear regression-based algorithm for detecting creep stage transition using AE data such as localized AE events, which can be adaptable to metallic materials under various experimental variables such as temperature and stress levels. It bridges the gap between traditional creep strain analysis and real-time damage monitoring. (2) Numerical models for simulating and visualizing wave propagation, analyzing geometric effects, and investigating multi-physics interactions coupled with piezoelectric sensor for real-world signal response simulation. (3) Implementing multi-task learning (MTL) for improving AE source localization accuracy in pipe structure with elbows. (4) Developing a regression-based location mapping approach based on AE system connectivity to enable source localization when the AE source is outside the sensor network in complex piping systems.