TWI is involved in two broad monitoring fields. Structural Health Monitoring and Condition Monitoring. For ease of distinction and for TWI purposes, Structural Health Monitoring is concerned, as its name implies, with the structure, whilst Condition Monitoring deals with machinery, mainly moving components (gears, bearings and the like), but including boilers and heat exchangers.
Structural Health Monitoring (SHM) is the process of implementing a damage detection and characterization strategy for engineering structures. Damage is defined as changes to the material and/or geometric properties of a structural system which adversely affect its performance. The SHM process involves the observation of a system over time using periodically sampled response measurements from an array of sensors, the extraction of damage-sensitive features from these measurements, and the statistical analysis of these features to determine the current state of system health. For long term SHM, the output of this process is periodically updated information regarding the ability of the structure to perform its intended function in light of the inevitable aging and degradation resulting from operational environments. After extreme events, such as earthquakes or blast loading, SHM is used for rapid condition screening and aims to provide, in near real time, reliable information regarding the integrity of the structure.
The elements of an SHM system are:
- The structure
- Data acquisition system
- Data transfer and storage mechanism
- Data management
- Data interpretation and analysis