Structural Health Monitoring
The main purpose of Structural Health Monitoring (SHM) is the diagnosis of the life cycle of an object, the material states, its components, various parts of the structure, as well as the whole object at each moment. For normal operation of the object, the parameters characterizing its condition must remain within the permissible ranges defined at the development stages. The main factors affecting the structure state are wear during operation, the impact of negative external factors (temperature, humidity, etc.), as well as some force majeure events (earthquakes, floods, volcanic eruptions, etc.). The continuity in time of the SHM process allows one to accumulate information about changes in the object state and then, using various mathematical models, to predict the accumulation and development of damage and the residual life.
If we consider only the diagnostic function, then SHM can be considered a new improved approach in traditional non-destructive testing (NDT).
However, the SHM concept is broader than the classical NDT, since it involves the integration of sensors system, data acquisition and transmission units and computing power for their processing directly into the operated structure. The SHM implementation involves a review of the processes of designing structural elements, a change in the organization of the operation process, both of individual structural elements, and of the whole object.
The figure below shows a diagram of a typical SHM system. The first part of this system responsible for monitoring the physical integrity of the structure, is determined, firstly, by the physical phenomena type (correlated with the damage type that must be detected) monitored by sensors and, secondly, the type of physical phenomenon used by the sensor to generate the scan signal sent to the subsystem of collection and storage of information.Several sensors of the same type form a network; the information obtained with its help is combined with the data of sensor networks of other types. With the use of sensors that measure environmental conditions, it becomes possible to implement the function of monitoring the operation processes. The signals generated by the integrity monitoring system, in parallel with previously measured data, are used to diagnose the structure state. By combining information from the integrity monitoring subsystems with the data of the operation monitoring subsystem, as well as with the knowledge base on the mechanisms of formation and development of various types of damage, it is possible to make a forecast about the remaining life of the structure and implement the “health monitoring” of the object (determine the maintenance procedure, organize repair work, etc.).
The main positive effects of the introduction of SHM systems are as follows:
a) The main positive effects of the introduction of SHM systems are as follows:
b) enhanced capabilities in the construction of new objects;
c) radical change in the organization of the works of maintenance and repair services consisting in replacement of periodic service at equal intervals of time for service on the current technical condition or, at least, in reduction of expenses for dismantle and check of those parts of a design in which according to system SHM defects are absent. In addition, the human factor impact (labor costs, possible errors of personnel, etc.) is significantly reduced, which should contribute to improving the reliability of maintenance.
The research of IMMI team in the Structures Health Monitoring field are focused on the development of mathematical and computer models of physical phenomena and processes.
