Structural Health Monitoring and Damage Identification
An updated finite element model reflects the observed dynamic characteristics of the real damaged structure. When this model is compared against a reference model of the undamaged structure, structural changes can be detected, serving as a monitoring, damage detection or QA method. The major tasks in structural health monitoring and damage identification are
identifying the existence of damage (correlation analysis)
identifying the location of the damage (error localization, sensitivity analysis)
estimating the magnitude of the damage (model updating)
estimating the residual lifetime of the structure
When damage is completely identified, it can be decided to repair the structure or replace it. In practice, damage detection relies not only on error localization methods but also on correlation analysis, sensitivity analysis, model updating, numerical experimentation, simulation of damage patterns etc. This is still an area of extensive research and new methods and procedures are proposed regularly. It is also clear that successful damage detection largely depends on the amount and quality of the test data.
Applications can be found in all kind of industries but particularly in:
- Civil infrastructures: Bridges, highway systems, buildings, power plants, etc.
- Aircraft and missile structures: Helicopters, airplanes, engines, motor cases, etc.
- Space structures: Satellites, space stations, reusable launch vehicles, etc.
- Land/Marine structures: Automobiles, trains, submarines, ships, etc.
- Machinery: rotation machinery, robots, etc.
Structural Health Monitoring and Evaluation
Test data can be acquired continuously or at specific time intervals during the lifetime of a structure and combined with damage detection routines. These techniques have become popular in recent years thanks to the availability of new test postprocessing methods like operational modal analysis (OMA).
Operational modal analysis is a method to analyze structural vibrations without knowing the input force. New methods are available to identify resonances and mode shapes directly from time histories. Combining finite element analysis with OMA can be used as a powerful damage identification tools that can run in an automated way. This technique is used for bridges, dams, aircraft and other structures and machinery in order to avoid structural damage and failure. A typical application is the post-earthquake structural condition assessment by real-time vibration monitoring.
This is an application of damage detection where the detection procedure is applied on large quantities of identical products. Like structural monitoring, the focus is on identifying the existence of damage. Localization and quantification of damage will be done only if repair costs are low compared to manufacturing costs.
Residual Lifetime Estimation
Combining structural health monitoring with fatigue analysis allows to estimate the residual lifetime of structure under dynamic loading.