Modal analysis is a technique for dynamic analysis of structures. Its objective is the estimation of dynamic properties such as natural frequencies, vibration modes and damping. Modal analysis can be theoretical or experimental. The theory is based on analytical and simulation techniques. The test is based on experiments and has four basic steps: excitation of the structure; measurement using accelerometers, digital processing and signal analysis and application of models.
This methodology is also used as a method for structural life monitoring (SHM). When a structure is damaged, the stiffness decreases and this affects their frequencies and natural vibration modes, i.e. it affects the way the structure vibrates. The change is detectable and comparable to an initial reference state of the undamaged structure. Furthermore, analysis techniques can detect the location and intensity of the damage, and, in the future, even forecast the behavior of the component or structure and the evolution of the damages.