Experimental Vibration Testing and Nondestructive Testing

An overview of the Vibration and Experimental Modal Analysis (EMA) and system identification method and possible applications in non-destructive testing (NDT) is provided. The system identification in time, frequency and scale-time domain methods are presented. The illustrative examples of stiffness, mass and damping identification are provided. The theoretical and experimental basis of for mechanical system condition assessment is given. Displayed NDT method is based on the residual force vector and dynamic properties of the system. Theoretically, the method is applicable to any structure that can be accurately modeled using the finite element method and whose frequencies and mode shapes can be reliably obtained. To confirm the method numerically, it is applied to the numerical model of story frame, where the damage was simulated for three different cases: change in mass, change in stiffness and both change in mass and change in stiffness simultaneously. The practical, experimental, validity of the method is demonstrated by applying it to the free-free beam. It is shown that the practical application of the method requires additional actions, without which the method can be difficult to implement. This is a model update with which it is possible to achieve reliable modal parameters and the model reduction is used with which enables the equality of degrees of freedom between numerical and experimental model to be obtained