Nondestructive evaluation of the structural damage based on the strain distribution information

A non-destructive evaluation technique based on full-field dynamic strain distribution information is presented in this paper. It is well known that the fatigue damage in advanced composites typically manifests itself in the form of a gradual reduction in local stiffness. The reduction of local stiffness will change the strain distribution at the corresponding area. By comparing the strain distribution over the surface of the structure, the fatigue damage in the structure can be detected and located. In the present study, a numerical simulation has been carried out to show that the fatigue damage in the structure can be detected and located by observing the changes in the strain distribution over the structural surface. The changes of the strain distribution are usually related to the damage pattern. It is found that when the damage is in the form of local stiffness reduction, strain distributions for all strain components will change in the same order of magnitude. When the damage is in the form of a crack, only the strain component which is perpendicular to the crack has a significant change. This suggests that it is possible to determine the damage pattern by examining strain distribution changes in all strain components.