Delamination Detection - A Vibration-Based Approach

In this chapter the damage detection studies in composite materials were summarized in the context of structural health monitoring, which is referred as the process of implementing a damage detection strategy for mechanical engineering infrastructure (Allix and Blanchard 2006). The review of the theoretical aspects related to the detection of damages induced by delamination in composites was oriented in two main directions: - the nondestructive evaluation method using an ultrasonic technique with Lamb waves, which is an experimental method able to provide local damage information - the model dependent method, undertaken analysis of structural models implemented by finite element analysis and able to provide global damage information, for linear and non-linear mechanical behavior of the system The structural health monitoring process of big wood laminated structures, in light of normal aging and degradation resulting from operational environments, must involve the periodic inspection of the system using: - sampled dynamic response measurements from an array of transducers, establishing their number, resolution, bandwidth, data acquisition (periodically or continuously), storage and transmittal hardware; - extraction of the damage - sensitive features, normalization of data by the measured inputs or by environmental cycles (summer, winter); - statistical analysis of data to determine the current state of the system.