Damage Detection in Composite Structures Using Time-Reversal Migration Technique

The use of composites in aircraft manufacturing is growing dramatically. Ultrasonic guided waves (UGW) can propagate a long distance, and thus have been used in structural health monitoring (SHM) for large area composite structures like wings and fuselages. In this paper, a movable linear-array transducer along with time-reversal migration (TRM) technique has been adopted as a nondestructive inspection (NDI) tool to rapidly inspect and reconstruct the image of damage in composites. With this linear-array transducer, each time one element is used as the actuator and the rest of elements are used as receivers. Subsequently, a TRM image of damage (or the secondary sources) in the composite specimen is reconstructed through TRM technique. By sequentially switching the element in the linear-array transducer as the actuator, a set of TRM images of the same damage in the composite are reconstructed. Through stacking all images together, a final image of the damage with higher accuracy and lower noise rather than each individual image can be obtained. Experiment results confirm that the linear-array transducer and TRM technique can be a promising NDI tool for rapid inspection of damage in composite structures.