Improving Wavelet Transform for the Impact-Echo Method of Non Destructive Testing

摘要

The impact echo method, a technique based on the use of transient stress waves, has been used successfully for detecting flaws in many different types of concrete structures, including plate-like structures such as bridge decks, slabs, walls, beams, columns, layered structures and hollow cylindrical structures. Usually the received signals consist of components and additive structural noise. This noise often masks the signal of the defects and creates an embarrassment in its detection. Also, in thin samples the reflected signals are overlapping thus making detection of defects in the sample and accurate measurements impossible. It is thus necessary to enhance the visibility and resolution of the defects echoes by signal processing techniques for characterizing, detecting and locating the imperfections present in the used materials.