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FEM modeling of guided wave behavior in integrally stiffened plate structures

Structural health monitoring (SHM) technologies, which use integrated sensing for damage detection, are expected to improve system reliability, availability, and operational cost. Guided waves can propagate great distances while experiencing low attenuation. They have been successfully used for damage detection in structures of relatively low geometric complexity such as plates and cylindrical pipes. The use of guided waves for this purpose becomes increasingly difficult as the geometric complexity of the structure increases. Aerospace structural components such as fuel tanks, wings, etc. often are comprised of substructures that consist of plates with integral stiffeners. This work reports on finite element simulations of guided waves in integrally stiffened plate structures. In these studies, the guided waves are generated by PZT wafer-type transducers mounted on the structure. Transient dynamic finite element simulations using PZFlex, in 2D and in 3D, were used to model both the structure and transducers. The interaction of the guided waves with cracks, simulated by notches of varying dimensions, is also modeled. This allows appraisal of the sensitivity of various modes for crack detection by providing insight into mode conversion and scattering resulting from the guided wave and crack interaction.