One dimensional modeling of ultrasonic characterization of face sheet coredebonding in composite sandwich panels

Theoretical models of ultrasonic wave propagation in polymeric composite sa ndwich panels, deteriorated by various types of face sheet core debonding, are analyzed. All sandwich panels consist of a core of one material and two identical face sheets of a second material. Debonding, either completely o r partially, is modeled at either of the face sheet core interfaces. For th e constant amplitude input and the corresponding steady state output (both of which are observed at the top surface), all models produce similar outpu t spectra, though each model displays distinctive characteristics. The unda maged sandwich panel can be distinguished from any of the debonded panels b y the presence of detectable waves along the unloaded bottom surface, espec ially at frequencies near the through thickness natural frequencies of the top or bottom face sheet in the corresponding longitudinal or shear wave mo de. Distinguishing the top face sheet core debonding or the bottom face she et core debonding, however, requires detecting narrow secondary peaks in th e output spectra, which imposes more challenging demands on experimental me asurements.