DEBOND DETECTION USING BROAD-BAND HIGH-FREQUENCY EXCITATION AND NONCONTACTING - LASER VIBROMETER SYSTEM

A membrane vibration-based method of detecting a debond between a host structure and a composite repair patch is presented. The two distingu ishing features of this new method are the excitation and the measurem ent. The excitation uses a non-instrusive surface-mounted piezoceramic patch and a broad-band high-frequency multi-sine sweep. The measureme nt uses a noncontacting laser vibrometer and converts the broad-band e xcitation response into a single value equal to the RMS value of the v elocity. The Frequency band is selected such that the local membrane v ibration of the debonded area is excited, resulting in relatively high er velocity in the debond area. The work is principally experimental w ith a theoretical justification of the membrane resonance detection te chnique, Two case studies of glass/epoxy repair patches bonded to alum inum plates with corner and edge debonds, respectively, are presented. In this work, it is shown that accurate detection of composite repair patch debonds is achievable.