ESSPI non-destructive testing of honeycomb sandwich panel for bonding defects

Bonding defects of the honeycomb sandwich panel reduced its strength greatly, thus the application in aeronautics and astronavigation was influenced seriously. The basic principles of electronic speckle shearing pattern interferometry (ESSPI) were introduced. Using ESSPI technique and thermal loading method, non-destructive testing to honeycomb sandwich panels was conducted, then image processing was carried through compiled program. The validity and practicability of ESSPI technique was proved through the three-point bending experiment. The results show that the main reason of strength decrease is the defects of facesheet and honeycomb core debonding, and the ESSPI is very effective evaluation technique to the honeycomb sandwich panel quality.