Detection of unbonds in honeycomb sandwich using MIA

Hi,

I would like to clarify for the detection of unbonds in honeycomb sandwich using MIA

1. For the stiffness differences that the MIA method is detecting, is there any contribution to this stiffness difference from the composite face-sheet on the opposite side or is it mainly due to the honeycomb core that the face-sheet is bonded to?

I.e. we are comparing stiffness of near-side face-sheet only (for unbond) versus

Case 1: honeycomb core + near-side face-sheet only (good area)
Case 2: honeycomb core + near-side face-sheet + far-side face-sheet (good area)

Assume CFRP face-sheet of 2-3 plies so around 0.5mm thick and Nomex Honeycomb of about 5mm thick.

2. What is the effect of the probe diameter on the detection performance?

Thanks for the help!!