Method of proving the quality of a bond

METHOD OF PROVING THE QUALITY OF A BOND A method of assessing bond quality of a bond between first and second composite parts (102, 104) may include bonding an indication film (126) to the first composite part (102). The indication film (126) may include NDI-detectable particles (132) arranged in a pattern (142) and bound to polymer chains (148) located inside particle regions (134). The polymer chains (148) and particles (132) may be stationary during bonding of the indication film (126) to the first composite part (102). The method may additionally include bonding the first and second composite parts (102, 104) along an assembly bondline (116) during which the particles (132) in the indication film (126) migrate with the polymer chains (148). The method may further include NDI-inspection of the assembly bondline (116) by observing the appearance of the particles (132) along a direction locally normal to an in-plane direction (110) of the assembly bondline (116), and determining the bond quality of the assembly bondline (116) based on particle density in the in-plane direction (110). (DD *4444444 CV4444444+ (D4444444 4944444944*44 04 9444*444 0 0 0444444