Neutron imaging as a tool for the non-destructive evaluation of adhesive joints in aluminium

Quantitative evaluation of imperfections in adhesive joints remains one of the most challenging problems prior to industrial implementation of nondestructive testing. This paper reviews the defects that are a concern in adhesively bonded joints and how these were simulated with artificial imperfections. Investigations involving neutron radiography on aluminium-epoxy bonds, performed at the NEUTRA radiography station in Paul Scherrer Institute, Switzerland, demonstrate the applicability of the method. The detectability of defined imperfections is shown through experimental observations of the transmission images. A subsequent evaluation of the defect bond area with image analysis enables a correlation to strength.