Book Description

Neutron radiography was found to be effective as a nondestructive inspection technique for detection of bondline voids/defects in a variety of composite structures. Radiographic data are presented in this paper from typical structures for which the neutron radiographic inspection technique offers advantages over more convetional inspection techniques. Complex composite joints such as box beam members, for example, are difficult to inspect by ultrasonic techniques, and the X-ray attenuation coefficients of the different materials in composite/metal combinations differ in such a manner as to yield very little nondestructive inspection (NDI) information regarding the integrity of the bond. Accurate bondline defect information was achieved in such structures utilizing a transportable californium-252(252Cf) neutron radiography system containing approximately 2 mg of the 252Cf isotope. Through techniques developed at Vought Corp. Advanced Technology Center, resolution of simulated bondline voids as small as 0.127 mm (0.005 in.) diameter in laminated graphite/epoxy specimens was achieved. It is expected that continuing improvements in imaging techniques, and in mobility of neutron sources for radiography, will spawn wide usage of the neutron technique for nondestructive inspection of complex wing joints, control surfaces, and other airframe structures.