Measuring delamination in carbon/epoxy composites using a shadow moiré laser based imaging technique

Delamination is considered one of the most serious problems associated with the machining of fiber-reinforced composite materials. The evaluation of the drilling-induced delamination damage in these materials is rather difficult, particularly for the carbon fiber-based composites. This is attributed to their color that makes the current visual inspection techniques extremely difficult. This paper presents a non-contact nondestructive technique for measuring and determining the extent of delamination in composite materials. The approach developed consists of utilizing a shadow moiré laser based imaging technique. This technique allows the assessment of the degree of delamination resulting from the machining processes necessary for final set-up and assembly. Mechanical drilling has been implemented on carbon fiber reinforced epoxy (CFRE) composites. The effects of cutting variables (feed and speed) on the delamination size in mechanical drilling of CFRE composites have been investigated. The discussed work should improve reliability and economy in fabrication and assembly of carbon fiber-based composites. Moreover, the results show that the proposed technique is easily adaptable to typical manufacturing environments and possesses promising advantages with respect to accuracy and simplicity.