Monitoring the evolution of the stiffness during the ultraviolet cure with air-coupled ultrasonics

Abstract

The ultraviolet (UV) curing process is gaining interest due to the curing speed, since it increases the production of the manufacturing processes. The high mechanical requirements of composite materials require the assurance of quality from the mechanical point of view. The inspection after processing is an additional operation that increases the costs and production times, so the monitoring of the mechanical properties, more specifically the evolution of the rigidity during the curing process, is strategic for the greater penetration of the composite materials in sectors dominated by the final price of the piece. Monitoring the elastic properties during curing, when contact between the piece and the sensor is not possible, is a challenge for rapid processes such as UV curing. The present work demonstrates the validity of the ultrasonic monitoring technique with air coupling (ACUS) for different UV curing conditions. Three conditions of UV curing (0.8, 1.6 and 2.4 W / cm2) were studied on a vinyl ester resin. The results of the ACUS are consistent with those of the direct current sensor with contact. The main conclusion is that the evolution of the rigidity with respect to the degree of conversion is similar for the different conditions studied.

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