Ultrasonic repair of polymers : fundamentals and modeling for self-healing

Abstract

Although current research focuses within self-healing materials are advancing, most pursuits are passive systems, unlike the active biological systems they aim to mimic. In this paper an active method utilizing ultrasonic energy is explored. Ultrasonic inspection has served as an effective means toward nondestructive damage detection for decades. Also, a recent method called time-reversed acoustics allows for the redirection of acoustic waves back towards the source. The active healing method utilizes ultrasonic nondestructive damage detection to locate and categorize damage, and then provide coordinates for the redirection of an amplified ultrasonic energy to heal the material. First, the temperature change as a result of ultrasonic treatment was measured, and then a variety of dogbone samples were tensile tested, including virgin samples, damaged samples, and damaged but ultrasonically treated dogbone samples. The ultrasonic treatment increased the ultimate stress of the ultrasonically treated dogbone samples, which was a result of increased crystallinity. The crystallinity was confirmed with differential thermal analyses. The ultrasonic influence of material temperature and effect of ultrasonically treated damaged samples versus just untreated damaged samples were replicated with finite element models as a means to predict future application and use.