Numerical study of the heating effects of high intensity focused ultrasound on shape memory polymer fiber reinforced self-healing polymer composite

In polymer composites, constrained shape recovery, either by shape memory polymer (SMP) matrix or embedded SMP fibers, is utilized to close wide-opened cracks, followed by molecular scale healing either extrinsically or intrinsically, the so-called close-then-heal strategy. The most popular means to trigger shape recovery and healing is by heating. In this study, the potential for using high intensity focused ultrasound as a trigger for shape memory effect and self-healing of an SMP fiber-reinforced thermosetting polymer composite was explored. The objectives of the study were achieved via a finite element simulation in COMSOL Multiphysics. Simulation results showed that for an 8 mm thick, 18 mm long model composite with 5.8% SMP fiber volume fraction, a temperature rise of up to 5.6 K was obtained in the embedded SMP fiber after 2 s with only 1 s of the insonation. It was found that heat generation occurred at the fiber–matrix interfaces; however, subsequent temperature rise within the embedded fibers was achieved via conventional thermal conduction from the high-temperature interfacial regions into the fibers. The effect of specimen length, thickness, and fiber volume fraction on temperature rising was also evaluated. This study provides a better understanding of using ultrasound to trigger self-healing of SMP fiber-reinforced polymer composites. (paper)