Advanced additive manufacturing of self-healing composites: Exploiting shape memory alloys for autonomous restoration under mixed-mode loading

Abstract

Applying Additive Manufacturing (AM) techniques has facilitated the production of innovative self-healing structures that can acclimate to environmental fluctuations by considering their damage response. This paper introduces a novel approach for fabricating AM composites reinforced with Shape Memory Alloys (SMAs) and possessing self-healing capabilities. The self-healing performance of the composites is assessed by subjecting undamaged and repaired samples to mixed mode I/II loading conditions using pre-cracked Semi-Circular Bending (SCB) specimens. Supplementary parameters that impact the self-healing process, including varied pre-strain levels of 1%, 2%, and 4.3% for SMA wires, are investigated. The outcomes of these pre-strain levels are subsequently compared to the repair scenario in the absence of SMAs. The transferred healing agent volume to the damaged region and the remaining crack opening is quantified using a thermography camera and image processing techniques. The study’s results demonstrate that self-healing can be achieved through strategic considerations of pre-strain levels in SMA strings and loading modes. Furthermore, the study suggests that neglecting such concerns may potentially have deleterious effects on layered samples' load-bearing capacity. The proposed methodology holds great promise for producing self-healing 3D-printed composite specimens in the laboratory and scaling them up to real-world applications.