Dynamic control of in situ crack healing in metals under thermal and vibrational stimuli

Cracks formed in metallic materials during service degrade their performance and structural reliability. In this study, molecular dynamics simulations were used to investigate in situ crack healing, although related concepts in practice are only partial implemented in indirect ways, under thermal and vibrational stimuli. The in situ crack healing was analyzed in three aspects: material properties, crack geometry, and external dynamic regulation. Results of the study show that the critical healing temperature correlates with diffusion activation energy, surface energy, melting point, and electron work function. Temperature-induced phonon softening, coupled with crack-induced local vibrational softening, enhances atomic mobility and enables rapid crack closure near the critical temperature. Parabolic cracks exhibit accelerated healing due to reduced atomic migration distances at tapered tips. For wide cracks, thermal activation alone is insufficient. However, periodic external vibrations significantly reduce the required healing temperature and exhibit strong frequency selectivity, arising from dynamic matching between vibrational and atomic migration timescales. Overall, crack healing in metals is governed by the coupled effects of material properties, crack geometry, and external dynamic regulation, with vibration acting as an important additional control mechanism. This work provides a fundamental framework for understanding metallic self-healing and guiding clues in engineering practice.