Mechanical Response and Motion-Mode Dependence of Phonon-Mediated Energy Dissipation in Si–MoS2–Si Sandwich Structure

Abstract Building on previous studies of monolayer MoS2, this work constructs an atomistic Si–MoS2–Si sandwich structure and investigates its mechanical response and phonon-mediated energy dissipation under interfacial confinement. The tensile results show that the mechanical strength of the sandwich structure gradually decreases as the Si–MoS2 interfacial spacing decreases within the range examined. During fatigue loading, the constraining effect of the Si atomic layers suppresses the out-of-plane deformation of the MoS2 nanosheet and dissipates part of the input energy through lattice vibrations, thereby improving the mechanical stability and fatigue performance of the sandwich structure. However, when fatigue resonance is induced by the external cyclic loading, the central MoS2 nanosheet still fails rapidly. Regarding frictional behavior, two relative motion modes between the upper and lower Si atomic layers and the central MoS2 nanosheet are examined: linear motion and reciprocating motion. Compared with linear motion, reciprocating motion produces a higher degree of phonon-mode matching between the Si atomic layers and the MoS2 nanosheet, facilitating the formation of efficient energy-dissipation pathways and resulting in greater frictional energy dissipation. In addition, owing to the resonance effect, the frictional energy dissipation exhibits a pronounced peak characteristic near the fatigue resonance frequency. This study provides theoretical guidance for the application of two-dimensional materials in atomically layered sandwich structures.