Effects of Defect and Temperature on the Mechanical Performance of WS₂: A Multiscale Analysis

Abstract

This paper analyzes the mechanical properties of tungsten disulfide (WS 2 ) by means of multiscale simulation, including density functional theory (DFT), molecular dynamic (MD) analysis, and finite element analysis (FEA). We first conducted MD analysis to calculate the mechanical properties (i.e., Young's modulus and critical stress) of WS 2 . The influence of different defect types (i.e., point defects and line defects) on the mechanical properties are discussed. The results reveal that WS 2 has a high Young's modulus and high critical stress. Next, the effects of defect density and temperature on the mechanical properties of the material were analyzed. The results show that a lower defect density results in improved performance and a higher temperature results in better ductility, which indicate that WS 2 can potentially be a strain sensor. Based on this result, FEA was employed to analyze the WS 2 stress sensor and then fabricate and analyze the device for benchmarking. It is found that the FEA model proposed in this work can be used for further optimization of the device. According to the DFT results, a narrower band gap WS 2 is found with the existence of defects and the applied strain. The proposed multiscale simulation method can effectively analyze the mechanical properties of WS 2 and optimize the design. Moreover, this method can be extended to other 2D/nanomaterials, providing a reference for a rapid and effective systematic design from the nanoscale to macroscale.

Interplay between Thermal Stress and Interface Binding on Fracture of WS2 Monolayer with Triangular Voids

“…Therefore, by tuning the difference in TECs and interfacial bonding strength between the substrate and the monolayer, one can produce high-quality 2D materials with improved structural stability and can also achieve desired electronic and magnetic properties. Efforts have been devoted to studying the mechanical properties of 2D materials, such as elastic properties, load/stress-bearing capacity, fracture, and so on. − ,− Unfortunately, a systematic approach and an understanding of interfacial interactions between various 2D materials with defects and commercially used substrates are currently unavailable.…”

Self-Limiting Growth of Monolayer Tungsten Disulfide Nanoribbons on Tungsten Oxide Nanowires

“…If the WS 2 nanoribbons on the nanowires were strained to the same degree as those on the nanowires, the magnitude of the strain would not be large enough to mechanically destroy the WS 2 structure. 30 No strain-induced changes were observed in the PL spectra (Figure S8). These results indicate that the strain induced by the curved structure is not significant for the crystal structure or optical properties of WS 2 .…”

Modelling and Validation of the Axial Strain Distribution in WS2 Flakes at WS2/Epoxy/PMMA Nanocomposite under Axial Load

“…Outside the elastic region, these "triangle" strain distributions observed in 2D nanomaterials like graphene, MoS2, WS2 etc., could be modeled using numerical (FEM) cohesive models (Liu et al 2014) or by recently reported multiscale simulation (Tang et al 2021).…”

“…There are also known two-dimensional analytical solutions (continuum mechanics, plate theory) at mechanical and/or temperature loading in layered composite structures (single lap-joint, double lap-joint) (Zhao et al 2014), but still are not known such incorporating 2D nanoadditives or layers. Over the last years, only some research related to modelling, predicting, and controlling the stress transfer and/or strain mapping in WS2/polymer nanocomposites has been found in the literature (Zhang et al 2016;Wang 2017;Deng, Sumant, and Berry 2018;Wang et al 2020;Tang et al 2021;Falin et al 2021). In Zhang et al (2016) a finite element (FE) model of a WS2/PDMS sample under tensile strain has been represented as a strain relaxation with wrinkle formation observed on the monolayer WS2 triangular crystals at high tensile strain.…”

“…In Zhang et al (2016) a finite element (FE) model of a WS2/PDMS sample under tensile strain has been represented as a strain relaxation with wrinkle formation observed on the monolayer WS2 triangular crystals at high tensile strain. Tang et al (2021) have proposed a more complex study on multiscale simulation, including density functional theory (DFT), molecular dynamic (MD) analysis, and FE analysis in order to analyze the WS2 mechanical properties as a part of stress sensor and then fabricate and investigate the device for benchmarking. It has been found that the proposed FE model in this work can be used for further optimization of the device.…”