Clathrate hydrates (CHs) are promising molecular structures for versatile applications such as gas capture and storage, cold storage, and gas separation. Understanding the mechanical responses is of importance for utilizing and predicting the stability of their formations, but remains very limited. Here, mechanical characteristics of CHs entrapping a variety of gas molecules are investigated by molecular dynamics (MD) simulations. All studied CHs are structurally stable host–host hydrogen (H)-bonds yet show distinct host–guest interaction energies under load-free conditions. Tension MD simulations reveal that the tensile strength and Young’s modulus of CHs depend not only on the size and shape of guest molecules but also on their polarity; however, all CHs undergo brittle fracture on either the (0 0 1) or (1 0 1) plane also relying on the type of guest molecules. Interestingly, elastic deformation of CHs causes a reduction in the number of H-bonds, yet stronger interaction of specific triatomic guest molecules@512 with the surrounding host-water molecules, in contrast to the case of those @51262. Structural analysis shows that multiatomic guest molecules@cages uniquely reorient due to misshaping of cages, and H-bonded angular deformation of water-cages plays a more crucial role in the elastic responses of CHs than straining of H-bonds.

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The catenary system was an important part of electrified railway, which provided traction power for electric trains. Cu/CF/phenolic resin contact strip (CFRCS) had been designed with excellent mechanical strength and electrical conductivity. The properties of CFRCS and the pure carbon contact strip (PCCS) were also compared. It could be found that CFRCS not only had higher impact strength than PCCS, but also had lower resistivity, which was favorable for current transmission. This paper analyzed the wear behavior of contact strips from two aspects of wear data and abrasive dust, which was mainly determined by the current and its components. The current-carrying wear mechanism of CFRCS was mainly arc erosion wear, oxidation wear and adhesive wear, while that of PCCS was oxidation wear and arc erosion wear.

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