Mechanical Properties of Methane Hydrate: Intrinsic Differences from Ice

Understanding fundamental mechanical behaviors of ice-like crystals is of importance in many engineering aspects. Herein, mechanical characteristics of monocrystalline methane hydrate (MMH) and hexagonal ice (Ih) under mechanical loads are contrasted by atomistic simulations. Effects of engineering strain rate, temperature, crystal orientation, and occupancy of guest molecules on the mechanical properties of MMH are investigated. Results show that the engineering strain rate, temperature, and occupancy of guest molecules in 51262 cages greatly affect the mechanical strength and failure strain of MMH, whereas the effect of crystal orientation on the tensile response of MMH such as along the [100] and [110] directions is negligible. Particularly, the occupancy of guest molecules in 51262 cages primarily governs the mechanical strength and elastic limits of MMH. For Ih, it is tensile stiffer than that of MMH at 263.15 K and 10 MPa, and shows unique mechanical characteristics such as tension-induced stiffenin...