  The most recent experimental advances could provide ways for the fabrication
of several atomic thick and planar forms of boron atoms. For the first time, we
explore the mechanical properties of five types of boron films with various
vacancy ratios ranging from 0.1 to 0.15, using molecular dynamics simulations
with ReaxFF force field. It is found that the Young's modulus and tensile
strength decrease with increasing the temperature. We found that boron sheets
exhibit an anisotropic mechanical response due to the different arrangement of
atoms along the armchair and zigzag directions. At room temperature, 2D Young's
modulus and fracture stress of these five sheets appear in the range 63 N/m and
12 N/m, respectively. In addition, the strains at tensile strength are in the
ranges of 9, 11, and 10 percent at 1, 300, and 600 K, respectively. This
investigation not only reveals the remarkable stiffness of 2D boron, but
establishes relations between the mechanical properties of the boron sheets to
the loading direction, temperature and atomic structures.
