Due to its many superior properties, bilayer graphene is expected to serve as a proper candidate in various applications, and further provokes intensive research on how it deforms. Based on atomistic simulations, the elastic behavior of bilayer graphenes, including fracture under tension and buckling under compression, is investigated under in-plane loadings. The elastic property, e.g. Young's modulus and fracture strain, of either armchair or zigzag graphene is sensitive to both chirality and loading direction when tension is applied. However, the armchair-zigzag bilayer graphene with mixed chirality has no dependency on loading direction and its tensile rupture process is in a step-by-step manner. Under different loading histories, the bilayer graphene also exhibits quite different mechanical response. These results are useful for both further investigation and potential application of graphene in nano-electromechanical systems. (c) 2012 Elsevier B.V. All rights reserved.