Abstract: Based on the geometrically non-linear buckling theory of large deflection elastic beams, the governing differential equations of post-buckling of a symmetrical clamped-clamped beam with oblique angles, subjected to a combined load, are established. By using the latent restraint conditions of post-buckling deformation of the elastic beam, the strong nonlinear boundary value problems are numerically solved and the exact solutions in the numerical sense are obtained directly. The non-linear transverse stiffness and the post-buckling configurations during the periods of initial buckling, post-buckling and snap-through process of the beam with different angles are presented. According to the principle of minimum energy and the number of inflexion points along the deflection curve, the inward relation of different buckling mode and its influence on the structural stiffness are analyzed systematically, and the transformation condition for the different buckling modes are obtained. While the oblique buckled beam deflects largely, the obvious bistability and the low order buckling modes (the first and the second) are shown by the numerical simulation results which are consistent with those obtained by experiments.

Key words: Bistability, Geometrical nonlinearity, Large deflection, Post-buckling, Snap-through