Initial post-buckling analysis of a fixed–fixed strut

Abstract

In this paper, the initial post-buckling of a fixed–fixed strut in compression at the first bifurcation point is analyzed. Using the Fourier series of the lateral deflection, the second variation of the potential energy is proved, analytically, to be semi-positive definite when the compression is equal to the Euler critical load. The fourth variation of the potential energy is positive when the disturbance of the lateral deflection matches the buckling mode. Based on Koiter’s initial post-buckling theory, the equilibrium of the straight state of the strut is stable at the stability limit; when the compression slightly exceeds the Euler critical load, the curved shape at initial post-buckling is stable.