A negative eigenvalue in a buckling analysis may imply that the buckling load is in the opposite direction of the applied load. For example, for a simply supported beam, if a tensile axial load is applied to one end, then the eigenvalue will be negative.
One the other hand, for a cylinder that is subjected to a torsional load, a negative eigenvalue implies that another possible buckling mode is in the opposite direction of the applied load. In this case, since the cylinder is symmetric, the structure can buckle torsionally either with a clockwise load or counterclockwise load.
Similarly, a slender beam that is subjected to a vertical load can buckle laterally to the left or right, yielding positive/negative pairs of eigenvalues.
Recent Comments