In Euler's equasion is the critical buckling load the force that will initiate a bend in the column, or is it the force that leads to catastophic failure. If we start with the initial assumption that there is some lateral force due to system imperfections to initiate the buckling. It seems an infinitely small axial force causes an infinitely small bend, and a moderate axial force causes a moderate bend that is stable and the member returns to its original shape when the force is removed. Does a coulmn "bend" before it "buckles"? Has buckling occured if the column springs back after the load is removed, or have we not yet reached the critical buckling load?