Estimation of buckling loads of structural components by measurements of shifts in modal vibrations

Instability of structural components is shown to be more complicated for beams and hooks than for the classical Euler´s column condition. A normal mode vibration method is shown to be relevant to the detection of loads that approach the unstable buckling condition. The natural frequency of the mode of vibration that matches the unstable bending or torsional shape shifts from the no-load natural frequency and then returns to the no-load frequency value at the critical load for buckling. This new experimental method is proposed as a nondestructive method for complex structures when no analytical solution is available