A nondestructive test technique which has the potential for measuring the degree of fatigue in military bridge structures has been identified by us. The technique is called internal friction damping nondestructive evaluation. The physical property that is monitored in this technique is the rate at which an energy impulse imparted to a material or structure decays due to the internal friction of the material. A change in the rate of decay reflects changes in the basic chemical and/or mechanical properties of the material due to an accumulation of subtle material variables. These material variables include the grain size, chemical compositions, interstitial elements, dislocations, precipitate particles, strain rate effects, etc. By proper monitoring of the accumulation of these insidious variables, it is
