Edward Saibel

Thermal aspects of galling of dry metallic surfaces in sliding contact

Abstract The phenomenon of galling or seizing of metals is believed to be, in general, a function of the thermal and mechanical conditions under which the metallic surfaces are rubbed together. For polished surfaces, under ideal dynamic conditions, i.e., conditions where the surfaces are devoid of appreciable oscillations in the direction normal to the surfaces, thermal aspects of galling predominate. Galling due to thermal conditions is viewed as that condition where the tips of surface asperities weld together and are then sheared apart according to the weld-junction or adhesion theories. Welding may be achieved when the melting temperature is reached; also when surface asperities, which are under a high degree of strain, are in sliding contact. Welding may be achieved by recrystallization recovery. The latter process is taken as the governing condition for thermal galling since the recrystallization temperature is only a fraction of the melting temperature. The galling criterion, relating normal load, velocity, and time of rubbing, is established theoretically. The result compares favorably with experience.

Buckling of continuous beams on elastic supports

Abstract The continuous beam having elastic intermediate supports, equally spaced and of equal stiffness, is solved for the condition that they behave as rigid supports when the beam buckles under the action of an axial compressive force. The exact solution is given in closed form.