Relation between Internal Friction and Fatigue

Abstract

Solids show the feature of internal friction and the feature of fatigue. As a cause for the both features we assume the migration of atomic items. The driving forces for the migration of the atomic items can be mechanical stress gradients and temperature gradients. In an earlier publication formulas have been derived for the internal friction and for the fatigue. From these formulas follows a relation between internal friction and fatigue. The mechanical stress gradients are the cause of the background of internal friction which shows a monotonous rise with temperature. Temperature gradients in the solid can be produced by total internal friction. In contrast to the background of internal friction the temperature dependence of the total internal friction shows maxima and minima. Because of the relations between internal friction and fatigue the temperature dependence of fatigue shows that the fatigue is caused by temperature gradients. The relation between internal friction and fatigue also shows the influence of the internal friction on the fatigue curve.

Simulating Fatigue Crack Growth including Thermal Effects Using the Phase Field Method

“…Internal friction happens inside of a deformed body, and it is the internal force resisting the movement between the particles making up a solid body. Internal friction can be influenced by the frequency of the cyclic loading and the thermal state of the loaded material [23] [15] [16]. Recently, Gräfe [15] proposed that there exists a relation between internal friction and fatigue of solids.…”

“…Recently, Gräfe [15] proposed that there exists a relation between internal friction and fatigue of solids. On the one hand, the internal friction can be caused by the motion of defects by the stress field [16]. The dislocations of atoms in the solid destroy chemical bonds, which is shown macroscopically as the fatigue of material [16].…”

“…On the one hand, the internal friction can be caused by the motion of defects by the stress field [16]. The dislocations of atoms in the solid destroy chemical bonds, which is shown macroscopically as the fatigue of material [16]. On the other hand, the temperature gradient, generated by the internal friction, can be also seen as a driving force for the movement of the unspecified defects in the solid.…”

“…Recent studies [15] [16] showed that there is a relation between internal friction and material fatigue: different kinds of particle migration can be seen as a source of fatigue processes. However, there is still no physical model that can simulate all the effects of internal friction on fatigue behavior in complex circumstances.…”