Study on Damaging and Fatigue Life of Constructions under Single- and Two-Frequency Loading Modes Based on Deformational and Energy Approaches

The damage accumulation patterns under one- and two-frequency loading modes were studied on the basis of deformation and energy failure criteria under elastoplastic cyclic deformation. It is demonstrated that the change in fatigue life upon applying a high-frequency component of strains (deformations) to the basic low-cycle process can be determined from the sum of fatigue damage components from basic and applied deformation or the observed coefficient of breaking cycle number decrease, depending on the relations between frequencies and amplitudes of interacting cyclic processes. With regard to this, the components of damage due to cyclic deformations are related to the energy characteristics of the deformation processes studied, including the mechanical energy expended on the deformation process, the thermal energy released (determined by measuring the self-heating temperature change), and also the energy absorbed before the fracture.