Issue 35

A. Vshivkov et alii, Frattura ed Integrità Strutturale, 35 (2016) 57-63; DOI: 10.3221/IGF-ESIS.35.07 57 Focussed on Crack Paths Experimental study of heat dissipation at the crack tip during fatigue crack propagation A. Vshivkov, A. Iziumova, O. Plekhov Institute of Continuous Media Mechanics UB RAS, 614014 Perm, Russia vshivkov.a@icmm.ru J. Bär University of the Federal Armed Forces, Institute for Materials Science, 85577 Neubiberg, Germany A BSTRACT . This work is devoted to the development of an experimental method for studying the energy balance during cyclic deformation and fracture. The studies were conducted on 304 stainless steel AISE and titanium alloy OT4-0 samples. The investigation of the fatigue crack propagation was carried out on flat samples with different geometries and types of stress concentrators. The heat flux sensor was developed based on the Seebeck effect. This sensor was used for measuring the heat dissipation power in the examined samples during the fatigue tests. The measurements showed that the rate of fatigue crack growth depends on the heat flux at the crack tip. K EYWORDS . Heat flow; Fatigue crack; Dissipated energy. I NTRODUCTION oday, the investigation of material durability is the research trend of vital importance. Different types of structures have bottleneck areas, whose destruction can lead to irreversible consequences. Material durability is the problem of current concern due to universal use of structures and mechanisms, whose resources are not endless. The issue of timely replacement of these devices is a compromise between the prevention of catastrophic consequences and economic efficiency. Any real engineering construction contains stress concentrators, welded joints and other potential sources of defects. The analysis of the kinetics of damage accumulation, the process of crack nucleation and kinetics of the crack development allows specialists to predict the time of structure failure and to perform in proper time a partial replacement or repair of deteriorated units of complex structures. Moreover, the repair or replacement of the worn-out parts on a timely basis is more effective than their complete replacement after mechanical damage. It is therefore very important to know the time during which the defects in the ill-behaved areas are reaching critical values. Theoretical and experimental study of the processes accompanying the evolution of the material structure during its deformation and fracture is an actual problem of modern experimental mechanics. Its solution enables researchers to gain deeper insight into the nature of the fracture processes and to develop new, high-performance techniques for assessing T