REPUBLIC OF SERBIA

MINISTRY OF DEFENCE

www.mod.gov.rs

MINISTRY OF DEFENCE

Material Resources Sector

Defensive Technologies Department

Military Technical Institute

www.vti.mod.gov.rs

THE BEHAVIOUR OF BASE MATERIAL AND WELDED JOINT OF STEEL NN - 70 IN THE CONDITIONS OF VARIABLE LOAD

DŽENANA GAČO

University of Bihać, Bihać, Bosnia and Herzegovina, dzenana.gaco@unbi.ba

BAHRUDIN HRNJICA

University of Bihać, Bihać, Bosnia and Herzegovina, bahrudin.hrnjica@unbi.ba

fadil islamović

University of Bihać, Bihać, Bosnia and Herzegovina, fadil.islamovic@unbi.ba

ZIJAH BURZIĆ

Military Technical Institute, Belgrade, Serbia, zijah.burzic@vti.vs.rs

Abstract: Characteristics that describe the occurrence and growth of the cracks under the influence of variable load are the most important for the exploitation safety of welded structures. Metal fatigue is defined as a process of joint failure under the influence of variable load, which is expressed by the occurrence of fatigue crack and fracture. The fatigue test results are influenced by a large number of factors, so the choice of type and load regime, cycle parameters, tubular shape, number of cycles, criteria for evaluation (the appearance of the first macro-fractures, the reduction of the load, the fracture) are very important.

Keywords: impact testing, variable load, metal fatigue, dynamic strength.