This study aims to investigate the effects of sudden loads on the fatigue characteristic 60° V-notched shaft of S45C steel under constant and sudden amplitude loads, and to identify the fracture surface.
The fatigue tests were performed using rotary bending machine that was equipped by the sudden load equipment. The cyclic load was varied in three configurations, i.e constant amplitude load and two combination of sudden loads. The combination of sudden loads were designed with 84 and 52 cycles ON and OF periodically. The sudden load causes the stress increase to 76 MPa. The stress concentration factor on the V.. notched shaft was determined using finite element model.
The S-N curve of three load configurations shows that stress amplitude of 154 MPa (35% a,. or 21% au), 108 MPa (25% o or 15% au) and 28 MPa (6% ay or 4% au) cause the materials fail above 1,6.106 cycles. In that cycle, the value of stress amplitude under combination loads decreases 70,13% and 18,18% compared to constant amplitude load. The fracture surfaces under sudden load have rougher and more brilliance of beach mark. Similarly, the failures under higher stress have rougher fracture surface
