Fatigue fracture surface of bronze RG7 under proportional cyclic torsion and bending

Abstract

The paper presents the results of fatigue cyclic tests performed on MZGS stand of RG7 bronze under symmetric bending, symmetric torsion, and the combination of proportional symmetric bending and torsion, where τa = σa and τa = 0.5σa. Causes of damage were determined by scanning electron microscopic observation. The fracture images were observed using a Tescan Vega 4 Scanning Electron Microscope operating at 20 kV. Secondary electron detection (SE) was used to obtain SEM images. For topographic analysis, an optical profilometer by Sensofar 3D S neox was used, which includes modern software for surface analysis by Digital Surf Mountains Map. Fatigue crack analysis was performed by observing samples for each combination under the following scheme: one with a low load level with a lifetime of 1,000,000 cycles and the other with a high load level and a lifetime of 30,000 cycles.