METHOD FOR DETERMINING THE FATIGUE LIMIT OF MATERIAL Russian patent published in 2003 - IPC

FIELD: mechanical tests of materials for cyclic fatigue. SUBSTANCE: the method consists in the fact that the material specimen is cyclically loaded at a resonance frequency at a stepped increase of the level of load, beginning from the level below the fatigue limit, and the characteristic of energy dissipation at each step of loading is determined, and the fatigue limit is judged by the breakpoint of the dependence of the characteristic of energy dissipation on the level of the load. After determination of the fatigue limit at least one the stage of hardening is carried out due to the fact the load corresponding to the breakpoint of the dependence of the characteristic of energy dissipation on the level of load is reduced by 10 to 15%, and at this level of load the cycles of loading are accomplished while the natural frequency of specimen vibrations is increasing, and after its stabilization the loading is removed, the specimen under test is kept without any load for 8 to 24 h, and the cycles of loading are repeated at the same level of load during the time period of the repeated increase of the natural frequency of specimen vibrations, then the material fatigue limit is determined again, beginning from the load at which the hardening has been made. EFFECT: expanded functional potentiabilities of the method for determining the material fatigue limit, in particular enhanced fatigue limit of tested products. 2 dwg