13th International Conference on Fracture June 16-21, 2013, Beijing, China 420MPa to 280MPa during fatigue test process, where Nis the loading cycle, Nf is the cycles to failure (i.e. fatigue lifetime) andN/Nf represents fatigue loading cycles ratio. Dissipated energy per cycle Em d1 was almost constant after 10% of total fatigue lifetime (N/Nf=0.10) beyond σmax=370MPa) and 5% of total fatigue lifetime (N/Nf=0.05 in belowσmax=350MPa). 0.0 0.2 0.4 0.6 0.8 1.0 0 20000 40000 60000 80000 E (J.m-3.cycle-1) Normalization (n i /N f ) 420MPa N f =72,897 400MPa N f =91,580 380MPa N f =146,425 380MPa N f =149,296 350MPa N f =245,817 Em d 1 error bars Figure 5: Dissipated energy variation during high cycle fatigue tests from 420MPa to 350MPa (Rσ=0.2, f=14Hz). 0.0 0.2 0.4 0.6 0.8 1.0 0 5000 10000 15000 20000 E (J.m-3.cycle-1) Normalization (n i /N f ) 320MPa N f =277,642 310MPa N f =305,381 300MPa N f =696,100 290MPa NoFailure_2,000,000 280MPa NoFailure_2,000,000 error bars Em d 1 Figure 6: Dissipated energy variation during high cycle fatigue tests from 330MPa to 280MPa (Rσ=0.2,f=14Hz). The same phenomenon about dissipated energy variation were observed byMeneghetti, G[8, 13]. In his method, the fatigue test must suddenly stop many time to measure the cooling curves to calculate the specific heat loss Q. The 7
RkJQdWJsaXNoZXIy MjM0NDE=