13th International Conference on Fracture June 16–21, 2013, Beijing, China -6- (a) At the loading amplitude of 7MPa (b) At the loading amplitude of 9MPa Fig. 8 Comparison of the hysteresis loops at the temperature of 325℃ and 225℃ 3.2.2 Fatigue life prediction The stress-life (S-N) data can be plotted linearly in a log-log scale which is firstly observed by Basquin [12]. Here the formula can be expressed as ∆τ/2ൌ ߪ , ௧ሺ2ܰ ሻ (Eq. 1) The relationship between the shear stress amplitude and the fatigue life for sintered nano-silver lap shear joint at 325℃ and 225℃ are linearly fitted as Basquin’s equation in the logarithm coordinate system as shown in Fig. 9. The fatigue strength exponent b and fatigue strength coefficient ߪ , ௧ for sintered lap shear joint are given in Table 2. It can be obviously observed that the fatigue strength coefficient increased with decreasing temperature. The fatigue strength exponent has little change at different temperature as is shown in Fig. 9. The fatigue life of the nano-silver sintered lap-shear joints at the temperature of 325℃ and 225 ℃ are fitted well. Fig. 9 S-N curve for nano-silver sintered lap-shear joints -3-2-1 0 1 2 3 Shear strain(%) -10 -5 0 5 10 325oC-10Cycles 225oC-10Cycles Shear stress(MPa)
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