13th International Conference on Fracture June 16–21, 2013, Beijing, China -7- Table 2. Comparison of fatigue properties between experimental value and empirical value Temperature (℃) ߪ , ௧ B 225 19.2 15.3 -0.1056 -0.1061 325 3.3 The dwell-fatigue behavior of nano-silver sintered lap-shear joints As listed in Table 2, a series of dwell-fatigue tests (A7-A11) are conducted at the loading amplitude of 6MPa and the temperature of 325℃. From the results show in Table 3 we can find that with the increasing of dwell time, the fatigue life in cycle decreases at a rapid rate. But the total creep time (dwell time summation) holds between 2000-4000s, which indicates that the creep take a more important part in the failure process and might lead to the final failure. A point should be put forward that dwell sensitivity accelerates the fatigue failure while the cyclic loading prolong the creep life, since the creep life of the joints under the same loading amplitude is only 415s. Table 3. The dwell-fatigue tests data under different dwell time. Spec. ID Temperature /℃ Dwell time (s) Fatigue Life (cycles) Total creep Time (s) A6 325 0 6925 0 A7 325 1 2538 2538 A8 325 3 1226 3678 A9 325 5 438 2180 A10 325 7 536 3752 A11 325 9 239 2151 B4 225 0 9800 0 B5 225 1 4590 4590 B6 225 7 919 6433 B7 225 9 409 3681 Fig.10 indicates that the number of cycles verses dwell time is a straight line on the semi-log plot. The life in cycles reduces with the increasing of dwell time. It should be pointed out that the effect of dwell time at the temperature of 325℃ is more significant than that of 225℃. In other words, as the creep behavior of nano-silver sintered lap-shear joints is significantly influenced by temperature, so creep plays a more important part to the final failure of specimens at the temperature of 325℃ than 225℃. However, a series of creep-fatigue tests need to be conducted for further study of the effect of creep on creep-fatigue tests.
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