第七章测试1.
The High-temperature fatigue is （ ）
A:Below 60 percent of the absolute melting temperature B:Below 50 percent of the absolute melting temperature C:More than 20 percent of the absolute melting temperature D:More than 40 percent of the absolute melting temperature
答案:D
2. Temperature influence on fatigue strengths （ ）
A:108 cycles may be a reasonable value for obtaining a long-life fatigue strength B:The fatigue strength continuously decreases with cycles to failure C:Metals at high temperatures do not usually show a fatigue limit D:Temperature influence is small 3. The description of Neuber’s rule is as follows （ ）
A:Fine-grain materials tend to give higher fatigue resistance B:Coarse-grain materials give higher creep resistance C:Fine-grain materials tend to give higher fatigue resistance D:Coarse-grain materials give higher creep resistance 4. As the hold time increased, the life decreased drastically at both test strain ranges. （ ）
A:对 B:错 5. Both frequency and temperature will affect the fatigue resistance of materials. （ ）
A:对 B:错
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