低周疲劳过程中的非弹性响应和热响应

Inelastic and Thermal Response during Low Cycle Fatigue Process

材料的疲劳是能量耗散过程。低周疲劳过程的非弹性响应反映了机械能耗的规律 ,而热响应则能够表征疲劳过程的热耗散规律。通过低周疲劳试验 ,研究了 40 Cr Ni Mo A在循环加载过程的软化 /硬化规律以及机械能耗规律 ,并利用细小热敏电阻测量了试样在加载过程中的温度变化以及温度涨落规律。

The fatigue of material is a process of energy dissipation. In order to study the mechanical energy dissipation, the inelastic response, including hysteresis loops, cyclic stress, cyclic hysteresis energy and accumulated plastic strain energy, was measured for the high strength alloy steel 40CrNiMoA in low cycle fatigue test. In order to study the thermal dissipation, the temperature change during low cycle fatigue was measured by a small thermistor. It is found that 40CrNiMoA is a cyclic softening material, which is indicated a the gradual decrease of the cyclic stress and the cyclic hysteresis energy. The accumulated plastic energy depends on the fatigue life. The temperature of the specimen increases steadily during the fatigue process, but fluctuates within a load cycle. There is a phase difference of about 180 degrees between the strain and the temperature. The self-heating temperature rise and the temperature fluctuation amplitude are dependent on the controlling strain and frequency.