基于能量耗散的Q235钢高周疲劳性能评估

High Cycle Fatigue Behavior Evaluation of Q235 Steel Based on Energy Dissipation

通过宏微观力学和连续热力学理论,推导疲劳能量耗散计算方法。结合局部热扩散方程,建立物理意义明确的疲劳极限快速评估方法,避免了以温升为损伤指标的预测方法的争议性。传统疲劳试验和本方法所给出的疲劳极限之间的误差为9.9%,表明了该方法的准确性。试验过程表明当材料内部生热率与外界散热率达到平衡时,能量耗散的变化趋于稳定,由此确定了材料的极限能,构建了疲劳寿命的快速评估方法。结果发现所预测的S-N直线斜率与传统结果之间的误差为9.4%,从而表明了该方法在快速评估材料疲劳性能方面的潜在前景。

Using the theories of macro micro mechanics and continuum thermodynamics, the energy dissipation calculation method is derived for high-cycle fatigue evaluation. The local heat diffusion equation is used to create a method for rapid fatigue limit evaluation. This method with definite physical meaning eliminates the arguments on the thermographic method. Fatigue limits by the traditional tests and the present method are compared, and an error of 9.9% is given, showing the accuracy of this method. It is shown that in the process of fatigue when the heat generation rate is equal to the heat dissipation rate, the energy dissipation tends to be an asymptotic value. Therefore, the limiting energy is determined as the product of the energy dissipation and the whole fatigue life, and a method for rapid fatigue life prediction is developed. It is noted that the slope of the predicted S-N curve, with an error of 9.4%, is in good agreement with the traditional result. Consequently, the potential prospect of the present method in rapid fatigue behavior evaluation is presented.