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依据疲劳过程中结构钢力学性能的变化规律，从反映疲劳损伤机理、对损伤过程表现敏感且便于实验测试等方面对上述材料弹性、塑性、强度和韧性等参量进行综合考察后指出，韧性是一个适合作为疲劳损伤表征的力学参量，并进一步建立了韧性随疲劳损伤演化的耗散模型。从交变载荷下材料韧性耗散规律出发，结合疲劳损伤的能耗过程分析，系统研究并提出了以韧性为基本参量的疲劳损伤变量、损伤临界值、损伤演化方程和累积损伤模型，据此建立了一种新的疲劳损伤定量方法，并在实验中得到了验证。通过与其它方法比较表明：根据韧性耗散定义损伤变量优于基于延性、强度和弹性模量变化的损伤度量方法，由此得到的累积损伤模型较Ｍｉｎｅｒ线性法则与Ｍａｎｓｏｎ双线性累积损伤法则更符合实验结果。因此，上述疲劳损伤定量方法可为现阶段工程结构的抗疲劳设计与寿命估算提供新的研究手段
According to the variation law of the mechanical properties of structural steel during fatigue process, it is pointed out that the toughness is one from the aspects of reflecting the mechanism of fatigue damage, being sensitive to the damage process and facilitating the experimental testing. Which is suitable as a mechanical parameter for the characterization of fatigue damage and further establishes a dissipative model of the ductility with the evolution of fatigue damage. Based on the law of material toughness dissipation under alternating load and combined with energy consumption process analysis of fatigue damage, fatigue damage variables, damage thresholds, damage evolution equations and cumulative damage models based on toughness are systematically studied and proposed A new quantitative method of fatigue damage was established and validated in experiments. Comparing with other methods, it is shown that the damage variables are defined better than the ones based on ductility, strength and elastic modulus. The cumulative damage model obtained by this method is better than Miner’s linear law and Manson bilinear cumulative damage law In line with the experimental results. Therefore, the above quantitative method of fatigue damage can provide a new research method for the anti-fatigue design and life estimation of the engineering structure at the present stage