为评估抗疲劳主要参量对S-N曲线的作用规律,采用双参数疲劳寿命模型作为分析基础,引人材料本征S-N曲线概念,将制造参量转化为制造结果参量系数,在从理论模型角度系统分析各个参量对寿命曲线的作用规律的基础上,进一步对实验获得的高温合金GH4169在成型机加工、表面完整性机加工和表面高能强化三种制造工艺下的疲劳S-N数据进行疲劳抗力系数Mf和理论疲劳极限Sc对应力集中系数Kt的敏感性进行分析.结果表明:高能强化可显著提高光滑试样和缺口试样的疲劳性能;对于光滑构件或低应力集中系数的构件,高能强化对疲劳性能的提高主要表现在提高了疲劳抗力系数;而对于高应力集中系数的构件,高能强化对疲劳性能的提高主要表现在提高了理论疲劳极限;此外,利用结果参量系数分析S-N曲线的方法,对于理解抗疲劳制造机理具有重要参考价值.
A new concept of intrinsic S-N curve was proposed.Then influencing factors caused by manufacture were introduced based on fatigue life double-parameter model and the effects of influencing factors caused by manufacture on S-N curve were discussed.GH4149 was employed to obtain S-N curves with different stress concentrations.The specimens had three surface states resulting from different manufacturing processes which are traditional machining process,machining process with surface integrity and advanced surface strengthening technology.The sensitivity of fatigue resistance coefficient (Mf) and theoretical fatigue limit (Sc) to Kt was analyzed.The results show that the fatigue properties of the smooth specimens and notched specimens both are improved after surface strengthening.When the stress concentration is relatively low,the increase of fatigue resistance coefficient (Mr) plays more important role for the improvement of fatigue life after surface strengthening.Nevertheless,the improvement of theoretical fatigue limit (Sc) becomes more and more important with the increase of Kt.Moreover,it is helpful to analyze the changes of S-N curve using influencing factors caused by manufacture for deepening the understanding of anti-fatigue manufacture.