摘要
给出了几种典型拉-扭加载路径在新定义主坐标系下的π平面投影路径,并基于π平面投影路径提出了一种新的多轴疲劳损伤参量;考虑材料多轴加载的非比例附加强化效应,提出了一种非比例附加强化系数的预测方法和非比例度的定义方法;进一步考虑缺口试样多轴加载下的拉-扭应力梯度分布,结合有限元弹性分析的结果,提出了一种考虑多轴效应的等效应力梯度因子,从而发展了一种新的考虑应力梯度影响的多轴缺口疲劳寿命预测模型,并选用GH4169合金650℃下的多轴缺口疲劳试验结果对所提出的寿命模型进行验证。结果表明:(1)所提出的多轴疲劳损伤参量有明确的物理意义,不仅适用于多轴疲劳,也适用于单轴疲劳;(2)所提出的等效应力梯度因子仅需通过弹性有限元分析确定,适合工程实际应用;(3)新的寿命预测模型对GH4169材料多轴缺口疲劳试验的寿命预测结果较好,基本位于2倍分散带以内。
The projection paths on theπ-plane under the newly defined principal coordinate system of several typical tension-torsion loading paths were given.A new multiaxial fatigue damage parameter was proposed based on the projection path on theπ-plane.With the non-proportional additional hardening effect being considered,aprediction method of the non-proportional cyclic hardening coefficient was proposed and a new non-proportionality description was defined.Furthermore,a multiaxial effective stress gradient factor was defined by combining the tension stress gradient and the torsion stress gradient of finite element elastic analysis,and a multiaxial notch fatigue life prediction model was developed based on the multiaxial stress gradient effect.The multiaxial notch fatigue test results of GH4165 alloy at650℃ were used to verify the proposed model.On the basis of analytical study,conclusions can be drawn as follow:(1)the proposed multiaxial fatigue damage parameter is suitable for multiaxial fatigue and uniaxial fatigue with a clearly physical meaning;(2)the equivalentstress gradient factor can be determined only by elastic finite element analysis,which is suitable for practical application;(3)the predicted multiaxial fatigue lives of GH4169 alloy using the proposed model agree better with the experimental results,which are almost within two-time scatter band of the test results.
出处
《航空动力学报》
EI
CAS
CSCD
北大核心
2018年第11期2602-2610,共9页
Journal of Aerospace Power
基金
国家自然科学基金(51475024)
关键词
多轴缺口疲劳
寿命预测
应力梯度
π平面
非比例附加强化
multiaxial notch fatigue
life prediction
stress gradient
π-plane
non-proportional additional hardening