摘要
采用2.25Cr—1Mo无预裂纹和带预裂纹环状缺口圆柱形试样,进行了多维应力状态下无保持周期应变控制的高温低周疲劳试验,利用有限元程序对试样缺口周围及裂纹尖端附近的应力、应变场进行了分析,分别得到用当量弹性应变范围Δε_e、当量塑性应变范围Δε_p、当量蠕变应变范围Δε_c和当量应变范围Δε表示的材料在400℃、0.2％s^(-1)应变速率下的高温低周疲劳总寿命和裂纹扩展寿命方程。利用Matlab对试验结果进行非线性多元回归,得到用疲劳成分、蠕变成分和蠕变/疲劳交互作用成分三者的非线性组合来表征的材料无保持周期应变控制的疲劳总寿命和裂纹扩展寿命评价方程,即认为整个试样的失效过程中存在着蠕变/疲劳交互作用,正是这种蠕变/疲劳交互作用的存在导致了试样或构件的疲劳总寿命和裂纹扩展寿命的降低,定量的表征了蠕变/疲劳交互作用对材料疲劳总寿命和裂纹扩展寿命的影响。
Fatigue experiments under high - temperature low - cycle state were carried out by using 2. 25Cr - 1 Mo cylinder specimens with ring notch, while some with precrack. By adopting finite element program, the stresses and strains around the notch of the specimen or near the crack tip were calculated. The fatigue life and fatigue crack propagation life of the material under 400℃, 0.2% s-1 strain rate were expressed by the equivalent elastic strain range ,the equivalent plastic strain range p, the equivalent creep strain range ec and the equivalent strain range , respectively. The data of experiment were processed by muluvariate nonlinear regression analysis using Matlab program and the fatigue life and fatigue crack propagation life under the strain control without holding time could be described by the nonlinear combination of the fatigue component, creep component and creep - fatigue interaction component. That is to say, the creep - fatigue interaction is existent in the course of failure, and the fatigue life and fatigue crack propagation life become lower due to its existence. So the effects of the kind of interaction on the fatigue life and fatigue crack propagation life are quantitatively characterized.
出处
《石油化工高等学校学报》
CAS
2003年第4期40-43,共4页
Journal of Petrochemical Universities
基金
辽宁省自然科学基金项目(962032)
