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针对缺口试样在高温条件下局部区域应力应变难于测量的问题,基于光滑试样材料力学性能试验,优化得到550℃粉末高温合金FGH97的Chaboche黏塑性统一本构方程参数,并将其应用到FGH97缺口试样单调拉伸及循环加载弹塑性有限元分析中.研究结果表明:①缺口局部区域进入塑性后其应力分布与弹性条件明显不同,随应力增大,最大应力位置向内移动;②在循环载荷条件下,随着循环数的增加,缺口平分线上应力/应变范围变化不大,缺口根部塑性区域出现明显平均应力松弛,并逐渐趋于稳定,导致缺口根部循环载荷比不同于外部施加载荷;③缺口根部塑性区域逐渐增大,但增大的幅度逐渐降低.该研究可为进一步分析缺口构件疲劳寿命影响因素提供支持.
In view of the difficulty of measuring the stress and strain of the notched specimens in the local area under high temperature conditions, the unified Chaboche visco-plastic constitutive equation of 550 ℃ powdery superalloy FGH97 was optimized based on the mechanical properties of the specimen. The results show that: (1) The stress distribution and elastic conditions of the notched local area are obviously different after entering the plastic, and the maximum stress position moves inward when the stress increases; Under the cyclic loading condition, with the increase of the number of cycles, the stress / strain range on the notched bisector changed little, and the average plastic stress relaxation at the notch root appeared and gradually stabilized, resulting in the cyclic loading ratio at notch root being different from the externally applied And the plastic zone of notch root increased gradually, but the increasing amplitude gradually decreased.This study can provide support for further analysis of the influencing factors of the fatigue life of notched members.