尹涛, 蔡力勋, 陈辉, 姚迪. TA17合金薄片材料毫小试样疲劳性能研究[J]. 工程力学, 2018, 35(11): 206-215. DOI: 10.6052/j.issn.1000-4750.2017.08.0607
引用本文: 尹涛, 蔡力勋, 陈辉, 姚迪. TA17合金薄片材料毫小试样疲劳性能研究[J]. 工程力学, 2018, 35(11): 206-215. DOI: 10.6052/j.issn.1000-4750.2017.08.0607
YIN Tao, CAI Li-xun, CHEN Hui, YAO Di. STUDY ON FATIGUE PROPERTIES OF TA17 ALLOY SLICE BY MILLIMETER-SIZED SPECIMEN[J]. Engineering Mechanics, 2018, 35(11): 206-215. DOI: 10.6052/j.issn.1000-4750.2017.08.0607
Citation: YIN Tao, CAI Li-xun, CHEN Hui, YAO Di. STUDY ON FATIGUE PROPERTIES OF TA17 ALLOY SLICE BY MILLIMETER-SIZED SPECIMEN[J]. Engineering Mechanics, 2018, 35(11): 206-215. DOI: 10.6052/j.issn.1000-4750.2017.08.0607

TA17合金薄片材料毫小试样疲劳性能研究

STUDY ON FATIGUE PROPERTIES OF TA17 ALLOY SLICE BY MILLIMETER-SIZED SPECIMEN

  • 摘要: 关键工程结构、小尺寸零部件和焊接区的疲劳寿命评估中往往无法采用传统大试样进行疲劳试验,因此本文提出了一种采用毫米级别薄片试样获取材料循环本构关系和低周疲劳寿命的新方法。在Care原位试验机上完成毫米级别薄片漏斗试样的加载工装和低周疲劳试验的基础上,通过变幅对称循环试验和等辐循环试验分别实现了材料循环本构关系和低周疲劳性能的获取。该文提出了一种对不同幂律材料和不同几何尺寸构型均具有良好普适性的材料循环本构关系预测模型,并通过有限元实现了模型准确性的正反向预测验证。将循环本构关系用于有限元计算中,给出了薄片漏斗试样漏斗两侧名义应力、名义应变和漏斗根部真实应力、真实应变的转换方程,进而预测材料的低周疲劳寿命。该文完成了TA17合金等直圆棒试样和1.2 mm厚度薄片漏斗试样的对称变幅循环试验和多级等辐循环试验。由模型预测获得的TA17合金循环本构关系与等直圆棒试样的试验结果比较表明:两种曲线的弹性段和0.009 mm/mm~0.011 mm/mm应变段吻合良好,在弹塑性过渡段(0.004 mm/mm~0.009 mm/mm)模型预测结果最大相对误差小于9%。根据两组应力和应变转换方程获得的漏斗试样材料代表性体积单元疲劳寿命和Manson-Coffin寿命预测模型与等直圆棒试样试验结果均吻合良好。

     

    Abstract: It is difficult to obtain the fatigue properties of key engineering structures, small sized parts and welding areas by using low cycle fatigue testing specimens which are given by current standards. In this paper, a new method is proposed to obtain the cyclic constitutive relationship and low cycle fatigue life of materials by using a millimeter-sized specimen. The low cycle fatigue test of TA17 alloy slice is carried out by designing semicircular notched slice specimens, loading fixture and testing scheme. Based on the assumed strain energy separation function, a universal prediction model of cyclic constitutive relationships is proposed. The forward and backward prediction of finite element simulations show that the new model has universal validity for different power-law materials and different dimensions of notched slice specimens. Symmetric strain-controlled variable-amplitude low cycle fatigue tests and multi-level low cycle fatigue tests of TA17 alloy straight round bar specimens and 1.2 mm thickness notched slice specimens are completed. After using the cyclic constitutive relationship of TA17 alloy predicted by the new model to compare with straight round bar specimens, the results show that they are in a good agreement with elastic segments and the large strain segments (0.009 mm/mm~0.011 mm/mm), and that their maximum relative predicting error is less than 9% in elastic-plastic transition segments (0.004 mm/mm~0.009 mm/mm). Adopting the finite element method based on the cyclic constitutive relationships obtained by the new model and straight round bar specimens, two sets of transforming equations are conducted to convent the testing strain amplitude and average stress amplitude of notched slice specimens to axial strain and stress amplitude at the semicircular notched root. Finally, the notched slice specimens' fatigue-life curves of material representative volume element and Manson-Coffin life prediction model via two sets of transforming equations are verified to be identical to the experimental results from straight round bar specimens.

     

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