Research on Stiffness Characteristics of Hold-down Spring Based on Johnson-Cook Constitutive Model
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摘要: 燃料组件压紧板弹簧的刚度设计对其安全服役起着至关重要的作用。通过引入INCONEL 718合金的Johnson-Cook非线性本构关系,拟合了不同中子辐照剂量下INCONEL 718合金的Johnson-Cook非线性本构模型;建立了压紧板弹簧系统的有限元模型,开展了不同因素对压紧板弹簧刚度特性的影响研究。结果表明:温度、加载次数、幅值的增大会导致压紧板弹簧在循环加载下出现不同程度的软化,而加载速率的增大会使压紧板弹簧的刚度出现硬化。本文研究可为燃料组件中的压紧板弹簧刚度设计提供参考。
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关键词:
- 压紧板弹簧 /
- 刚度特性 /
- Johnson-Cook非线性本构模型
Abstract: The stiffness design of hold-down spring in fuel assembly plays an important role in its safe service. By introducing the Johnson-Cook nonlinear constitutive relation of INCONEL 718 Alloy, the Johnson-Cook nonlinear constitutive model of INCONEL 718 Alloy under different neutron irradiation doses is fitted; the finite element model of the hold-down spring system is established, and the influence of different factors on the stiffness characteristics of the hold-down spring is studied. The results show that the increase of temperature, loading times and amplitude lead to different degrees of softening of the hold-down spring under cyclic loading, while the increase of the loading rate makes the stiffness of the hold-down spring harden. The study in this paper can provide a reference for the stiffness design of the hold-down spring in the fuel assembly. -
表 1 拉伸试样尺寸
Table 1. Tensile Specimen Size Information
试样 d0/mm L0/mm Lc/mm Lt/mm r/mm 螺纹 φ5 5 25 30 98 5 M10×1.5 φ6 6 30 35 98 5 M12×1.5 标准[9] 5 d0 ≥L0+0.5 d0 ≥Lc+4 d0 ≥0.75 d0 L0—原始标距;Le—平行段长度;Lt—总长度;r—圆弧半径;空白表示无此项,下同 表 2 弹簧材料INCONEL 718合金拉伸试验结果
Table 2. Tensile Test Results of Spring Material INCONEL 718 Alloy
试样编号 试验温度/℃ σ0.2/MPa σm/MPa A/% Z/% φ5-1-室温 20 1203 1433 25.0 45.3 φ6-1-室温 20 1208 1464 24.9 46.3 φ5-1-高温 300 1128 1367 22.9 46.2 φ6-1-高温 300 1123 1375 23.0 45.6 表 3 INCONEL 718合金J-C本构模型参数
Table 3. J-C Constitutive Model Parameters of INCONEL 718 Alloy
A B n m C 817 1059.32 0.5164 0.9333 0.1 表 4 不同中子辐照剂量下拟合的J-C本构模型参数
Table 4. Parameters of Fitted J-C Constitutive Model at Different Neutron Irradiation Doses
中子辐照剂量/dpa A B n m C 0 724 1078 0.56 0.933 0.8 0.2 724 1023 0.56 0.933 0.8 0.7 776 1078 0.56 0.933 0.8 1.1 816 1033 0.56 0.933 0.8 表 5 INCONEL 718合金热性能参数
Table 5. Thermal Performance Parameters of INCONEL 718 Alloy
T/℃ 热导率/
[W·(m·℃)−1]比热容/
[J·(kg·℃)−1]线膨胀
系数/10−6℃−1熔化温度/
℃20 13.4 11.8 1260~1320 300 17.8 481.4 13.5 1260~1320 -
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