Fracture toughness evaluation of a nuclear graphite with non-linear elastic properties by 3D imaging and inverse finite element analysis
Fracture toughness evaluation of a nuclear graphite with non-linear elastic properties by 3D imaging and inverse finite element analysis
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DOI：
10.1016/j.engfracmech.2023.109719
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发表时间：
2023-11
影响因子：
5.4
通讯作者：
Hongniao Chen;Jie Shen;Daniel Scotson;X. Jin;Houzheng Wu;T. Marrow
中科院分区：
文献类型：
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作者：
Hongniao Chen;Jie Shen;Daniel Scotson;X. Jin;Houzheng Wu;T. Marrow
由于辐照石墨的有限可用性限制了试样的数量和尺寸，因此需要进行有效的小试样试验来获得断裂韧性和弹性性能。在未辐照条件下具有非线性弹性性能的细晶石墨（SNG742）的双解理钻孔压缩（DCDC）试样几何形状的裂纹扩展试验中，同时评估了这两种性能。利用实验室原位x射线计算机层析成像的数字体积相关获得三维位移场，并采用小波方差法客观确定三维裂纹几何形状（裂纹尖端位置、裂纹张开位移和角度）。采用有限元模型更新（FEMU）方法对应变场进行反分析，确定了杨氏模量的拉伸软化。以导出的非线性弹性特性和实测位移为边界条件，在有限元模型中采用轮廓积分法计算准静态扩展裂纹的应变能释放率。临界应变能释放率随裂纹长度（118±14 J m−2）不变，相当于断裂韧性为1.13±0.07 MPa m1/2。
Effective small specimen tests are needed to obtain fracture toughness and elastic properties as the limited availability of irradiated graphite restricts the quantity and dimensions of test specimens. Both properties have evaluated simultaneously in a crack propagation test with the double cleavage drilled compression (DCDC) specimen geometry of a fine-grained graphite (SNG742) that has non-linear elastic properties in the unirradiated condition. Three-dimensional displacement fields were obtained by digital volume correlation of in situ laboratory X-ray computed tomographs, and the 3D crack geometry (crack tip position, crack opening displacements and angle) was determined objectively by a wavelet variance method. The tensile softening of the Young modulus was determined by inverse analysis of the strain field using the finite element model updating (FEMU) method. The strain energy release rate of the quasi-static propagating crack was calculated using the contour integral method in a finite element model with the derived non-linear elastic properties and the measured displacements as boundary conditions. The critical strain energy release rate was constant with crack length (118 ± 14 J m−2) and equivalent to a fracture toughness of 1.13 ± 0.07 MPa m1/2.