In situ measurement of the strains within a mechanically loaded polygranular graphite
In situ measurement of the strains within a mechanically loaded polygranular graphite
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DOI：
10.1016/j.carbon.2015.09.058
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发表时间：
2016
期刊：
影响因子：
10.9
通讯作者：
T. Marrow;Dong Liu;S. Barhli;L. S. Mora;Yelena Vertyagina;D. Collins;C. Reinhard;S. Kabra
中科院分区：
文献类型：
--
作者：
T. Marrow;Dong Liu;S. Barhli;L. S. Mora;Yelena Vertyagina;D. Collins;C. Reinhard;S. Kabra
采用中子衍射、同步x射线衍射和成像技术，原位研究了多颗粒核级近各向同性石墨（IM1-24）在拉伸和弯曲载荷下的力学响应。x射线照片的数字图像相关和层析成像的数字体积相关允许测量体弹性模量和检查微观结构中变形的非均匀性。中子和x射线的研究都表明，拉伸应变的应用降低了体弹性模量。在施加拉伸应变的情况下，观察到一个永久的集合。用衍射法测定了石墨晶体内部的弹性应变；互相关分析方法在测量基面分离距离变化时具有更快的速度、鲁棒性和更高的精度。在压缩条件下，石墨晶体的弹性应变与外加应变呈线性关系。在紧张状态下，这种关系是非线性的。讨论了石墨微观结构中弹性应变和非弹性应变的分布。结果表明，当施加拉伸应变时，石墨中的残余弹性应变通过微裂纹得到松弛。
Neutron diffraction and synchrotron X-ray diffraction and imaging have been applied to study, in situ, the mechanical response to tensile and bending loading of polygranular Gilsocarbon nuclear grade near-isotropic graphite (grade IM1-24). Digital image correlation of X-ray radiographs and digital volume correlation of tomographs allow measurement of bulk elastic moduli and examination of the heterogeneity of deformation in the microstructure. Both the neutron and X-ray studies show the application of tensile strain reduces the bulk elastic modulus. A permanent set is observed to develop with applied tensile strain. The elastic strains within the graphite crystals were measured by diffraction; a cross-correlation analysis method has been applied for greater speed, robustness and improved precision in the measurement of the change in basal plane separation distance. In compression, a linear relation is observed between the elastic strains in the graphite crystals and the applied strain. In tension, this relationship is non-linear. The results are discussed with respect to the distribution of elastic and inelastic strain within the graphite microstructure. It is deduced that the significant residual elastic strains in the as-manufactured graphite are relaxed by microcracking as tensile strain is applied.