Spatial variability in the coefficient of thermal expansion induces pre-service stresses in computer models of virgin Gilsocarbon bricks
Spatial variability in the coefficient of thermal expansion induces pre-service stresses in computer models of virgin Gilsocarbon bricks
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DOI：
10.1016/j.jnucmat.2015.05.058
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发表时间：
2015-10
影响因子：
3.1
通讯作者：
J. D. Arregui-Mena;L. Margetts;D. V. Griffiths;Louise Lever;G. Hall;P. Mummery
中科院分区：
文献类型：
--
作者：
J. D. Arregui-Mena;L. Margetts;D. V. Griffiths;Louise Lever;G. Hall;P. Mummery
在这篇论文中，作者验证了材料性能的微小空间差异可能导致原始石墨砖在服役前产生显著应力的假设。为此，他们定制了ParaFEM，这是一个开源的并行有限元程序包，增加了对使用蒙特卡罗模拟方法进行随机热机械分析的支持。对于先进的气冷堆砖，研究了三种加热情况：均匀的温度变化，均匀的温度梯度施加在砖的厚度上，以及运行中反应堆的模拟温度分布。比较了平均值和随机性的结果。这些结果表明，对于所进行的概念验证分析，当引入材料特性的空间变异性时，服役前的von Mose应力大约高出20倍。本文论证了温度梯度加上材料的不相容可能在核石墨反应堆砖的应力产生中起重要作用。热膨胀系数(CTE)和杨氏模数的微小空间变化会导致砖中存在可以自由膨胀的热应力。
In this paper, the authors test the hypothesis that tiny spatial variations in material properties may lead to significant pre-service stresses in virgin graphite bricks. To do this, they have customised ParaFEM, an open source parallel finite element package, adding support for stochastic thermo-mechanical analysis using the Monte Carlo Simulation method. For an Advanced Gas-cooled Reactor brick, three heating cases have been examined: a uniform temperature change; a uniform temperature gradient applied through the thickness of the brick and a simulated temperature profile from an operating reactor. Results are compared for mean and stochastic properties. These show that, for the proof-of-concept analyses carried out, the pre-service von Mises stress is around twenty times higher when spatial variability of material properties is introduced. The paper demonstrates that thermal gradients coupled with material incompatibilities may be important in the generation of stress in nuclear graphite reactor bricks. Tiny spatial variations in coefficient of thermal expansion (CTE) and Young's modulus can lead to the presence of thermal stresses in bricks that are free to expand.