多层各向异性包壳力学模型开发与应用

Development and Application of a Mechanical Model for Multilayer Anisotropic Cladding

由高致密度纯SiC和SiC纤维/基体复合材料(SiCf/SiC)组成的多层SiC复合包壳是当前事故容错燃料(ATF)包壳的热门选型,当前应用的典型燃料性能分析程序缺乏对于SiCf/SiC材料各向异性力学行为的建模能力,为提高燃料性能分析中复合SiC包壳力学计算的准确性,本文开发了一套适用于多层各向异性材料的力学模型,并将其集成到燃料性能分析程序FRAPCON4.0中,采用多层SiC包壳热力耦合算例对模型正确性进行了验证。实现了对具有正交各向异性力学特性和多轴类塑性行为的SiC复合包壳的力学计算功能,分析了双层SiC包壳燃料元件堆内稳态运行工况的性能。本研究建立的力学模型适用于任意多层圆柱结构燃料元件,并具备正交各向异性力学参数及行为的分析能力,可应用于多种新型燃料元件分析。

The multilayer SiC composites cladding composed of monolithic SiC and SiC fiber/matrix composite(SiCf/SiC)is a popular choice for accident-tolerant fuel cladding.However,typical fuel performance analysis codes currently lack the modeling capability for the anisotropic mechanical behavior of SiCf/SiC materials.In order to enhance the precision of mechanical calculations for composite SiC cladding in fuel performance analysis,a mechanical model was developed for multilayer anisotropic materials and integrated into the fuel performance analysis code FRAPCON4.0.Validation of the model's accuracy was conducted using a multilayer SiC cladding thermal-mechanical coupling case.The mechanical calculation capability for SiC composite cladding with orthotropic mechanical properties and multiaxial pseudoplastic behavior was achieved,and the performance of duplex-layer SiC cladding fuel elements under normal operation condition was analyzed.The developed mechanical model in this study is adaptable to arbitrary multilayer cylindrical structure fuel elements and has the capability to analyze orthotropic mechanical parameters and behaviors,rendering it applicable to various types of novel fuel element analyses.