Study On Fragmentation Characteristics About Particle Of Pebble Bed Based On Finite Element Method

Tritium is usually proliferated and extracted in the cladding in fusion reactors.As the main carrier of tritium self-sustaining function,the dynamic and static characteristics of the internal filler are very important to the fusion reactor.The stress of the breeder particles is very complex due to the special service environment of the coated pellet bed,and the breakage of the particles is difficult to avoid.Therefore,it is necessary to analyze the crushing characteristics and mechanical properties of the pellet bed breeder material in order to analyze the influence of crushing on the structure of the pellet bed.Based on the above purposes,the following studies are carried out in this paper:Firstly,based on the application of fractal theory in the characterization of particle breakage,the impact breakage experiment of glass ball was designed,the fractal distribution of particle breakage behavior was studied,and the relationship between the degree of breakage and impact energy was analyzed.The experimental results show that:Brittle particles will not be broken indefinitely with the increase of impact energy,but there is a breaking limit,which can be characterized by the limit fractal dimension.The above study also verifies the validity of fractal theory applied to study particle breakage behavior under impact load.Then,through the single particle quasi-static compression experiment of two kinds of pellet bed particle materials,lithium silicate(Li4SiO4)and lithium titanate(Li2TiO3),the mechanical properties and crushing characteristics under uniaxial stress are deeply explored,and the peak compressive force and displacement load during crushing of lithium silicate and lithium titanate particles are obtained.By applying Weibull distribution theory,the Weibull modulus was calculated,and the compressive crushing strength and tensile strength under 37%survival rate of particles were obtained,and the crushing limit parameters of particles were determined.Finally,based on the finite element model of two pellet bed granular materials,lithium silicate and lithium titanate,the single particle compression crushing numerical simulation was carried out by Workbench LS-DYNA explicit dynamics module,and the particle compression deformation mechanism was explored.The stress value curve of the material under load was obtained,and the stress distribution cloud diagram was derived.The correctness and rationality of the numerical simulation experiment are verified by comparing the data with the corresponding experimental results.To sum up,based on the numerical simulation method,combining with the experiment of lithium silicate and lithium titanate two ball bed particle breakage characteristics and mechanical properties are analyzed,the related model and parameters for two kinds of material research provides the experimental and data support,for fusion cladding ceramic ball bed granular material mechanics performance of the research provides the theoretical and experimental basis,It can also provide reference for experimental and simulation study of pellet crushing.Figure [50] Table [10] Reference [73]...