Investigation of the size-dependent crushing behavior of Li4SiO4 pebbles via discrete element method

Li4SiO4 pebbles are commonly employed as breeder materials in solid breeder blankets. As a typical brittle material, the Li4SiO4 pebble sizes significantly affect their crushing behavior. In this study, the size-dependent crushing behavior of pebbles is investigated via discrete element method. Based on the Weibull theory, the probabilistic crushing strength of Li4SiO4 pebbles is analyzed. The numerical results demonstrate that both the characteristic crushing strength and Weibull modulus display a negative linear relationship with Li4SiO4 pebble size in a double-logarithmic plot. Furthermore, by considering both the axial force-displacement responses and fracture process of pebbles, three typical failure patterns of Li4SiO4 pebbles can be identified, namely, splitting failure (Pattern-I), progressive fracturing failure (Pattern-II) and explosive failure (Pattern-III). As the pebble size decreases, the failure pattern gradually shifts from Pattern-I to Pattern-II and to Pattern-III. Additionally, the fragment size distributions of crushed Li4SiO4 pebbles are analyzed based on the fractal theory. It is observed that the fragment size distributions of Li4SiO4 pebbles with varying sizes exhibit favorable fractal features. Smaller Li4SiO4 pebbles exhibit a more significant fragmentation, as evidenced by the increasing fractal dimension of the fragment size distribution with the decreasing pebble size. This work may provide valuable support for further investigations into the mechanical performance of a Li4SiO4 breeder blanket using DEM simulations.