Abstract: In order to study the failure mode of three-point bending beams under load, the failure process of three-point bending beams
with preset cracks at different locations and heights were simulated with particle flow code PFC2D. The simulation results show that the
length and location of prefabricated cracks affect the damage of beams together. When the location of prefabricated cracks is far from
the loading point, the height of prefabricated cracks is the main factor affecting the damage of beams. When the height of cracks
exceeds 70 mm, the failure mode of specimens changes. When the height of prefabricated cracks is fixed, the location of prefabricated
cracks is the main factor affecting the failure of specimens. When the distance from the support point exceeds 100 mm, the failure
mode of the specimens changes, and the failure process of the specimens are accompanied by the accumulation and release of energy.
Compared with the finite element method and the finite difference method, the discrete element method can better simulate the process
of material crack generation and development.

Key words: three-point bending beam, bias cracks, particle flow simulation, failure process