Abstract：When a disc specimen was under a radial load, the crack point along the disc thickness direction was not shown a simple linear form, thusly it is necessary to analyze the three dimensional configuration of a crack.With three-dimension fracture analysis software, FRANC3D, the stress intensity factor of disc specimens with different shapes of three-dimensional arc-shaped cracks were calculated.The results showed that the stress intensity factor on the crack edge along the disc thickness varied with the circular angle γ of the arccrack and relevant no-dimensional crack length.The three-dimensional stress intensity factor distribution rules were obtained, and the first fracture point of the different forms of a three-dimensional crack were analyzed according to the mode I fracture criterion.This is helpful to further understand the crack fracture and expansion rules.

Keyword：disc specimen;three-dimensions stress intensity factor;arc-shaped crack;fracture analysis code in 3 dimensions;