The cohesive zone length is the sum of the cohesive element length at the failure edge and the lengths of the other cohesive elements connected to it. The cohesive zone length determines the maximum size of the mesh. Therefore, the accurate estimation of cohesive zone length and reasonable mesh division are important factors affecting calculation accuracy.

Based on several J-integral assumptions and existing research results, a modified function on length thickness ratio value is added to the original formula. The modified formula is then applied to an ice mechanics model. Based on the finite element method, a model of a double cantilever beam is established to verify the accuracy of the formula through comparison with the experimental results.

The results show that there must be at least four cohesive elements in a cohesive zone length to describe the fracture process accurately. This conclusion is also applied to the numerical simulation of a three-point bending experiment. The error of the limit load is 2.9%, and that of the fracture point is within a reasonable range.

It is concluded that the modified cohesive zone length formula is more suitable for ice materials.