A comparative study of non-linear fracture mechanics and linear elastic fracture mechanics for through wall cracks in cylinders

Background

The R6 method enables non-linear fracture mechanics analyses (NLFM) with the use of linear elastic fracture mechanics (LEFM). However for through wall cracks in cylinders, when running NLFM simulations, it has been noted that the position of the maximum J-integral along the crack front is dependent on the load level. This is not the case for LEFM. Hence, this is not considered when calculating the failure assessment diagram (FAD) with LEFM and adjusting it to non-linear fracture mechanics with the R6-method.

Goal

The goal with the master thesis is to determine if using the R6 method in the case described above is conservative or non-conservative. Furthermore recommendations are to be given how to correctly evaluate the results obtained from the R6 method for through wall cracks in cylinders to be certain of a correct conclusion of the actual safety margins. 

Assignment description

To achieve the goal of the master thesis a comparison of the non-linear fracture mechanic solution with the solution obtained via the R6-method is to be conducted. This will be done through FE-modeling and with the use of the R6 method implemented in the software ISAAC.

Education level: Masters degree

Estimated time: 20 weeks

Start date: According to agreement however not before spring 2019

Location:  Stockholm

Contact person: Tobias Bolinder, tobias.bolinder@kiwa.com

Application: is sent to tobias.bolinder@kiwa.com with attached grades and CV.