Investigation of pressure gradient effect on stress intensity factor variations in autofrettaged cracked thick-walled tubes using two dimensional weight function method

The autofrettaged thick-walled tube containing semi-elliptical crack is investigated. To study the variation of stress intensity factor on crack front، at first، two dimensional weight function is extracted. Stress intensity factor of all points on crack front can be calculate using proposed weight function، also، the complicated loading on crack faces including the loads due to axial gradient pressure in short cylinder and open-end tubes can be considered. Results show that، opposite of the cylinder subjected to uniform pressure، in pipes under gradient pressure، the maximum stress intensity factor are not necessarily on deepest point and surface points. The maximum stress intensity factor occurs on non-surface points in autofrettaged tubes. The results obtained from two dimensional weight function method have a good accuracy with the results obtained from finite element method. Prediction of fatigue crack configuration using two dimensional weight function can be more accurate than those obtained from one dimensional weight function.