NASA Contractor Report 164058 APPLICATION OF THE LINE - SPRING MODEL TO A CYLINDRICAL SHELL CONTAINING A CIRCUMFERENTIAL OR AXIAL PART - THROUGH CRACK

In this paper the line-spring model developed by Rice and Levy is used to obtain an approximate solution for a cylindrical shell containing a part-through surface crack. It is assumed that the shell contains a circumferential or axial semi-elliptic internal or external surface crack and is subjected to a uniform membrane loading or a uniform bending moment away from the crack region. To formulate the shell problem, a Reissner type theory is used in order to account for the effects of the transverse shear deformations. The stress intensity factor at the deepest penetration point of the crack is tabulated for bending and membrane loading by varying three dimensionless length parameters of the problem formed from the shell radius, the shell thickness, the crack length, and the crack depth. The upper bounds of the stress intensity factors are provided by the results of the elasticity solution obtained from the axisymmetric crack problem for the circumferential crack, and that found from the plane strain problem for a circular ring having a radial crack for the axial crack. Qualitatively the line-spring model gives the expected results in comparison with the elasticity solutions. The results also compare well with the existing finite element solution of the pressurized cylinder containing an internal semi-elliptic surface crack.