A Comparison between the 3D and the Kirchhoff-Love Solutions for Cylinders under Creep-Damage Conditions

The 3D theory of creep deformation and creep damage growth in a cylindrical body of revolution is considered. Constitutive equations describing the creep deformation and unilateral creep damage in initially isotropic materials with characteristics dependent on the kind of the stress state are discussed. The numerical approach to obtain the 3D solution for a cylinder under creep-damage conditions is developed. The numerical results generated by the proposed 3D theory are compared with the analogous results based on the Kirchhoff-Love model. Thin and moderately thick cylindrical shells of revolution made from the material with the creep and creep damage characteristics dependent on the kind of the stress state are considered in this comparative analysis. The influence of tension–compression asymmetry on the stress–strain state and damage evolution with time in thin and moderately thick cylindrical shells is discussed. If it is assumed that the properties of the shell material do not depend on the kind of the stress state, this could lead to an overprediction of the creep damage growth and a significant underestimation of the failure initiation time

Transversal Shear Effect in Moderately Thick Shells from Materials with Characteristics Dependent on the Kind of Stress State under Creep-Damage Conditions: Theoretical Framework

The refined theory of creep deformation and creep damage in moderately thick shells of revolution which accounts for transversal shears and additionally for nonlinear distribution across its thickness of the components of the strain tensor as well as of the angles of rotation of the triad of vectors defined the position of the arbitrary point of a shell is discussed. A constitutive model for describing the creep deformation and directional nature of damage under creep conditions in initially isotropic materials with characteristics dependent on the kind of the stress state has been used. The governing equations of the moderately thick shell theory under discussion are introduced, and the initial/boundary-value problem in the frame of the physical nonlinearity and geometrical linearity has been formulated. The numerical tool developed for analysis of creep deformation and creep damage in moderately thick shells of revolution using the proposed theory is discussed