Crack heating and retardation in a cylindrical shell wall by external pressure of various profiles

Potentiality of retarding the growth and healing of diverse types of cracks in cylindrical shells by applying a stressed bandage or an armor, compressing the shell from outside, was studied. Numerical calculation of mechanical strains in a cylindrical shell for different profiles of external pressure and uniform internal pressure was made. Analysis of the results obtained suggests the following. Radial stresses are always compressive stresses at non-zero internal pressure. Hence, as a rule, the growth of the cracks perpendicular to the radius and parallel to the shell surface is retarded. Axial stresses are tensile stresses. The axial stresses become compression stresses, if average pressure of the bandage on the cylindrical shell exceeds the internal one. Arrest of a longitudinal crack growth necessitates the external pressure on the bandage side to be in excess of the internal one, while the bandage length shall be by far longer than the crack size. In this case, compression annular stresses are applied to the longitudinal crack walls