Elastic-plastic collapse of non-uniform cylindrical shells subJected to uniform external pressure

摘要

The obJective of this paper is to derive analytical solutions for the elastic buckling and plastic collapse pressures of a cylindrical shell with reduced thickness over part of its circum- ference. The section of reduced thickness is used to represent a corroded region in a pipe. The proposed solutions are extensions of Timoshenko' s solutions for the elastic-plastic collapse of a linear elastic, perfectly plastic cylindrical shell subjected to uniform external pressure. A modihed interaction formula for the fully plastic membrane forces and bending moments in the non-uniform cylinder bas been proposed for plastic collapse. A parametric study shows that the elastic buckling pressure decreases smoothly witb corrosion angle when the corrosion depth is less than 0.5t. When the corrosion depth is greater than 0.51, the elastic buckling strength first decreases very rapidly with corrosion angle. Furthermore, the elastic buckling pressure decreases uniformly with corrosion depth when the corrosion angles are greater than 30 deg, while the elastic buckling strength decreases more rapidly at higher corrosion depths when corrosion angles are less than 30 deg. Another parametric study on a steel pipe shows that the initial and fully plastic yield pressures both decrease monotonically with corrosion depth for a given corrosion angle and imperfection.