An analytical approach to the analysis of inhomogeneous pipes under external pressure

Pipes for deep-water applications possess a diameter-to-thickness ratio in a region where failure is dominated by both instability and plastic collapse. this implies that prior to failure the compressive yield strength of the material must be exceeded,followed by ovalisation and further local yielding. this paper presents an investigation into the mechanics of this specific problem and develops an analytical approach that accounts for the effects of geometrical and material data on the collapse pressure of inhomogeneous rings under external hydrostatic pressure. the analytical expressions have been correlated to numerical and experimental test data,proving their accuracy. © 2012 massimiliano fraldi and federico guarracino.