External Pressure

The problem of tube collapse by external pressure has been investi-gated experimentally. A graphical solution developed t o simplify inelastic collapse design problems was shown t o agree with t h e t e s t results. The von Karman reduced modulus was used i n the graphical solution t o correct f o r t h e s t r e s s redistribution caused by yielding. The effects of the geometric imperfections of ovality and wall-thickness variations on collapse pressure were shown t o be related t o t h e stress-s t r a i n behavior of t h e material. The concept of a " c r i t i c a l time" was discussed i n regard t o creep-buckling phenomenon.