Investigation Of Ranger I Collaspe Metallurgical And Fracture Analysis

Abstract

The May 10, 1979, collapse of Ranger I, south of Galveston, Texas, occurred as a result of initiation and growth of a fatigue crack in the aft leg/ stiffener fillet weld runout. The 23 inch fatigue crack apparently developed and grew over the structure's lifetime.After the fatigue crack became critical and complete leg separation occurred, the leg moved laterally and dropped to the mat surface. The leg apparently remained in this general position for a period of time while settling into an attitude approximately 9· to II· off vertical. Applied loading became critical and the aft leg collapsed at the 44 foot level. This in turn allowed the aft end of the upper hull to fall. Hull side failure of the aft leg together with bending and separation of the forward legs followed.